[R-390] Re: Ballast Tube Thread - on topic - Haa Haa - take thatagain ...

[Barry Hauser]

Bob wrote:
> So if a ballast tube is so important to making a stable radio that you
> can't even replace it with a herring then answer me this:
>
> We have the R-390A's dwarf midget child the R-392. The 392 is designed
> to be a mobile version of the 390. It runs directly off a jeep
> alternator. Last time I checked an alternator output it wandered around
> quite a bit depending on the speed of the motor.

Yup, that's why it's a "nominal" 24 volt system, yet the radio is rated for
28 volts, which is just about the max charging level of a 24v system.

 Both radios were
> supposed to do the same FSK stuff at roughly the same stability. The
> R-390A did it at a line voltage of say +/- 10%. The 392 did it at a
> supply between 22 and 32 volts.

Well, for one thing, R-392's are green.  By itself, that doesn't mean
anything, but it may be a clue.

> So why no ballast tube in the 392 ???? If one was needed that's the
> radio that should have gotten it. It didn't even get a herring ....

A herring -- yes a red herring - a clue!  Ever open up an R-392 that's been
sealed up a long time.  Peeeeeyoouuuuu!  I used to think that was the MFP.
Stinks like dead fish. Here's the scoop -- just figured it out right now:
You were there.

1.  R-392's are watertight and practically airtight.
2.  If you close 'em up cold, then they heat up (no vents) -- the air
expands and is diplaced by that stinky air stuff -- which may be some inert
gas, only .. I dunno -- smelly.
3.  After about 2 hrs the WHOLE RADIO turns into a ballast tube!  Y'see, as
the engine revs up and the voltage goes up to say 27 point something, the
26A7 heats up even more and .. well .. you see.

Notice, I didn't resort to Ohm's Law or any of that kind of trickery.

Actually, Bob, it's a good question, but the best I can offer is an idiotic
stoopid answer. Here's another:  The dastardly evil Ballast Tube Lobby
overlooked the R-392 because it was smaller -- and green, and below their
radar.  Otherwise they would have made the gov'mint stick a ballast tube in
them too.

Barry