[R-390] R-390A IF deck caps in T501 or T502

Tue Jan 15 21:17:56 EST 2019

Thank you all for the valuable input.

I had about 20 new silver mica dog bone caps and of course not a 200 in the
lot.  I did however, have a couple of choices to make up 200 for testing.
When I first determined that input (B+) side would not peak, I removed both
caps, the 200 and the 39.  I did find 2 that I could use for 240 pf, so
they are in there 'dangling' since yesterday when you all told me the one
was 200 (thanks so much for that).  And guess what - not a peep of gain
instability.

I think my plan is to put the 39 pf back in because it is most likely the
temp compensator and not the problem.  Then a couple more days of off and
on testing to make sure it's ok during warm up.  If all goes well as
planned, I'm going to replace the other 3 SMs in these 2 IFs and then look
at T503 and Z503.

Since this is a 1962 contract amelco, this silver mica lasted about 57
years.

More in a few days.

Regards, Larry

On Tue, Jan 15, 2019 at 1:27 PM Moe Fretz <tubetester at gmail.com> wrote:

> Can't beat justradios
>
>
> On Tue, Jan 15, 2019, 16:23 <hamfish at comcast.net wrote:
>
> > Just looked today at some of the other suppliers. DigiKey & Newark want a
> > minimum order of a 100 caps. Mouser today is out of stock, I tried their
> > shopping cart and it took an order of 4. Think it was a 10 week wait.
> YMMV
> >
> > Craig,
> >
> > -----Original Message-----
> > From: Dan Merz <mdmerz at frontier.com>
> > Sent: Tuesday, January 15, 2019 11:24 AM
> > To: hamfish at comcast.net
> > Cc: Larry H <larry41gm at gmail.com>; R-390 Forum <r-390 at mailman.qth.net>
> > Subject: Re: [R-390] R-390A IF deck caps in T501 or T502
> >
> > Is there some reason not to buy sm 200 pf from JustRadios for 89 cents
> > each?  Of course, they have min order of $20 but there’s always something
> > else you might want. Dan
> >
> > Sent from my iPad Air2
> >
> > > On Jan 14, 2019, at 6:04 PM, <hamfish at comcast.net> <
> hamfish at comcast.net>
> > wrote:
> > >
> > > Hello Larry,
> > >
> > > Mouser has them. I took a look this afternoon, not cheap about $9 and a
> > few more pennies each.
> > >
> > > Regards,
> > > Craig
> > >
> > >
> > > -----Original Message-----
> > > From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On
> > > Behalf Of Larry H
> > > Sent: Monday, January 14, 2019 2:38 PM
> > > To: R-390 Forum <r-390 at mailman.qth.net>
> > > Subject: Re: [R-390] R-390A IF deck caps in T501 or T502
> > >
> > > Thank you all for the help on this. I would never been able to get
> those
> > other numbers from my 4 mica caps (2 in each xformer).  200 pf makes good
> > sense.  Now if I can find one.  Thanks again.
> > >
> > > Regards, Larry
> > >
> > >> On Mon, Jan 14, 2019 at 9:11 AM <hamfish at comcast.net> wrote:
> > >>
> > >> Jacques,
> > >>
> > >> Old brains and a slow pencil. Then toss in the keyboard. Had to use a
> > >> spot light & magnifying glass to see what is behind the metal strip.
> > >> Back & forth looking at all four mica caps located in the
> > >> transformers can be great fun.
> > >> Thanks for your information on values. I'll pencil them in my copy of
> > >> the Y2K.
> > >>
> > >> Craig
> > >>
> > >> -----Original Message-----
> > >> From: Jacques Fortin <jacques.f at videotron.ca>
> > >> Sent: Monday, January 14, 2019 8:55 AM
> > >> To: hamfish at comcast.net; 'Larry H' <larry41gm at gmail.com>; 'R-390
> Forum'
> > >> <r-390 at mailman.qth.net>
> > >> Subject: RE: [R-390] R-390A IF deck caps in T501 or T502
> > >>
> > >> Hi Craig,
> > >>
> > >> Make more sense like that !
> > >> So 201G03 = 200pF, 2%, 300VW !
> > >>
> > >> 73, Jacques, VE2JFE
> > >>
> > >> -----Message d'origine-----
> > >> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De
> > >> la part de hamfish at comcast.net Envoyé : 14 janvier 2019 11:52 À :
> > >> 'Jacques Fortin' <jacques.f at videotron.ca>; 'Larry H'
> > >> <larry41gm at gmail.com>; 'R-390 Forum' <r-390 at mailman.qth.net> Objet :
> > Re:
> > >> [R-390] R-390A IF deck caps in T501 or T502
> > >>
> > >> Jacques,
> > >>
> > >> Sorry for the typo.  The bottom line does read 201G03.
> > >>
> > >> Craig
> > >>
> > >> -----Original Message-----
> > >> From: Jacques Fortin <jacques.f at videotron.ca>
> > >> Sent: Monday, January 14, 2019 8:47 AM
> > >> To: hamfish at comcast.net; 'Larry H' <larry41gm at gmail.com>; 'R-390
> Forum'
> > >> <r-390 at mailman.qth.net>
> > >> Subject: RE: [R-390] R-390A IF deck caps in T501 or T502
> > >>
> > >> Craig,
> > >>
> > >> When you wrote 210G03, would you mean 201G03 ??
> > >>
> > >> 73, Jacques, VE2JFE
> > >>
> > >> -----Message d'origine-----
> > >> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De
> > >> la part de hamfish at comcast.net Envoyé : 14 janvier 2019 11:19 À :
> > 'Larry H'
> > >> <larry41gm at gmail.com>; 'R-390 Forum' <r-390 at mailman.qth.net> Objet :
> > Re:
> > >> [R-390] R-390A IF deck caps in T501 or T502
> > >>
> > >> Larry,
> > >>
> > >> I have one of those Amelco R390/A's. Believe it was little used and
> > >> original modules. Serial No. on the IF module is 2062. T501 & T502
> > >> appear to be identical. Starting from top to bottom: a pair of
> > >> dogbone caps, the two windings, two resistors, and the two mica caps
> > >> on the bottom. Tight space and hard to read, but I see CM115E on the
> > >> top of the mica caps and 210G03 on the bottom. There is some color
> > >> coding on the back, dots. No way to see all the dots unless removing
> > the caps.
> > >>
> > >> Hope this helps,
> > >> Craig
> > >>
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