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eHam Forums => Boat Anchors => Topic started by: KD0ILM on January 31, 2015, 04:06:54 PM



Title: How hot does a Boat Anchor get?
Post by: KD0ILM on January 31, 2015, 04:06:54 PM
There are a lot of small LCD digital temperature gauges with probes on them for sale. For my personal interest I want to measure the temperatures inside my Heathkit tube amplifiers and radios (101,102,200,220, 301,401) and how they vary with use. Does anyone know generally speaking what upper limit I should look for in a device? I realize that up to tube melting temperature is one answer but I am looking for the temperature of a radio that is in normal use. I am also guessing the most useful information might come from the finals cage of the transmitters.
Opinions please
Kevin
KD0ILM


Title: RE: How hot does a Boat Anchor get?
Post by: AA4HA on January 31, 2015, 07:20:26 PM
Generally most boat-anchors I have owned have not pushed much more than 120 F as an ambient internal temperature. There are always exceptions to that and as you can imagine, a tube amplifier can run quite a bit warmer. Not to the point where you are going to fry the fingerprints off of your fingers but right up the upper limits of comfort.

Surprisingly it ends up being some smaller devices that run hotter, things like a CV-591 (SSB adapter) that is chock-full of tubes in a very small package.

They try to limit temperatures because capacitors do not like it.


Title: RE: How hot does a Boat Anchor get?
Post by: W4OP on January 31, 2015, 07:40:02 PM
I find a good deal of difference when running my BA's of the AC socket (something I no longer do) as opposed to running through a bucking transformer to bring the voltage to 110VAC- where it was "back in the day".

Dale W4OP


Title: RE: How hot does a Boat Anchor get?
Post by: G3RZP on February 01, 2015, 08:18:21 AM
Depends on the rig. I have an Eddystone 888A ham bands rx: 8 tubes in the signal path, plus one in the crystal calibrator, a 5Z4G rectifier and a VR150 stabiliser. About 16 inches wide , 8 inches high and about 9 deep. It gets too hot to comfortably keep your hands on the pretty well ventilated case, so it must be around at least 55 degrees C (131 deg F) inside.

Generally, as you might expect, the greater the number of tubes and the smaller the box, the hotter it gets. Maritime radios for compulsory fitting had to meet full spec from -15degC (5 deg F) to + 55 degC  ambient. I'm not sure how the crew were supposed to function at the upper limit, though!

My Drake TR3 got warm, but not probably over a case temperature of 40 or so degrees in a 22 deg C ambient.


Title: RE: How hot does a Boat Anchor get?
Post by: KD8IIC on February 02, 2015, 08:33:52 AM
 I think I can warm a sandwich or make toast on top of my Johnson TR Switch. The old heads report that it is normal for the device.  73


Title: RE: How hot does a Boat Anchor get?
Post by: WB4SPT on February 02, 2015, 09:23:09 AM
I want to measure the temperatures inside my Heathkit tube amplifiers and radios (101,102,200,220, 301,401) and how they vary with use. I am also guessing the most useful information might come from the finals cage of the transmitters.
Opinions please
Kevin
KD0ILM


My opinion is to encase the probe cable in teflon tubing, including the end.  :o


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 02, 2015, 09:43:24 AM
What is your thinking about the teflon tubing?


Title: RE: How hot does a Boat Anchor get?
Post by: G3RZP on February 02, 2015, 09:59:54 AM
Stops you touching some high voltage point by mistake? Trouble is, it will act as a heat insulator....


Title: RE: How hot does a Boat Anchor get?
Post by: KD0REQ on February 02, 2015, 10:47:33 AM
the old problems never go away.  heat kills components.  they didn't used to publish derating curves back in the tube days, but electrolytics were commonly rated to 140 Fahrenheit.  at that temp, the wax flowed near hot spots by tube sockets and the caps would short.  rubber wire insulation cracked to allow arcing.  resistors would slowly go into runaway and bake to high values.  the old grey engineers at the radio station said if it's comfortably warm, it's OK.  if it's raw hot water warm, you have a problem, send the talent into another studio and take this one down.


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 02, 2015, 10:56:33 AM
I have found some in expensive , quiet portable, controllable (simple switch on the fan) computer fans. I want to get some baseline figures. If I think any of them are running too hot for me I want to experiment by just putting the fans on the top of the cases (HK thoughtfully provides cases full of holes), and blow air over the tubes on a parallel axis. The fans are really quiet and I don't want to hack up the radios. I am particularly  interested in running an SB-301 and SB-401 (transmitter and receiver) on top of each other which may present heat problems.


Title: RE: How hot does a Boat Anchor get?
Post by: WA4NJY on February 02, 2015, 12:43:06 PM

 Does it really matter what the top cabinet temperature  is?  If heat is flowing upward out of the cabinet, should not cooler air be drawn up from above or below the chassis by this convection?

Any fans could be placed on a ventilated cabinet top to assist the upward flow of hot air.  Or am I the hot air?

Ed


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 02, 2015, 12:50:48 PM
This is why I am doing the experiment.  :)
I don't have a clue!!


