[R-390] 390() vs 390(A)

[Barry Hauser]

Hi John & list

As we approach the new year, it is only appropriate that we, once again,
contemplate the differences of the R-390A and the original version, the
R-390, referred to in certain circles as the "non-A" for clarity's sake.
However, this appelation tends to offend some on the basis of logic, and
possibly some deep existential sensibilities.

Further influencing the situation -- the two receivers are very similar -- 
but very different -- simultaneously.

To tell the difference (given no tag or "nomenclature plate") the easiest
thing to spot is the position of the antenna trimmer.  If it's top dead
center of the panel -- it's an "A".  If not, not.  There are some
differences on the back panel -- the "A" has two terminals for the power
cord with a metal cover if it isn't missing.  The R-390 has a round,
four-pin connector for a removeable cable.

There are a number of other outside differences.  While the conversion
scheme is basically the same, there is not a single module which is directly
interchangeable.  While some tubes are in common -- like twin 26Z5W's for
rectifiers, the famous 3TF7 ballast (if not subbed out), much of the tube
lineup is different and the overall tube count is higher, including a pair
of 6082 regulators in the R-390.

One of the differences of primary interest to most -- The R-390 has L/C
filtering, no mechanical filters.  The R-390A has four mechanical filters.
In the past, that has made the "A" version more popular -- and the fact that
several times more "A"s were manufactured over the years from the early
fifties, through the late 60's and a few in the 80's.  R-390's were made in
the early 50's, ending in '53, as I recall.  There is a hybrid variant -- 
R-725? -- basically an "A" with a non-A IF deck.

There is also the R-391, which is basically the same as an R-390 with an
electromechanical autotune mechanism added.  There is an extra 8-channel
knob, little window showing the current channel and special MC and KC knobs
with locking keys.

So ... which do you have?  What are the other three?

Happy Chrismas and Merry New Year to all.  (think about it ;-)

Barry






----- Original Message ----- 
From: "John Lawson" <jpl15 at panix.com>
To: <r-390 at mailman.qth.net>
Sent: Sunday, December 26, 2004 5:40 PM
Subject: [R-390] 390() vs 390(A)


>
>    I have a nice old girl of a 390 that I purchased about six months ago.
> It needs a good chunk of TLC and some elbow-grease, but it's basically a
> working radio and it's in daily use.
>
>   However, it arrived sans it's rating plate, and I have yet to do more
> with it other than hook it up and listen to it.
>
>    I have most (if not all) of the pertinent docs and manuals, paper and
> CDROM, and this is my 3rd R-390 in the last 30 years.
>
>   My specific question is: is there a quick-and-dirty way to determine if
> one has a 390() or 390(A) from examination alone?  I'm just not up on the
> differences enough to figure this out all by my lonesome.
>
>    I'm just in the last stages of restoring my R-388/51-J [Collins, sn
> 258], and when the front panel comes back from Howard Mills I'll turn my
> attentions to the 390.
>
> Cheers and best of the Season!
>
>
> John  KB6SCO
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