[R-390] 6082 Question-- Fans

Sun Jan 16 14:23:30 EST 2005

At the risk of the sharp tongues, here goes. I added a 220v muffin fan to 
blow on those hot devils and run it on 120v. Very quiet and solves a big 
problem. However, one needs to make room for it so my solution was to 
remove the big electrolyitc and replace it with a new modern version that 
was much reduced size. It's been running that way for at least 5 years 
about 6 months at a time and no failures.  The "replaced" cap is carefully 
stowed away for future generations but in the mean time, I want to use it 
without concerns as to heat which the signal corps knew was a problem from 
almost day one.
73's
dave

At 10:58 AM 1/16/2005, Bob Camp wrote:
>Hi
>
>A fan is not a bad idea at all. The main issues with one seem to be noise 
>and how to mount it.  Probably the only better idea is two fans (one above 
>and one below the radio).
>
>These days you can get fans that are pretty quiet acoustically. One of the 
>common things to do seems to be to run a DC fan at half it's rated 
>voltage. The air flow goes down quite a bit at half voltage but you don't 
>need a hurricane to cool off a R-390. About all that leaves is RF noise 
>from the fan....
>
>Coming up with a way to mount the fans without cutting up the radio is an 
>important part of the process. I can see no reason to chop holes in the 
>radio simply for cooling, though that has been suggested in the past. One 
>way or another you would need to come up with an external mount for the 
>fans. Simply setting them on the radio sounds like an accident in the 
>making ....
>
>Air flow at least takes the temperature of the top of the modules down. It 
>indirectly impacts the temperature inside the module as well. That said 
>there's still some heat inside the modules.
>
>There are a couple of high power resistors in the cathode's of the 6082's 
>that seem to run a bit hot. Often these are reported as being well out of 
>tolerance (like say 2 or 3X the rated value). If you do replace them 
>recommendations have been made in the past to bump up the dissipation 
>rating of these parts. Obviously the resulting radio would not be "100% 
>natural / organically grown".
>
>A lot of this comes down to what your objective is. Everybody would love 
>to have a 100% original radio and have it work perfectly in all respects 
>24/7. Those of us without access to 100's of radios  may have to choose 
>between one or the other.
>
>         Take Care
>
>                 Bob Camp
>                 KB8TQ
>
>
>On Jan 15, 2005, at 10:01 AM, Michael Murphy wrote:
>
>>True Bob,
>>
>>An efficient switcher running at a nice high frequency like say 455 kHz -
>>could double as a BFO?.. hmm
>>
>>How about a combined 100 kHz power supply marker generator?
>>
>>Speaking of heat, My ART-13 would melt if I did not do something to get the
>>heat out. The design is just too darned tight and the 813, 811's and 1625's
>>really heat up when the thing is in standby at the higher (450 VDC medium
>>voltage and High V 1500V) that I run . If I was in a B-24 at 12000 feet I
>>suspect all would be OK.  I will admit it - I use a big-ol muffin fan with a
>>sand resistor in series with it to slow it down a bit, blowing out. Keeps
>>the radio cool and helps to heat the radio shack and best of all the tubes
>>have never had to be replaced. Why not apply this primitive approach to the
>>R390 series?
>>
>>Mike Murphy WB2UID
>>
>>----- Original Message -----
>>From: "Bob Camp" <ham at cq.nu>
>>To: "Kenneth G. Gordon" <kgordon at moscow.com>; "R-390 HF Receiver List"
>><r-390 at mailman.qth.net>
>>Sent: Saturday, January 15, 2005 11:11 PM
>>Subject: Re: [R-390] 6082 Question
>>
>>
>>>Hi
>>>
>>>Well the main way you get the power out is to use regulating devices
>>>that do not have filaments in them. That puts it more in the category
>>>of redesign rather than modification.
>>>
>>>I hope that doesn't stir anything more up.
>>>
>>>Take Care!
>>>
>>>Bob Camp
>>>KB8TQ
>>>
>>>
>>>On Jan 15, 2005, at 3:06 PM, Kenneth G. Gordon wrote:
>>>
>>>>Dave Metz wrote:
>>>>
>>>>>Tom,
>>>>>There is an article in Hollow State Newsletter within the last couple
>>>>>of
>>>>>years detailing a conversion that eliminates them and the huge heat
>>>>>they
>>>>>create. By Dr. Jerry
>>>>>dave
>>>>
>>>>Sigh...I sure wish I had known that when I still owned an R-390/URR,
>>>>serial number 21. I had to replace two charred sockets once. I was
>>>>amazed at the heat those things put out, especially when they were
>>>>gassy.
>>>>
>>>>Ken W7EKB
>>>>_____________________________________________________________
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>
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