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 02, 2015, 12:50:56 PM
Heat is not good for filter caps, nor the organic insulation used in transformers. If I have a radio that runs hot, I'll take steps to reduce the AC voltage to 110 or 115 VAC.  That often makes a big difference.

Pete


Title: RE: How hot does a Boat Anchor get?
Post by: WB4SPT on February 02, 2015, 01:02:26 PM
Stops you touching some high voltage point by mistake? Trouble is, it will act as a heat insulator....

OK, 2nd try.  I've solved that plus the electricity issue. 

http://www.omega.com/pptst/TL-10.html


Title: RE: How hot does a Boat Anchor get?
Post by: HFCRUSR on February 02, 2015, 01:06:54 PM
For what it's worth, I run a 12v fan, airflow-out at the power supply side of my 20-tube boatanchor. This way, it draws in fresh air from the audio side and pulls the heat out the rear of the hot side. Even the transformer is cooler. Without that fan it gets hot enough that you cannot touch the hood on the power side. Plus I run it at 110v off a variac. Even though the hood is perforated, IMHO it does not dissipate enough heat.
Small drawback is having to vac dust from the audio side and rear of the variable cap house.


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 02, 2015, 01:32:18 PM
Does it have the amount of holes that a Heathkit does in the cover? Also considering gluing 4 very eak magnets on the corner of the fan so I can move it around but worry that I will only cause myself trouble with the "magnetism" on the case.


Title: RE: How hot does a Boat Anchor get?
Post by: HFCRUSR on February 02, 2015, 01:52:01 PM
My whole hood is meshed, then there are a dozen air slots in back, and a bunch on each side. But if you aren't somehow moving air outside the shell, the air inside will stay and heat up-hence the fan. You should just place a fan with the airflow pointing away from the radio, near any airslots close to the heat source. This will draw the heat out that way before it has the chance to build up in there. With the amount of air flowing, it should be effective.
My fan isn't attached at all-just sits on its own.
Plus, what I did you can also do to check airflow; just fire up a cigarette, or incense stick or anything that will emit a stream of smoke, then move it around the radio inlets while the fan runs, to get an idea how and into where air is flowing. You can do this to gain the best fan position.


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 02, 2015, 02:33:25 PM
All good ideas


Title: RE: How hot does a Boat Anchor get?
Post by: HFCRUSR on February 02, 2015, 02:42:02 PM
All good ideas
thx-except maybe the cigarette one-you don't want tar juice inside the radio :P
by the way, here is a pic of the 12v fan I use-I forgot to put it into my 1st post. It plugs right into the switched outlet in the rear of my radio so it goes on with it :)
(http://i739.photobucket.com/albums/xx34/ridgerocker2001/IMG_0577_zps5856c5cb.jpg) (http://s739.photobucket.com/user/ridgerocker2001/media/IMG_0577_zps5856c5cb.jpg.html)


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 02, 2015, 02:49:01 PM
I rebuilt HK from a smoking environment one time and was stunned at how much tar could accumulate inside a radio with no fan.


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 03, 2015, 05:46:19 AM
 Perforated metal covers actually flow a lot less air that many people realize . The heated air carried by convection rises but when it strikes the inter-hole webbing it is stopped . This reversal sets up eddy currents that oppose the flow thru the holes . 

  This is pretty easy to see by placing a small smoking source inside a perf cabinet .
A few tears ago I fabricated a cover for a Stromberg Carlso PA amp that I had converted into a modulator .

  The cabinet was designed to make use of the internal convection current to direct airflow thru the cabinet across the areas where cooling was most benficial .  The cabinet had generous horizontal slots placed low , across the front of the power tubes to draw the bulk of the coolest intake air across the power tubes .

  The rear of the cabinet had high mounted slots that wrapped around the top corner from high on the backside of the cabinet . The exhaust vent area was 50% larger than the intake to allow for the greater volume of heated exhaust air .

   The system worked very well . I could hold a smoking rope near the air intake while the amp was cold and the smoke would rise straight away . As the amp heated , the smoke was drawn very strongly across the power tubes , across the rear and out of the top vent , just as intended .

  The result was a  15 to 20 degree F drop in temps within the cabinet .

    Directing the natural convection flow can help promote cooling that may rival and in some cases achieve better results than forced air fan cooling .


Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 03, 2015, 05:05:56 PM
125/110 volts is about 1/4 less quiescent heat in steady load equipment, but only a small change in transmit heat in transmitters and amplifiers. A little gentle tickle of forced air in the right direction in a convection cooled device is a lot more dramatic.


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 04, 2015, 08:41:43 AM
 Yes indeed , properly done forced ventilation is very effective . Most attempts that I have seen are far from well thought out .  Baffling and flow direction are key elements . Setting a muffin fan atop a perf-metal  enclosure often is best only  at adding a bit of background noise.

   The passive methods can be very effective and quietly efficient .

