[R-390] 6082 Question

[Bob Camp]

Hi

One of the recurring threads on the 390(not an A) is the power that 
goes into the regulators. The power can warm up the radio. Things can 
get pretty warm in a restricted airflow situation.

Dropping from 24 to 12 volts with a linear regulator will dump more 
power into the radio. It will also pull more current out of the 
filament transformer. You need the same filament power at 24 or at 12 
volts. That makes for 2X the current at 12 volts as at 24 volts.

Needless to say there are a variety of odd thing done to try to address 
the 6082 situation. I guess I'd rather mail out a couple 6082's than 
get into more off the wall mods to these radios right now.

Every so often 6082's show up at auction for reasonable prices. I 
totally agree that the "normal" asking price for these parts is a bit 
more than I think it is reasonable to pay.

	Take Care!

		Bob Camp
		KB8TQ

On Jan 15, 2005, at 12:59 PM, David C. Hallam wrote:

> Well, let's put it this way.  It won't harm the radio any, it's easily
> reversible, and if you want to improve on it, I guess you could 
> substitute a
> 3 terminal 12 volt regulator for the diode.
>
> David
> KC2JD
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net 
> [mailto:r-390-bounces at mailman.qth.net]On
> Behalf Of John KA1XC
> Sent: Saturday, January 15, 2005 12:36 PM
> To: R-390 reflector
> Subject: Re: [R-390] 6082 Question
>
> Hi Dave, well I wouldn't go so far as to say that it is a "standard 
> mod"
> just because old A.J.C. wrote up his mods on MARS letterhead, and I 
> haven't
> seen any of his mods done (fortunately) to any 390s or 391s to cross my
> path, even my latest 390 that has a colorful MARS decal on the front 
> panel.
> This mod was not authorized by Collins or the Military, and he even 
> included
> the disclaimer "The Author, however,assumes no responsibility for the
> operation of these circuits."
>
> My beef  is that his 6082 conversion method is seriously flawed. He
> substitutes a pair of 6080s with series connected filaments (fine) but 
> then
> attempts to derive the required 12 V RMS for the filaments by half-wave
> rectifying the 25 VAC (incorrect). This is a common error in 
> electronics
> thinking which actually puts about 50% more RMS volts (emphasis on the 
> RMS)
> on the filament string. Yes, they will work like this for a time but 
> the
> 6080 filaments are getting *seriously* cooked.
>
> As usual this topic has been cussed and discussed here before, just 
> poke
> around the archives for any posts on relating to 6080, 6082, or 
> ballast tube
> voltage conversions, same problem applies to them as well. I just hate 
> to
> see any R-390s abused by a bad mod and wish that this particular one 
> would
> stop propagating through cyberspace ;^)
>
> R-390 Archives => http://mailman.qth.net/pipermail/r-390/
>
> 73,
> John
>
> ----- Original Message -----
> From: "David C. Hallam" <dhallam at rapidsys.com>
> To: "Tom Norris" <r390a at bellsouth.net>; <R-390 at mailman.qth.net>
> Sent: Saturday, January 15, 2005 10:40 AM
> Subject: RE: [R-390] 6082 Question
>
>
>> The substitution of 6080's for 6082's is a standard modification for 
>> the
>> R-390.  Details are explained in A. J. Carmody's R-390 Cookbook.
>>
>> David C. Hallam
>> KC2JD
>
>
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