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[Articles Home]  [Add Article]  

Can We Have a Quiet Shack?

from Ignacy Misztal, NO9E on March 16, 2017
View comments about this article!

Can We Have a Quiet Shack?

I dread noise, especially at home. Yet my shack can be full of it. A power supply with a high pitch, a transceiver after a minute of operation, and especially amplifiers can cause it. Often you feel you are in a machine shop. Is all that noise useful or is poor or unnecessarily safe engineering for 500 years mean time to failure...

The noise is coming from fans mostly cooling solid-state devices. Fans keep sink temperatures low, usually to about 50c max. Yet semiconductors can safely operate to 200c, even 250 if we allow for shorter (but still) long lifetime.

Many years ago I bought an MFJ power supply. It was small but the fan was irritating. I added a 3 position switch to control fan speed: Full for contesting, 1/4 speed (via zener diode) and off when listening. Accidentally I left the switch in the off position and the power supply failed after 10 years. Even after 5 it would have been a good deal.

I used to have a 500w solid-state amp made some 25 years ago. That amp did not have a fan, only a sink on top. When running, the sink was hot over boiling temperature but in 10 years until I sold it, it was fine. With that amp I rarely wore headphones.

Now I have EXPERT amps. The fans start operating at full speed at 40c. The max temp when running is 50c. One needs good headphones all the time. -- With other amps complaints galore. The exhaust is just warm and my shack is never warm even while contesting like it was with tube amps.

Assume that we allow for junction temperature 150c and the sink temperature is 50c. With ambient temperature 25c the fans need maintain a temperature gradient of 25c. Suppose we allow for junction temp of 200c, which will reduce mean time to failure from 10,000 years to 500 years. Then the sink temp can be 100c, temp gradient 75c, and the fans can run 3 times slower. One sacrifice made here is lower gain with higher temperatures. But we can easily compensate by increasing the drive a bit.

But we hear of radios overheating. For example drivers in some Icoms do it. But only because they do not have a good enough sink. So overly aggressive cooling can mask engineering errors.

If you have an old solid state amp or radio that you want to go to hell, slow down the fan first and see if anything happens.

So the next time you suffer from high noise don't think it is because you have to. Think poor or little engineering.

Member Comments:
This article has expired. No more comments may be added.
 
Can We Have a Quiet Shack?  
by W9PMZ on March 16, 2017 Mail this to a friend!
usually the volume control works wonders for ambient noise...

73,
Carl - W9PMZ
 
Can We Have a Quiet Shack?  
by KE4ZHN on March 16, 2017 Mail this to a friend!
To me it's more irritating to listen to fan noise in the other guys signal, than the fans in my own shack. Excessive mike gain is the bane of amateur radio.
 
RE: Can We Have a Quiet Shack?  
by AK4YH on March 16, 2017 Mail this to a friend!
Just stop using amps. You'd be surprised how well your radio works without one. If it doesn't you have an antenna problem.
 
RE: Can We Have a Quiet Shack?  
by W3TTT on March 16, 2017 Mail this to a friend!
by AK4YH on March 16, 2017 Mail this to a friend!
"Just stop using amps. You'd be surprised how well your radio works without one. If it doesn't you have an antenna problem...."

Reminds me of the guy, "Anybody driving faster than me is an idiot. Anybody driving slower than me is a moron."

Anybody using more power than me is . . .

But I agree completely with AK4YH on the power thing. I just participated with the NAQCC Sprint with my Small Wonder 40 which has a whopping output of ONE WATT. I contacted Washington State and British Columbia, over 3000 miles from Baltimore. Not. Bad. And I enjoyed it too!

"Ham Radio - the most fun you can have while sitting down..."

73, respectfully
Joe
 
RE: Can We Have a Quiet Shack?  
by W4KVU on March 16, 2017 Mail this to a friend!
usually the volume control works wonders for ambient noise...

73,
Carl - W9PMZ
The on/off switch is more effective...
 
Can We Have a Quiet Shack?  
by W4XKE on March 16, 2017 Mail this to a friend!
Most electronics engineers will tell you that the biggest killer of electronics components is HEAT! I like to keep things cool. If the fan causes too much noise, I put a duct on the intake to act as a muffler or just move the annoyance a bit further away from my receiver.