Pics here:
https://microphoneprojects.shutterfly.com/pictures/11 (https://microphoneprojects.shutterfly.com/pictures/11)


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 04, 2015, 09:10:54 AM
You make a very good point. These radios have lasted for decades with the factory designed cooling. Of course I can't leave well enough alone and want to use a probe just to see what is what and what if any difference a fan makes. I have been given some thoughtful advice some given with quite a bit of humor. Thanks


Title: RE: How hot does a Boat Anchor get?
Post by: K8AXW on February 04, 2015, 09:38:27 AM
There are several things that will make boat anchors run hot.  The main thing to remember is, if it get too hot it will start smoking.  THEN you can surmise that it is running too hot and something is wrong.

Otherwise, plug 'n play!


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 04, 2015, 10:02:33 AM
There are several things that will make boat anchors run hot.  The main thing to remember is, if it get too hot it will start smoking.  THEN you can surmise that it is running too hot and something is wrong.

Otherwise, plug 'n play!

Or.....

    Make some simple changes to improve cooling and increase the time between smoke releases .  There are exceptions , certain areas such as VFOs where a constant temperature is desireable  .   Not necessarily a high temp however . Temperature control can be advantageous in most cases .


Title: RE: How hot does a Boat Anchor get?
Post by: HFCRUSR on February 04, 2015, 10:49:18 AM
There are several things that will make boat anchors run hot.  The main thing to remember is, if it get too hot it will start smoking.  THEN you can surmise that it is running too hot and something is wrong.

Otherwise, plug 'n play!
Then there's the old saying "heat kills" in radio world. If so, then why hand it the ammo, especially given the age and temperament of these older ones. Besides, at least with mine, ssb is far less drifty when it's cooler in there. Same with my r71a.


Title: RE: How hot does a Boat Anchor get?
Post by: K8AXW on February 04, 2015, 09:37:57 PM
If it's a "boat anchor" then it isn't dead.  Heat never killed it.  Sure, heat isn't good for a radio but this was the the way it was!

Cooling a boat anchor can cause drift and in some cases MORE than if it's left alone.  I have read many times when reading instructions on a piece of gear...."After 10 minutes, the frequency becomes stabilized" or something to that effect.

I can find other things to agonize over rather than the heat generated by a boat anchor.


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 05, 2015, 04:23:59 AM
If it's a "boat anchor" then it isn't dead.  Heat never killed it.  Sure, heat isn't good for a radio but this was the the way it was!

Cooling a boat anchor can cause drift and in some cases MORE than if it's left alone.  I have read many times when reading instructions on a piece of gear...."After 10 minutes, the frequency becomes stabilized" or something to that effect.

I can find other things to agonize over rather than the heat generated by a boat anchor.

  Obviously !  You seem to be agonizing quite  a bit indeed over people taking measures to preserve the gear they own .


Quote K8AXW : "If it's a "boat anchor" then it isn't dead.  Heat never killed it."

 A flawed assumption at best ;
 Many boat anchors that are indeed alive again today because they have had parts replaced that failed from heat related problems . Most electrical components carry a de-rating factor that increases in proprtion to operating temperature . Many boatanchors have suffered common component failures as a result of poor cooling considerations by the original designer .
   Frequency determining components were mentioned long ago as an area where temperature control is an issue .  A VFO can be very stable at a constant low temp and less so at a fluctuating high temperature .
  There are many areas in power equipment where enhanced cooling is beneficial .  A little thought and analysis beats the broad brush mentality . 

   


Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 05, 2015, 05:05:30 AM
I wouldn't be too critical of K8AXW's "flawed assumption".

I can't think of many boat anchor rigs I've had where cabinet internal heat has reduced life. Factually, heat can even extend life.

Most boat anchors component failures I see failed because of age. Electrolytic capacitors deform from non-use, resistors and capacitors open from moisture enhanced corrosion, tubes gas up from lack of running at operating temperatures.

There are cases of heat failures, to be sure. For example, carbon composition resistors commonly age down in value (go "shorted") when subjected to prolonged excessive heat. Electrolytics can develop leakage at elevated temperatures, and might dry out sooner.

Drift is often a function of temperature delta, not absolute temperature. Drift can be compensated out with proper components to the point where temperature delta has little meaning. Running something cooler with forced ventilation might actually prolong warm up time for stability.

All of the worry about heat, unless some component is actually going over safe limits, is generally a waste of time. We can blow all the air we want on the outside of a glass envelope tube, and the internal elements stay at about the same temperature. You can cool the glass, but that isn't generally a failure point. Tube wear is mostly caused by filament hours and internal thermal cycling, and the failures mostly by luck of the draw.

When I think about all the tube rigs I have, the parts that fail almost always have failed just because of time. I can go to a box of 40 year old electrolytics that have never been warm, and never run, and they are as likely or more likely to be bad as any other capacitor in a "hot" radio. The same is true grabbing new old stock carbon resistors, or new old stock capacitors, from boxes.

Cooling the cabinet is predictably good for one thing, it almost always makes the operator feel better about the radio.


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 05, 2015, 05:54:43 AM
   Manufacturers of electrical components typically de-rate components as operating temperatures are increased . They do this for many very good reasons .
   Insulation breakdown voltages drop as temeratures rise , resistors change more rapidly as temps increase . Transformer winding insulation on older transformers is degraded and it's life shortened by elevated temperatures .  Not an opinion , a recognized fact .

