[R-390] 6082 Question

[Bob Camp]

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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