UA78MGT4C IC SWITCH 63-269

[Mike Miller]

Hey all-
    I've managed to successfully retrofit an HWA2036-3 with an LM317.  My
supply had two parts wrong with it to begin with.  I first replaced the
417-224, an MPSU05, with an MPSU06, which is very similar.  I then subbed in
an LM317 for the UA78MGT4C regulator, since mine was bad.  I had to do some
pin-swapping of the two regulators, though, which wasn't any great
surprise - pin 1 (317) to pin 3 (UA78), pin 2 to pin 2, pin 3 (317) to pin 1
(UA78)...pin 4 of the UA78 location was left unconnected.  I noticed then
that my output voltage was high...variable, but high.  I reduced the 3900
ohm resistor (R5) to around 2700 ohms +/-.  You'll have to vary the
resistance of the replacement for R5 to get the voltage swing you desire.  I
put in the 2700 and was able to set my voltage right at 13.8.  I left the
supply on for around 20 minutes while watching the voltage on the meter, and
it didn't vary over .1 V or so.  This wasn't under load, but I'd suspect it
should remain fairly constant.  Anyone see any problems with this procedure?
        --Mike Miller, KA9RQW

----- Original Message -----
From: "Michael Tallent" <mtallent at CONCENTRIC.NET>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Friday, January 26, 2001 6:09 PM
Subject: Re: UA78MGT4C IC SWITCH 63-269


> This part is very hard to find, it has not been made in a long time as was
not
> very popular.  It is a Fairchild part, and I have a data sheet that I
could
> scan.  If somebody has a place to put it for downloading it would make it
easier
> for me to only send it one time.
>
> I would think that you could easily sub a LM317.  The 78MG part is a four
> terminal positive voltage regulator with .5 amp max load current.
>
> Mike Tallent W6MXV
>
> JBA wrote:
> >
> > The 442-626 was a 78MGT4C. It was an adjustable voltage regulator (POS).
I'm
> > not positive, but I think it may be obsolete now. I don't think ECG or
NEC
> > has a direct replacement for it anymore. Hopefully someone on the list
can
> > correct me and you'll be able to find one.
> > Good luck!
> > de Benton wb5twc
> >
> > ----- Original Message -----
> > From: "H. G. Jerry Dowell" <RECCOP18 at AOL.COM>
> > To: <HEATH at LISTSERV.TEMPE.GOV>
> > Sent: Friday, January 26, 2001 5:16 PM
> > Subject: UA78MGT4C IC SWITCH 63-269
> >
> > > In process of rebuilding a HWA-2036-3.  Need to acquire or be advised
of a
> > > replacement for the Part # 442-626 ( UA78MGT4C ) IC. Also need a
> > replacement
> > > off on switch for this unit. Part # 63-269. Thank you.
> > >
> > >     Again Soon
> > >
> > > Jerry Dowell
> > > WB0GYR
> > >
> > >
> > > H. G. Jerry Dowell
> > > 19119 / 201 E. Truman Rd.
> > > Independence, Missouri
> > > 64056-2432
> > > RECCOP18 at AOL.COM
> > > WB0GYR
> > >
> > > Listserver Subscription:listserv at listserv.tempe.gov - "subscribe heath
> > 'name' 'call'"
> > > Listserver Submissions: heath at listserv.tempe.gov
> > > Listserver Unsubscribe: listserv at listserv.tempe.gov - -"signoff heath"
> > >
> >
> > Listserver Subscription:listserv at listserv.tempe.gov - "subscribe heath
'name' 'call'"
> > Listserver Submissions: heath at listserv.tempe.gov
> > Listserver Unsubscribe: listserv at listserv.tempe.gov - -"signoff heath"
>
> Listserver Subscription:listserv at listserv.tempe.gov - "subscribe heath
'name' 'call'"
> Listserver Submissions: heath at listserv.tempe.gov
> Listserver Unsubscribe: listserv at listserv.tempe.gov - -"signoff heath"

Listserver Subscription:listserv at listserv.tempe.gov - "subscribe heath 'name' 'call'"
Listserver Submissions: heath at listserv.tempe.gov
Listserver Unsubscribe: listserv at listserv.tempe.gov - -"signoff heath"