On the topic of hot radios - I had an Icom 706MKIIG for a while and that was one HOT rig! While it didn't fail while I had it, it always worried me that it would. I sold it before it cooked something and so I was able to relax after it was gone.
 
RE: Can We Have a Quiet Shack?  
by K6AER on March 16, 2017 Mail this to a friend!
The more you cook solid state devices the shorter their useful life is. Letting devices (power transistors and FET's) get to 160 degrees "F" can reduce the MTBF (Mean Time Between Failure) from 40,000 hours to under 1000 hours.

Providing a fresh air vent for cool air to be brought into the equipment area will help greatly.

I am envious that you have hearing good enough to hear a fan.

I set my microphone gain by looking at the watt meter and set the audio for maximum dynamic range.
generally it is about 45 dB.
 
Fans can be quiet.  
by KK5JY on March 16, 2017 Mail this to a friend!
I'm amazed at some of the junky fans that amplifier manufacturers pick. There are some really high-quality fans out there that can move a lot of air without making a lot of fuss while they run. But that's not what makes it on to new ham gear. I was surprised to learn that my new ACOM amplifier uses a squirrel-cage blower to move air across the tube. They used a resistor to slow it down, but still, that's not a quiet choice.

*All* of the amplifier fans I have seen on modern gear, even on very expensive units, are the cheapest, plastic, mass-production fans they could find. Until hams start demanding more from their amplifier manufacturers when they lay down $2k for a nice amp, the poor part selection will probably continue.
 
RE: Fans can be quiet.  
by NI0C on March 16, 2017 Mail this to a friend!
Noise cancelling headphones work well for me. I almost never use speakers in my shack.
 
RE: Fans can be quiet.  
by AF6AU on March 16, 2017 Mail this to a friend!
Some fans in gear are made noisey by having their airflows blocked by close positioned partitions or "Screens" made by punching out slots in the chassis or sheet metal cover. Take a needle nose plier, and bend/rotate those flat areas 90 degrees so they align with the airflow, and it will make the fan quieter with better airflow over the blades. The old kenwood 520, 820, and 830, as well as old tube final Yaesu's were notorious for this.

Fans with a load of dirt on the blades are also noisey, clean them once every couple years... Clean filers as well, a load of dust makes the blades pulse and create more noise.

It is also easy to make simple relay or Mosfet switches to upspeed the fans with key-up, and idle them with receive. You can also go fancy with thermocouples and associated circuits, but staging with key-up is easy. Some things like linears running fat vacuum tubes need cooling all the time, but by using a cheap infared thermometer to see idle tube tempeature verses transmitting full QRO, you can stage many of their fans as well. Pay attention though, classic tubes like 4-400's, 3-500Z's, 3-1000's and others need tube base cooling or you will melt the pin's soldering with just filament power.

Fan noise can be dealt with, first chore is finding out what is causing the fan to be noisy, it just may be a load of the Kittie's or Fido's fur in the filter and on the fan blades.

I had a friend with an overheating computer that when I opened it up, it was loaded with carpet cleaning powder! The XYL loved the smell of "Fresh Carpets". The powder ruined all the fan bearings by absorbing the oil, and totally plugged the CPU and video card fans and heat sinks. The computer failed when the power supply fan stopped.

 
Can We Have a Quiet Shack?  
by WA3SKN on March 16, 2017 Mail this to a friend!
If fans are your noise source, eliminate the fans.
There is nothing wrong with liquid cooling, or even a LARGE heat sink.

-Mike.
 
Can We Have a Quiet Shack?  
by N9DG on March 16, 2017 Mail this to a friend!
My solution that I got to implement when I built a new house and therefore a new basement shack a few years ago was to build a shack with an equipment wall that has walk behind access its entire length. Then on the far side of the equipment wall and access ally there is a sound barrier wall, actually a curtain. On the other side of that sound barrier wall is where all the equipment goes that has fans in it, including all of the computer gear and so on. All that gear is located on a beefy industrial-ish standalone shelving unit.

I also hung some sound absorber foam panels like you find in recording studios within the server room to mostly suppress the higher frequencies while the floor to ceiling curtain wall does does more with the lower frequency sounds..

