[R-390] 6082 Question

[John KA1XC]

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