 Not in the least advocating hanging biscuit fans all over every piece of gear . However , getting back to my first posting there are some opportunities to improve cooling as well as component life with simple changes that promote better airflow to critical areas . Passive , convection current cooling can be very effective indeed .   https://microphoneprojects.shutterfly.com/pictures/11 (https://microphoneprojects.shutterfly.com/pictures/11)
  
 Glass envelope power tubes like the 3-500z anode seals fail when deprived of proper cooling .

  Yes , the statement "If it's a "boat anchor" then it isn't dead.  Heat never killed it."

As an absolute is indeed a flawed assumption .  I have replaced a lot of parts that would have functioned far longer and likely would not yet have failed at lower temperatures .   The manufacturers of components such as electrolytic capacitors realize this and readily admit it .
 


Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 05, 2015, 03:15:43 PM
Oddly, the dozens and dozens of radios I have in my possession do not have that problem.

I guess, like K8AXW, my experience is different than just lifting data out of context and making it a rule.


Title: RE: How hot does a Boat Anchor get?
Post by: KD0ILM on February 05, 2015, 04:40:27 PM
I would agree that that most if not all reputable Ham radios were built to operate in their natural conditions. Convective cooling works well where it was designed to do so, amps have all different kind of systems that work.

Heathkits are said to have carbon composition resistors that age (general up) and need replacing. This is true of all or most 30 or more year old carbon resistors. I remain surprised at how many of them are still good when checked with good equipment. When I tear into one I general don't find more than 30% of them beyond my replacement criteria. Most of them are specced at 10% and I stick with 5%. Most are within that spec. I am not going to be around to discover if the new carbon film resistors I am installing will last at least that long. All this with standard cooling.

My questions about what temperatures they generally run at was only to get a baseline so I could buy the correct temperature measuring equipment. The rest of it is just for fun. I am not trying to reinvent the wheel or improve something that may not need fixing. I am just looking for something to play with while listening to nets, working digital or calling CQ on a quiet band.

I am working at rebuilding an SB-301 and 401 receiver and transmitter and also want to see if I can get away with stacking them. I am short on space and it would not be my normal choice.


Title: RE: How hot does a Boat Anchor get?
Post by: K1DA on February 05, 2015, 06:36:44 PM
The audio amp in the 75S series runs hot enough to fry an egg, but the tubes last a long time.


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 06, 2015, 04:54:03 AM
Oddly, the dozens and dozens of radios I have in my possession do not have that problem.

I guess, like K8AXW, my experience is different than just lifting data out of context and making it a rule.

   What problem ?  
Who has lifted anything from context and made a rule ?  The strawman approach doesn't really cut it .
Again :
  Not in the least advocating hanging biscuit fans all over every piece of gear . However , getting back to my first posting there are some opportunities to improve cooling as well as component life with simple changes that promote better airflow to critical areas . Passive , convection current cooling can be very effective indeed .   https://microphoneprojects.shutterfly.com/pictures/11
 What rule ?


  The shotgun approach of drilling thousands of holes in an attempt to secure cooling is often less effective than placing intake and exhaust vents strategically to promote convection cooling .  It may be ok for bragging rights but to some it looks pretty lame .
 The typical "amateur" swiss cheesing can actually impede cooling .

    To state that certain components last longer when run at lower temperature is a fact . Read the data on electronic component testing . The life of many components is a direct inverse proportion to the operating temperature .

   Good design will place temerature sensitve components away from heat producing components when possible .

   So little time to put any real use to dozens and dozens of radios anyhow ....

The audio amp in the 75S series runs hot enough to fry an egg, but the tubes last a long time.

   The tube is not the real issue . Take an application where the hot running tube is mounted horizontally , place a couple of 85 degree C electrolytic cans directly above it and their life expectency will plummet . 
Reverse the situation , place the caps below the tube , add a reflective baffle and the average cap life will be extended significantly .

   Illinois Capacitor ratings for aluminum electrolytics run like this :  Take a  450 volt electrolytic with a life rating of 500 and a 85Deg C temp rating . Operating at85 deg ambient , the projected life is 563 hours . Drop the ambient temp to 70 degrees and the life extends to 1,591 hours , nearly tripled the life !

    


Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 06, 2015, 11:42:04 AM
The audio amp in the 75S series runs hot enough to fry an egg, but the tubes last a long time.

That's because the temperature inside the tube doesn't change as radically as temperature outside, and it is designed to run hot.

Look at MTBF on electrolytic caps.   Data is often extracted from context of a large process, and used to come up with a claim a temperature reduction of xx degrees will make the life go from Y hours to Z hours.

As amateurs, we don't operate out equipment in CCS service. Most components in amateur service relate more to shelf life and off-and-on cycles, or abuse, than operational life. Some things, like many Chinese tube types, only have hours of life no matter how they are operated. While most old quality tubes might have 5,000 or 10,000 hours of operation in conservative CCS operation, some tube types fail in 100 hours or less just by running the filament at 90% voltage without any emission current or thermal cycling.

To decide if a lower cabinet temperature would actually change anything, we would have to look at what failed and why it failed.