It is basically a server room for my gear that is shared with the furnace that also makes plenty of noise. Almost all of my gear that has fans in it has been banished from the operating area of the shack completely and into the server room. And now I purposely avoid buying any new gear that has fans in it, and/or that cannot be remoted to a least 8 to 10 feet away from the operating position. Ethernet connected gear is wonderful for achieving this.

So I simply let all the fans do exactly what they are meant to do to keep the gear cool without modification. And just physically isolate it away from where I am operating from.

All in all it has been working out very well. The shack operating area side of the equipment wall is almost fan noise free. And I even find myself contemplating moving the linear power supplies with their persistent hum they have. Overall it is now the other noises of the household that dominates what the non-radio audio sounds are heard in the shack. I could do more room noise control work for the shack operating area itself, but so far havenít done so.
 
RE: Can We Have a Quiet Shack?  
by AC7CW on March 16, 2017 Mail this to a friend!
Passive Heat pumps are kind of interesting. They make no noise at all. They use a heat conducting fluid that flows due to the heat difference between the device being cooled and a heatsink at the other end of said heat pump. They are powered by energy lost as heat so there is an overall efficiency gain.
 
RE: Can We Have a Quiet Shack?  
by AC7CW on March 16, 2017 Mail this to a friend!
Peltier junctions can be used for cooling. They make no noise at all. The downside is that they require large amounts of DC current.
 
RE: Can We Have a Quiet Shack?  
by ONAIR on March 16, 2017 Mail this to a friend!
Quietpc.com features virtually noiseless fans for computers. They can be used in ham gear as well.
 
RE: Can We Have a Quiet Shack?  
by AF5CC on March 16, 2017 Mail this to a friend!
Fan noise is the least of my worries. My house just isn't that quiet, and fan noise doesn't bother me. I hate to listen to noise on the bands, though, due to all of the RFI coming from cheap consumer crud in the neighborhood.
 
Can We Have a Quiet Shack?  
by N6JSX on March 16, 2017 Mail this to a friend!
OMG, does no one realize radio fans are sized for the location and >cheapness< to provide only enough cooling to keep the radio to live just past the warranty period!

You really think the radio MFG cares about life past warranty? Then why has Kwood FM VHF/UHF radios states high power max OPs = TX-1min & no-TX-3min? Since the TM-631/731 series the VSWR protection circuitry was removed (PCB still had the traces but no components)- TX-meter has become just a function of PTT and the selected power level - NOT VSWR or real POWER OUT. Since 1989 when Kwood stuck us with the VSWR-meter hoax ALL MFG's have now done the same - it's just economics/cheaper. I digress, back to subject.

It is not always the fan motor that causes noise, it can be air-flow via the running RPM and blade pitch or number of blades. Some times reducing fan Voltage/RPMs can greatly reduce air noise and still not compromise the circuit CFM/BTU needs. Often MFG's install a fan that is way over kill but is the cheapest!

A push-pull dual-fan combo can often give what is needed at a lower CFM/air-flow.

There are so many fans of all sizes, blades, pitches, voltages, RPM; you do not like the fan noise SUBSTITUTE or better listen to the rig BEFORE buying and avoid the noise crisis.

Try air ducting that can act as a noise muffler but the trade-off is in reduced CFM/air-flow. Increasing heat-sink size is not always the answer if there is still inadequate ambient air-flow to pull the BTU's off the sinks. How much air actually moves behind a crowded radio stack on the desk/shelf? Not much! Most have barely enough room to hook up the coaxes.

The next fan hoax is how the fan gets turned on, cheapest is via PTT CPU timing, the more expensive and proper method is via a thermal switch(s), guess which one is becoming more common in HAM gear?

Is this a technical hobby or not? Don't like the noise then experiment, substitute, modify, investigate, and read about EE thermodynamics.
 
check semi spec sheets. life goes down after 27 C  
by KD0REQ on March 17, 2017 Mail this to a friend!
every semiconductor spec sheet I've seen (well, OK, most are so old they're carved in stone) shows 20 to 27 degrees C as the reference point. and component life as they heat up goes down in a straight line from there, to 80 or 100 C being 0 hours. not 200 C. 20 is more or less room temp, 100 degrees Celsius is the point at which water boils. so I still believe in fans. discrete components have similar curves if you look them up as well. my rule of thumb has been for decades if you put your hand on the machine and can't hold it there ten seconds, it's already in trouble.
 
