[R-390] 6082 Question-- Fans
Bob Camp
ham at cq.nu
Sun Jan 16 16:15:53 EST 2005
Hi
As long as the modification is no holes / reversible it sounds fine to
me.
I have heard stories that AC fans can have trouble (run hot) when run
at half voltage. I have never seen a problem but you do see notes about
it.
Take Care!
Bob Camp
KB8TQ
On Jan 16, 2005, at 2:23 PM, Dave or Debbie Metz wrote:
> 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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