Nearly all of the old radios I have have capacitor failures just because of age. The equipment spends 90% or more of its life off, just sitting a shelf. Resistors age from moisture ingress, capacitor seals dry out, wax cracks, materials inside corrode; the list goes on and on.

I got a Globe Scout 65A down off the shelf in a dry storage building the other day, for example. It has one of the worse cabinets for ventilation, and component voltages are all over the place. It had original electrolytics, tubes, and most other parts. I've owned it for maybe 30 years, and that entire time it sat unused. (I have many amplifiers and radios like that, some dating back to the 1910's.)

I plugged it in, tuned it on, and it ran. The only issue making it unusable was the filter capacitor lost capacitance. This is an early or mid 1950's capacitor. I doubt reducing cabinet heat would make a 60 year old paste-electrolyte capacitor live longer in something that spends most of its life sitting cold.

The common issue people really have with old radios not working is the radios are old. If they had thermal issues noticeably shortening life, they would not be loaded with OEM parts. If heat on wires was an issue, the wires would have dried out years ago.

I can replace the electrolyics in that supply, and the Scout will be good for the shelf life of the new caps. If I put a 100 CFM fan on it, the parts inside will last around the shelf life of the parts even if I operated it as a main radio.

Now if it was at a BC station and ran 24/7, I'd worry about heat and component headroom. Many parts would not make it to expected shelf life.


Title: RE: How hot does a Boat Anchor get?
Post by: N3QE on February 06, 2015, 12:22:15 PM
In the wintertime in a cold shack, a HW-101 is "nicely and comfy warm" in the shack while operating, not much above body temperature.

If it's 90 degrees ambient in the summertime, the HW-101 cabinet can get almost too hot to comfortably touch (130F-140F). At the same time, any dark car outside in the sun is way hotter!!!


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 06, 2015, 01:57:31 PM
Many older boat anchors benefit from running at reduced input voltage. Dropping from 125 to 115 VAC often makes a substantial difference in boat anchor temperatures, esp. the power transformer cores, without resorting to external cooling devices.  Anyone who believes that the organic based insulation used in vintage transformers benefits from being running hot should invest in some bridges that I have for sale. Those radios were designed to be produced as cheaply as economically possible. After 50 or 60 years, parts will be deteriorating or failing. There are a lot of dead boatanchors with destroyed power transformers floating around. I'd rather keep mine running properly, for my use, and for the next guy down the road.

Pete


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 06, 2015, 03:38:15 PM
Many older boat anchors benefit from running at reduced input voltage. Dropping from 125 to 115 VAC often makes a substantial difference in boat anchor temperatures, esp. the power transformer cores, without resorting to external cooling devices.  Anyone who believes that the organic based insulation used in vintage transformers benefits from being running hot should invest in some bridges that I have for sale. Those radios were designed to be produced as cheaply as economically possible. After 50 or 60 years, parts will be deteriorating or failing. There are a lot of dead boatanchors with destroyed power transformers floating around. I'd rather keep mine running properly, for my use, and for the next guy down the road.

Pete

  Good points , all . In fact some of us do use our radios and there is certainly no harm done by taking measures to ease the temperature strains in some of the higher power stages . Anecdotes of radios that are seldom used have little bearing on the hard fact that elevated temperatures do indeed measurably shorten the working life of many components . 


Title: RE: How hot does a Boat Anchor get?
Post by: KK5DR on February 08, 2015, 08:19:09 AM
It's not important how hot the box gets. It's more important that individual tubes not get too hot. Temp specs have been published for each tube. Easy enough to find the data and measure the tubes.


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 08, 2015, 08:37:58 AM


I can replace the electrolyics in that supply, and the Scout will be good for the shelf life of the new caps. If I put a 100 CFM fan on it, the parts inside will last around the shelf life of the parts even if I operated it as a main radio.

Now if it was at a BC station and ran 24/7, I'd worry about heat and component headroom. Many parts would not make it to expected shelf life.

Electrolytic capacitor life is generally based on ripple current and temperature. The manufacturers' data sheets provide that data. A cap run at maximum ratings may have a rated life of only 1000 hours.  You can't make generic statements as fact based on anecdotal person experiences. Besides, many hams are shopping for cheap Chinese crap parts on eBay, instead of ordering from reliable US distributors.  I note that your website has a section devoted to undue transformer duress caused by the increased peak repetitive charging currents caused by replacement silicon rectifiers. Same goes for reducing the AC line voltages. The transformer runs cooler. That is something that can be measured, and shown.


Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 09, 2015, 03:45:53 AM


I can replace the electrolyics in that supply, and the Scout will be good for the shelf life of the new caps. If I put a 100 CFM fan on it, the parts inside will last around the shelf life of the parts even if I operated it as a main radio.

Now if it was at a BC station and ran 24/7, I'd worry about heat and component headroom. Many parts would not make it to expected shelf life.