RE: check semi spec sheets. life goes down after 27 C  
by KB1GMX on March 17, 2017 Mail this to a friend!
If your fans are noisy then fix or replace them.

Running sold state devices hot shortens their life and the it doesn't take much of an increase in activation energy for increased failure rate.

While the solid state stuff tolerates a lot of heat the various other components are subject to that heat especially electrolytic caps (105C is too hot).

Better speed controls for fans, better airflow paths
help greatly. Some changes I've made that help.

Swiss cheese grills (many small holes) cut them open and replace with a fan grill guard.

Better quality fan of the same airflow, some are very noisy due to cavitation of the air. A better blade shape usually gets more airflow and lower noise.

Airflow inside the gear, make sure its doing the intended job and not loosing cooling through mounting holes or other useless paths. Add baffles as needed.

Suck vs blow, seriously. Having air blown out the front toward the user is not comfortable and can be noisier due to exhaust grills. Some cases using two fans slowed but one sucking in and the other forcing exhaust can be more effective.

Insure the internal area are not filled with lint, dust, and animal hair as they impede cooling and for gear with speed controls force to faster/noisier.

Move the gear further away. I don't need my solidstate amps right in from of me and the mic.
If switches and tuning are needed tehy can be close enough for that but not in the middle of the equipment group.

Allison
 
RE: Can We Have a Quiet Shack?  
by KE7FD on March 17, 2017 Mail this to a friend!
Video gamers often use water cooled CPU's. While I'm not suggesting that everyone run out and replace their fans with copper tubing, keep in mind that if a water cooler leaks in a PC it's going to toast a pretty expensive computer so those cooling units have to be leak proof. My little dual band radio that I use in the shack (Yeasu) turns the fan on no matter what the power level is. Since itís a fixed radio I might get away by adding massively large fins that don't interfere with other stuff around it, and remove the fan. Commercial stations use (always/often?) liquid cooling if not forced air on a massive scale but the studio isnít in the same room either. Seems if the noise is bugging you (like my little Yeasu does me), thereís a better way to solve the problem than putting up with noisy fans. I will say that I mounted a large and very quiet PC fan over the memory sticks (replaced the side panel with MDF) of one of my PCís. You donít even know itís on AND the PC runs very cool now. So, it is possible to find quieter fans that are intended for purposes other than ďover the counterĒ stock fans built into our gear.

But if your gear is still under warranty, training a monkey to wave a fan over the heat sinks might be your best option.

IMHO,
Glen Ė KE7FD
 
Can We Have a Quiet Shack?  
by AH7I on March 17, 2017 Mail this to a friend!
Let's see.

Because HVAC expensive, my windows are usually open.

Honolulu it's mopeds, parrots, dog barks, roosters/chickens and those incessant morning doves.

Atlanta it's sirens(ambulance, police, fire), racing motorcycles at 3AM, dog barks, roosters/chickens, gunshots, and mocking birds who have adopted the backup warning tone from the garbage truck.

73, -Bob ah7i/w4 Honolulu/atlanta

 
RE: Can We Have a Quiet Shack?  
by W0WUG on March 18, 2017 Mail this to a friend!
"and mocking birds who have adopted the backup warning tone from the garbage truck.
73, -Bob ah7i/w4 Honolulu/atlanta"

Mocking Birds, hahaha, funny. Maybe one of those could be trained to call CQ during a contest. :D
73/W0Wild Ugly Gorilla
 
RE: Can We Have a Quiet Shack?  
by KG4YMC on March 18, 2017 Mail this to a friend!
You didn't. Go to enough rock concerts when younger ?high frquecy hearing loss will take care of the noise .lol hearing aids with directional mikes non issue
 
RE: Can We Have a Quiet Shack?  
by W4HM on March 19, 2017 Mail this to a friend!
Most ham's that don't have a amplifier don't because they cant afford it.
 
