Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: Prev 1 [2] 3 4 5 Next   Go Down
  Print  
Author Topic: How hot does a Boat Anchor get?  (Read 40524 times)
KD0ILM
Member

Posts: 55




Ignore
« Reply #15 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.
Logged
HFCRUSR
Member

Posts: 356




Ignore
« Reply #16 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.
« Last Edit: February 02, 2015, 01:56:16 PM by HFCRUSR » Logged

Not a ham, but an avid hobbyist in HF world. All things, short of transmit happen in this shack.
KD0ILM
Member

Posts: 55




Ignore
« Reply #17 on: February 02, 2015, 02:33:25 PM »

All good ideas
Logged
HFCRUSR
Member

Posts: 356




Ignore
« Reply #18 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 Tongue
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 Smiley
« Last Edit: February 02, 2015, 03:05:48 PM by HFCRUSR » Logged

Not a ham, but an avid hobbyist in HF world. All things, short of transmit happen in this shack.
KD0ILM
Member

Posts: 55




Ignore
« Reply #19 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.
Logged
KG8LB
Member

Posts: 408




Ignore
« Reply #20 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 .
Logged
W8JI
Member

Posts: 9748


WWW

Ignore
« Reply #21 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.
Logged
KG8LB
Member

Posts: 408




Ignore
« Reply #22 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
« Last Edit: February 04, 2015, 09:09:48 AM by KG8LB » Logged
KD0ILM
Member

Posts: 55




Ignore
« Reply #23 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
Logged
K8AXW
Member

Posts: 7037




Ignore
« Reply #24 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!
Logged

A Pessimist is Never Disappointed!
KG8LB
Member

Posts: 408




Ignore
« Reply #25 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 .
Logged
HFCRUSR
Member

Posts: 356




Ignore
« Reply #26 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.
Logged

Not a ham, but an avid hobbyist in HF world. All things, short of transmit happen in this shack.
K8AXW
Member

Posts: 7037




Ignore
« Reply #27 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.
Logged

A Pessimist is Never Disappointed!
KG8LB
Member

Posts: 408




Ignore
« Reply #28 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 . 

   
Logged
W8JI
Member

Posts: 9748


WWW

Ignore
« Reply #29 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.
Logged
Pages: Prev 1 [2] 3 4 5 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!