Electrolytic capacitor life is generally based on ripple current and temperature. The manufacturers' data sheets provide that data. A cap run at maximum ratings may have a rated life of only 1000 hours.  You can't make generic statements as fact based on anecdotal person experiences. Besides, many hams are shopping for cheap Chinese crap parts on eBay, instead of ordering from reliable US distributors.  I note that your website has a section devoted to undue transformer duress caused by the increased peak repetitive charging currents caused by replacement silicon rectifiers. Same goes for reducing the AC line voltages. The transformer runs cooler. That is something that can be measured, and shown.

That is a worse generalization than anything.

1.) A transformer's expected life has little change unless it goes over some failure rating. It is not remotely close to a linear curve or straight line with temperature. If you get close to insulation thermal ratings, it is a problem. If the transformer is well away from limits, it doesn't matter how hot it is run.

2.) I see many people who think the little hour numbers on a capacitor's case directly mean something. There is a rather complex estimated life calculation that has to be used, and most capacitors (even at 75C) last many thousands of running hours. In amateur service, unless sometime very serious is wrong, shelf life and just the chance of getting a bad part generally become the dominate players.

It's difficult for me to put this in words, but there is a common tendency (that I can't quite understand) to lift a single fact from a bunch of complex data and extrapolate it into a universal law that has nothing to do with the original fact.

We get goofy stuff rules like "If you make the radio run cooler it will last longer" because somewhere there is a complex formula for MTBF that shows increased temperature decreases life.

I'm sure there is a name for the tendency to extracting a single truth from a complex behavior and making that single thing some sort of unlikely generalized rule.  I don't know what it is, but it sure happens a lot.

I see very few old radios that have heat-related component failures. The primary issues I see, and I have dozens of pieces of old junk, are related to age and storage humidity. If they were run at 50F or 150F internally up where the tubes heat things, they would be in same general shape.

Another case in point. There is a thread in this forum about resistors going bad. The normal carbon resistor aging from elevated temperature is a decrease in resistance. The normal carbon aging from humidity is an increase in resistance. Look at which of the two most people report in that thread. Since almost all increased resistance failures are related to humidity, I could make a silly argument if people ran the resistors warmer to keep them dry, they would still be good. The real issue is the age and humidity. The same is true with many other component failures in old rigs.

 



Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 09, 2015, 04:05:37 AM
I got a Globe Scout 65A down off the shelf in a dry storage building the other day, for example. It has one of the worse cabinets for ventilation, and component voltages are all over the place. It had original electrolytics, tubes, and most other parts. I've owned it for maybe 30 years, and that entire time it sat unused. (I have many amplifiers and radios like that, some dating back to the 1910's.)

Strawman argument. Tom, you continue to use anecdotal personal observations passed off as factual information to deflect the issues.

In the real world, none of those radios were designed to last more than several years, and at minimal cost to the manufacturer. We're not talking 1960's era HP test gear, but equipment that was aimed at a cheap consumer market. I can think of numerous examples of known issues in early boat anchor gear that are age related.  For one example, the power transformers used in the Hallicrafters HT-32 are known to develop shorts between the HV and rectifier filament windings.  Prudent restorers replace the tube rectifiers with diodes. Of course, there are quite a few HT-32 parts donors out there from owners who figured they could just plug them in, and run them.

A majority of the early Atwater Kent cathedral sets have very weak transformers. I've seen them fail days after a set was placed in use, after complete restorations. In some cases, the tar used to seal vintage transformers is acidic, shortening their usable service life. The same for the tar filled Bakelite block capacitors used in Philco sets... tar filled, and one that doesn't have major leakage issues is a rare find. Same for wax sealed paper caps. Heat may not harm tubes or other components, but to say heat does not promote aging defies the datasheets provided by many component manufacturers.

Plugging in vintage ham set and using it as is is the same as playing Russian Roulette... sometimes with a six shooter, but most likely with a 45 with the clip removed and a bullet in the chamber.

Pete


Title: RE: How hot does a Boat Anchor get?
Post by: G3RZP on February 09, 2015, 04:43:26 AM
It is arguable that there are components to which the heat/MTBF relationship applies and there are those  for which heat has little effect because of various design or manufacturing inadequacies - those will fail anyway, quite possibly if not even used. As an example, although hardly BA stuff, is tin whisker formation temperature related?


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 09, 2015, 04:53:24 AM
Metallurgy and compressive strength seem to be the leading causes. A lot of those problems appear to have peaked with  the lead-free environmental initiatives.  But, let's not get too political :)



Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 09, 2015, 05:01:19 AM

Strawman argument. Tom, you continue to use anecdotal personal observations passed off as factual information to deflect the issues.


Strawman argument from real life examples of dozens of radios I own?

Maybe you should not be so picky about someone's data while you are extracting one non-linear effect from complex data and trying to make it apply as a linear rule.  :)

(http://www.w8ji.com/images/Boatanchors/Homebrew%20transmitter/Capacitor%20life.jpg)



Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 09, 2015, 05:02:17 AM
It is arguable that there are components to which the heat/MTBF relationship applies and there are those  for which heat has little effect because of various design or manufacturing inadequacies - those will fail anyway, quite possibly if not even used. As an example, although hardly BA stuff, is tin whisker formation temperature related?

Peter RZP has both experience and common sense.