Can We Have a Quiet Shack?  
by K1DA on March 19, 2017 Mail this to a friend!
Try working JA's on 75 SSB without an amp. No amount of QRP "magic" will overcome the path loss or the ORM at the other end. You might do it on CW with a giant antenna system, but an amp's cheaper and it will stay up all winter.
 
Can We Have a Quiet Shack?  
by WD9IDV on March 23, 2017 Mail this to a friend!
Can We Have a Quiet Shack? No!
 
Can We Have a Quiet Shack?  
by KC2MMI on March 23, 2017 Mail this to a friend!
As others have mentioned videogamers (and before them power users) have found solutions in computers for a long time. Peltier chips, liquid cooling, even in some laptops little Freon-filled pipes that ran out to heat sinks, no motors used.

The way I was given the math is this. Without seeing the MTBF figures for the specific devices, the USAF used a rule of thumb that solid-state semiconductors could run for 100 years in a "properly engineered" circuit. Ideally they would run close to 20C which is room temperature. And for every 10C gain in temperature, you cut the expected life in half. So, 20C to 100C? That's a 2^8th reduction. To 160C that's a 2^14th reduction in life. If I have the math right (often don't) that's a 16,834x reduction in life.

From 100 years (36,500 days) to about 2-1/2 days at 160C. Or to 102 days at 100C. (That's days of use, hours of operation would be more meaningful...let's so 60 hours and 2400 hours, roughly?)

Even though those are ballpark numbers and my math needs to be checked...they should give you a rough idea of why you want components to run COLD. Not just "cool enough" but COLD if at all possible.

Which is also why computer server farms tend to be air conditioned to the painful point.

100 years versus 100 day$.

FWIW, Rotron (owners of the "Muffin" etc. fan trademarks) used to have about four pages just for 12v fans in their catalogue. Each rated with specs that include the db rating of the fan. Cheap fan blades can literally double the noise that a fan makes, so it can be very satisfying simply to look for a replacement fan that is going to cost a bit more than the $2 OEM one did, but will be much quieter, and have a higher airflow as well.
 
Can We Have a Quiet Shack?  
by AC7GO on March 25, 2017 Mail this to a friend!
Over-design is often a factor. Without access to simulators and the original design schematics, it's not easy to predict how much over-design is in play. A person can experiment, just as the author did. His amplifier had substantial over-design for temperature. Not all will. And variations in processing of identical parts coming from a single device manufacturer or substitutions of parts from different manufacturers can eat into design margins.

The comments about some fans being quieter than others are great. Modern turbo fan engines on airliners are much quiter than older engines without bypass, in which thrust is derived mainly from exhaust. Better blades on muffin fans are much quieter.

Great article. By the way, I hate noise, too.
 
Can We Have a Quiet Shack?  
by W1XYZ on March 27, 2017 Mail this to a friend!
I hate noise of all kinds. Hey why don't you send that Expert Amp over here? I'll send you something much less noisy back.
 
RE: Can We Have a Quiet Shack?  
by KG7YSE on April 6, 2017 Mail this to a friend!
Usually the noisiest thing in my shack is my wife. I love her but it never fails when I home in on a weak signal, she picks that time to start talking....
 
Can We Have a Quiet Shack?  
by N3ZY on April 13, 2017 Mail this to a friend!
I think this article provides poor advice. Running temperature generally has a strong effect on long-term reliability. Many passive components, especially capacitors, exhibit a drastically shortened life span when subjected to higher temperatures. Failures of electrolytic capacitors, which is common in older equipment will often cause failure of other, much more expensive components such as power transistors and transformers. They can also leak and actually corrode away circuit board traces and other components. If I were considering a piece of used equipment and I knew that the owner had disabled the fan or reduced the fan speed without other compensatory measures, I would not buy it.

Most active components are pretty robust and don't fail unless they are abusedin some way. When they do fail, the most common reason is the failure of another component that causes them to be operated out of specification.
 
Can We Have a Quiet Shack?  
by KF7KIM on April 15, 2017 Mail this to a friend!
My shack noise sounds like Bacon Frying sometimes 20 over, any suggestions . JB KF7KIM
 
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