[R-390] Utah 3956

Thu, 25 Jul 2002 00:10:04 -0700

Anyone know what a Utah 3956 ballast is, or where it is used?  Somehow I
recall looking it up once, and finding it nowhere near the spec. of a 3TF7.
It is in a 7-pin miniature shell.

73 de Bill, AB6MT
[email protected]

----- Original Message -----
From: "Norman Ryan" <[email protected]>
To: "Glen Galati" <[email protected]>; <[email protected]>
Sent: Wednesday, July 24, 2002 9:39 PM
Subject: Re: [R-390] 6T4F

> Hi, Glen,
>
> Nice research!
>
> I have an Amperite TJ311M01 that measures cold at 13.3 Ohms DC
> resistance on my Fluke DMM 8024B.  I'm patiently waiting for it to
> exhaust so I can replace it with a 3TF7.  :-)
>
> All seriousness aside, the above ballast doesn't carry the designation
> "3TF7."  Thus the FEDLOG may have assigned a different NSN when the 3TF7
> appeared.  (I'm assuming 3TF7 is a newer designation for Amperite's
> catalogue number TJ311M01.)
>
> It came out of a spare IF deck.  I'm too lazy to pull my working R-390A
> out of its case to do voltage checks and substitution with a 3TF7 to see
> if the regulated tubes are getting similar voltage, but expect it's
> close enough for government work.
>
> The lettering is that notorious stuff that wipes off easily.  I couldn't
> make out that any lettering is gone.  What's there is is there-- that
> is, no smudges.
>
> Hope this helps.
>
> 73 de Norman KG4SWM
>
>
> Glen Galati wrote in part:
> >
> > Here is some interesting info on the the 3TF7 Current Limiting Resistor
as
> > specified for the R-390 Series. The FEDLOG description specifically
> > identifies this as Application = R-390/URR,  AC/DC, 0.040 to 0.260
Amperes,
> > 10.2 Volts Threshold,  9-Pin Miniature with T-6-1/2 envelope. NSN
> > 5905-00-259-1964, and was last procured $118.27. Measured DC Resistance
is
> > approximately 12-12.75 Ohms.
> > Now, here is an interesting twist to the story.  Amperite PN: TJ311M01,
NSN
> > 5905-00-681-4707; DC, Current Range 0.31 to 0.33 Amperes, 8.0 Volts
> > Threshold,  9-Pin Miniature with T-6-1/2 envelope. The FEDLOG states
"WHEN
> > EXHAUSTED USE 5905-00-259-1964" which is a 3TF7.  Hmmmmm! Makes you
> > wonder-What we really need here is to do a close scrutiny of the TM/TO's
for
> > the R-389, R-390, R-390A. and R-391 Part List and see what part number
and
> > stock number was listed.
> _______________________________________________
> R-390 mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/r-390