Title: RE: How hot does a Boat Anchor get?
Post by: G3RZP on February 09, 2015, 05:33:16 AM
I have even seen an equipment fail miserably on Type Approval because of electrolytic failure which was not related to heat or voltage........

A number of companies were producing 100 watt 2MHz marine SSB transceivers in 1971/2, and several of them went to the same DC-DC invertor manufacturer for their very similar power supplies. One part of Type Approval involved subjecting the equipment to vibration and bump testing: the bumps were 40 bumps of about 10g. Our equipment passed: our competitor's failed. In our case, the power supply was mounted such that the electrolytics were horizontal: theirs had the capacitors vertical and because the 'innards' were shorter than the can, vertical bumps meant the innards moved - no packing to stop them. Same capacitors.....

So it is to easy to generalise.......Some items are a bit easier - metal migration in integrated circuit metallisation is well documented at doubling for every 10 degree C rise in temperature. Now in many cases, even at 125 deg C, the current density is such that a life exceeding one or two hundred years is possible. But tunnel diodes, even if unused, have a life in generally in terms of tens of years because the very high doping density means that diffusion is happening at room temperature. So your AGM45 Shrike anti-radiation missile is probably no good by now.....On the other hand, we did a transistor array which was guaranteed to work for a minimum of 30 minutes at 260deg C - and charged accordingly!


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 09, 2015, 10:48:51 AM
True Peter, and I have seen numerous early Tantalum electrolytic caps used for bypasses fail, even though they weren't subjected to high ripple currents or varying DC voltages.  I've regrettably owned several Wavetek synthesized generators that would pop a tantalum on a voltage rail with great regularity. I eventually dumped them... no loss, they were massive noise generators and quite unsuited for any meaningful receiver measurements.

Pete


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 10, 2015, 03:33:16 AM
The strawman gives life to dead issues !

No one has said that heat is the ONLY cause for failure .  It is however a very well known and proven fact that heat is a factor in the premature failure of many components . Solid state to tube type .

  Anecdotes and shelf queen statistics cannot change that .


Title: RE: How hot does a Boat Anchor get?
Post by: G3RZP on February 10, 2015, 04:50:52 AM
A factor. By no means the only one, though.


Title: RE: How hot does a Boat Anchor get?
Post by: W8JI on February 10, 2015, 05:36:23 AM
The strawman gives life to dead issues !

No one has said that heat is the ONLY cause for failure .  It is however a very well known and proven fact that heat is a factor in the premature failure of many components . Solid state to tube type .

  Anecdotes and shelf queen statistics cannot change that .

Stop that silly stuff. This isn't high school.


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 10, 2015, 07:24:18 AM
I consider Tom to be a friend; I think friends can have disagreements and civil discussions.  While not always seeing eye to eye, friends usually remain friends and on good terms. Tom certainly knows more than I have forgotten in many areas.

Pete


Title: RE: How hot does a Boat Anchor get?
Post by: KC2QYM on February 10, 2015, 09:54:01 AM
I would say that if you smell some burning plastic or melting metal coming from your boat anchors you've exceeded the maximum thresholds.  I would occasionally place my hands on the top of the cabinets to ensure that the equipment isn't getting too hot.  Throw a few muffin fans on top to accelerate air flow exhaust.  How fancy do you want to be?  Your choice.


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 10, 2015, 09:59:40 AM
Plastic!!! On a boat anchor??  Heresy!  LOL 


Title: RE: How hot does a Boat Anchor get?
Post by: KD0REQ on February 10, 2015, 11:57:59 AM
phenolic.  it doesn't melt so much as it outgasses and shrinks into a nasty hot little ball of nasty.  you may also know it as bakelite and phenolic/fiber terminal strips.  there could also be vinyl wire insulation.  that can fail at tube-heat temperatures, while it pretty much takes a flame to take out phenolic.


Title: RE: How hot does a Boat Anchor get?
Post by: K1DA on February 10, 2015, 06:05:12 PM
I remember when Griefkits used a brown material for circuit boards in tube transceives such as the HW 12.  The stuff got sitcky and began to degrade around the two 6GE6 amplifer tubes. 
I began to use muffin type cooling fans  for such units back in the 60's. Now, the guts of a Collins 32S, for example, used components which were a lot more heat resistant.  Why, if Art didn't put a fan on it, it didn't NEED one.  The smell of hot dust was very common though.


Title: RE: How hot does a Boat Anchor get?
Post by: KG8LB on February 12, 2015, 04:47:58 AM

A factor. By no means the only one, though.

   And no one has said otherwise .   ;)  Although some try to make it seem they have .

 
The strawman gives life to dead issues !

No one has said that heat is the ONLY cause for failure .  It is however a very well known and proven fact that heat is a  factor in the premature failure of many components . Solid state to tube type .

  Anecdotes and shelf queen statistics cannot change that .

Stop that silly stuff. This isn't high school.

     Nothing silly about correcting your silly strawman distortions and sophomoric exaggerations of what has been said .


Title: RE: How hot does a Boat Anchor get?
Post by: KM1H on February 17, 2015, 09:44:11 AM
Id say that Pete, ZJH, is right on about the strawman comment since it was answered by nonsensical data not even remotely related; typical spin and confuse.
Pete also has a lot more experience actually doing a proper restoration and using than bragging about what is in storage and just looked at instead of regularly used.

