[R-390] R-390 slugs

[Jim Temple]

Although my R-390 non-a appears to have the correct complement of
slugs/coils, there is a good possibility of mismatch in many of the R-390's
out there.  This is due to the fact that, at least in early production run
R-390's, three disticttly different slugs were installed.

I have read archive reports of alignment and sensitivity issues that seem
likely to be caused by slug mis-matching.  I, personally, corrected an
alignment problem after noticing the color dots on the slugs, and correctly
exchanging slugs to match the color code reported by previous archive posts.
Now my R-390 has a consistent match of color dots within coil banks and the
sensitivity matches my R-390A.

In correlating archive posts, personal observation, and the Final
Engineering Report for R-390, the correlation consistently supports the
following:

1.  In early production run R-390's, three different slugs were installed,
and one type slug was installed in all positions of a given coil bank.

2.  The color dots correlated to the following slug/coil banks:

RF....
.5-1, 1-2, 2-4    S-51 iron, Yellow dot.
4-8                  S-62 iron, Red dot.
8-16, 16-32      S-100A,    Blue dot.

Variable IF...
3-2                  S-62 iron,  Red dot.
18-9                S-100A,     Blue dot.

In the 1962 TM 11-5820-357-35, page 3 notes that begining with RF subchassis
MOD 2, the slugs of the antenna coils were changed to a different material
and the size of the slug in the 16-32 coil bank were reduced in size.

Hope this helps with tracking down the R-390 non-a coil/slug investigation.
Let me know if anyone agrees or disagrees.

Jim

----- Original Message -----
From: "Jordan" <jordana@nucleus.com>
To: "Mark Masin" <mmasin@atc-us.com>
Cc: "Jim Temple" <jetemp@insightbb.com>; <r-390@mailman.qth.net>
Sent: Monday, May 06, 2002 10:47 PM
Subject: Re: [R-390] R-390 slugs


> I do recall there was a note I read many years ago that mentioned the fact
that
> some of the cores would not allow for proper tracking , especially on the
16-32
> Mhz slug rack range...I'm not too sure where I read this , but I do recall
seeing
> a notice regarding this... 73 de Jordan..
>
> Mark Masin wrote:
>
> > Who is the manufacturer of the coils that have these cores? Also what
are the
> > Signal Corp drawing numbers of the transformers? Perhaps I can help
clear up
> > this mystery.
> >
> > Mark Masin
> > American Trans-Coil
> >
.qth.net/mailman/listinfo/r-390
>