The difference is obvious.

Carl


Title: RE: How hot does a Boat Anchor get?
Post by: AC2NZ on February 21, 2015, 09:05:13 AM
I have found some in expensive , quiet portable, controllable (simple switch on the fan) computer fans. I want to get some baseline figures. If I think any of them are running too hot for me I want to experiment by just putting the fans on the top of the cases (HK thoughtfully provides cases full of holes), and blow air over the tubes on a parallel axis. The fans are really quiet and I don't want to hack up the radios. I am particularly  interested in running an SB-301 and SB-401 (transmitter and receiver) on top of each other which may present heat problems.

Blowing cold air on a tube tends to shorten tube life. Use the fan to exhaust the heat. Blow cold air on a semiconductor; suck hot air off a tube.


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 21, 2015, 09:12:27 AM
I have found some in expensive , quiet portable, controllable (simple switch on the fan) computer fans. I want to get some baseline figures. If I think any of them are running too hot for me I want to experiment by just putting the fans on the top of the cases (HK thoughtfully provides cases full of holes), and blow air over the tubes on a parallel axis. The fans are really quiet and I don't want to hack up the radios. I am particularly  interested in running an SB-301 and SB-401 (transmitter and receiver) on top of each other which may present heat problems.

Blowing cold air on a tube tends to shorten tube life. Use the fan to exhaust the heat. Blow cold air on a semiconductor; suck hot air off a tube.

I guess Heathkit, Ten Tec, and many others had it wrong....


Title: RE: How hot does a Boat Anchor get?
Post by: KM1H on February 24, 2015, 02:38:18 PM
Try something that dumb on an 8877, 4-400A, 4-1000A, etc. Even some big pre WW2 TX tubes used a fan on the envelopes blowing room air.
Using a muffin fan on a pair of T4XC's extended 6jJB6 tube life from 6 months of serious DXing/contesting to several years.

After I reduced the AC line to my BA's to 108-113V the heat was no longer an issue.

Carl


Title: RE: How hot does a Boat Anchor get?
Post by: KC2QYM on February 27, 2015, 09:56:44 AM
Isn't the air drawing action of a top mounted fan over the tube doing the same thing as blowing air towards the tube?  The ambiant air still passes by the tube envelop at the same rate of speed. What's the difference?


Title: RE: How hot does a Boat Anchor get?
Post by: W1BR on February 27, 2015, 11:42:42 AM
Isn't the air drawing action of a top mounted fan over the tube doing the same thing as blowing air towards the tube?  The ambiant air still passes by the tube envelop at the same rate of speed. What's the difference?

No, not really... you have to remember that the pin seals also have to be cooled.  For example, many rigs running 3-500 tubes have the fans blowing across the tubes, which was designed adequate airflow over the base seals... otherwise the pins will melt, and also the socket fingers will overheat and weaken. I don't disagree that drawing air away from the capacitor banks and bleeders is a bad idea, however. 

Pete


Title: RE: How hot does a Boat Anchor get?
Post by: KM1H on February 27, 2015, 04:14:52 PM
The usual muffin fan blade design works best by pushing air; automotive fans excel at pulling air thru the radiator.

A fan in a radio with poor mechanical stability will be frequency modulated by the fans vibration.....many boatanchors are not very mechanically stable.

Ive added a small PC CPU fan under the chassis in several 12-16 tube console radios that ran extremely hot and even melted wax out of the various multiband coils. These radios all came wit several decent size chassis hole for the air to exit as well as move some hot tube air out of the cabinet. Since all these radios are for AM only there was no noticeable instability.

Carl


Title: RE: How hot does a Boat Anchor get?
Post by: KA4LFP on March 06, 2015, 07:36:46 PM

Kevin, I'm going to walk away from all the arguing on here about MTBF and heat....

Instead, I'm going to propose a way to do what you want to do, not argue about whether you should replace half the parts in your BA, and spend hours debating the MTBF of those parts.

There is a temperature sensor known as a DS18B20.
It's a little TO-3 (or TO-220) digital chip, with a Vcc (5v) and Gnd and Data pin.

Not sure how computer interested you are, but lots of us IT people use them for measuring temperatures inside servers or other cabinets, when we want to go DIY with it.

Here's a piece of Windows software that will use multiple DS18B20 devices, and graph the results over time - just like what you were asking for (and no one actually answered, unless it got lost in all the arguing)
http://www.mrsoft.fi/ohj01en.htm

Alternatively, if you want to go a bit more DIY, you can run a Raspberry PI with  Linux combined with an open source tool called MRTG (or RRDTool) that does a good job of reading temp sensors.
There are a lot of projects for doing that -- I've got  a Raspberry PI reading temp sensors
and graphing the results - total investment < $50 for 10 sensors and the PI.
Graphs show on a webpage delivered onto my network by the PI.
It requires some investment in learning, but what real ham doesn't want to learn!
(I'm sure I'll get flamed for saying that, since I'm sure there's an exception and he/she will loudly complain...)