[Fwd: RE: [Collins] Re: 75S3 Questions]

[Dr. Gerald N. Johnson]

-------- Forwarded Message --------
> From: Roger Shultz <nj2r at earthlink.net>
> To: geraldj at storm.weather.net
> Subject: RE: [Collins] Re: 75S3 Questions
> Date: Tue, 12 Feb 2008 17:19:53 -0500
> 
> 
> Jerry,
> 
>  
> 
> Rather than fooling around trying to re-stuff old filter cap cans…
> 
>  
> 
> You can get an exact replacement twist lock, 3 section new filter cap
> from Antique Electronic Supply. The new one is a 50 uf three section
> cap so it is even better than the original.
> 
>  
> 
> The spec's are as follows:
> 
>  
> 
>                        CAPACITOR, ELECTROLYTIC, 50/50/50 µF @ 250 VDC 
> 
>                                                          C-EC50X3-250 
> 
>         Made in the USA, to the same specs as the Original Mallory, on
>                                         Mallory's original machinery. 
> 
>       * 3 sections - all 50 µF @ 250 VDC 
>       * -10%, + 50% tolerance 
>       * 85° temperature rating 
>       * 1" diameter x 3" tall 
>  
> 
> 
> Their web address is www.tubesandmore.com
> 
>  
> 
> The Price is $30 and well worth it IMHO.
> 
>  
> 
> 73, Roger, NJ2R
> 
> 
> 
>  
> 
>  
> 
> -----Original Message-----
> From: collins-bounces at mailman.qth.net [mailto:collins-
> bounces at mailman.qth.net] On Behalf Of Dr. Gerald N. Johnson
> Sent: Tuesday, February 12, 2008 4:25 PM
> To: collins at mailman.qth.net
> Subject: Re: [Collins] Re: 75S3 Questions
> 
>  
> 
> On Tue, 2008-02-12 at 15:28 -0500, Bill Stewart wrote:
> 
> > Man, what a great response to my questions. Many thanks to all who 
> 
> > responded.
> 
> > 
> 
> > I have shut the receiver down, except for some testing. In
> previously 
> 
> > looking around the rcvr, I did note that there were only five of the
> paper, 
> 
> > tubular capacitors...all Sangamo and I believe either .1 or .05's.
> They will 
> 
> > be replaced. The coupling cap to the grid of the 6BF5 is a disc. I
> think 
> 
> > disc caps usually hold up ok, but will check the 6BF5 grid bias.
> Also, 
> 
> > someone mentioned the bias rectifier being a S/T cube...that's what
> I have. 
> 
> > I will replace it with a 1N4007, same as used for the B+ diodes.
> 
>  
> 
> Mount a two terminal without ground terminal (solder tag) strip in
> place
> 
> of the selenium and mount the new diode on that. There's a strong
> chance
> 
> that will cool both the 6BF6 and the power transformer, though the
> tube
> 
> will alway be fairly hot. Hence the dark spot on the cabinet lid over
> 
> it.
> 
>  
> 
> > It does 
> 
> > have 150vdc B+. I think the fuse-block diode mounting was orig with
> this 
> 
> > rcvr since the mounting nuts have some loc-tite on them.
> 
>  
> 
> Shouldn't have been loc-tite, but a colored lacquer also on the solder
> 
> connections. The inspector put a drop on each inspected and passed
> 
> solder connection.
> 
> > 
> 
> > The B+ 'lytic in my rcvr is a Sprague with twist lock tabs,
> 183-1764-00 (may 
> 
> > be a Collins in-house number).
> 
>  
> 
> That IS the Collins part number. The 183 group was all electrolytic
> 
> capacitors.
> 
>  
> 
> > It is 40/40/40 uf @250vdc. It is about 1 inch 
> 
> > in dia. The ones I found at Surplus Sales was 40/40/20 at 450vdc 1.5
> in. dia 
> 
> > and another was 40 at 350vdc and 40/40 at 300vdc 1 3/8 in. dia. I'm
> not sure 
> 
> > if either of these would fit the chassis slots for the twist tabs.
> Anyone 
> 
> > know for sure. I may try my hand at restuffing first.
> 
>  
> 
> They did come in different mounting diameters and the big ones won't
> 
> stuff into a small hole even with a big hammer.
> 
>  
> 
> > 
> 
> > I did receive the manual on cd today and its the forth edition, 1
> jul 1963. 
> 
> > It's not the exact manual for my rcvr but will do for a while.
> 
>  
> 
> Probably for 3B/C. Won't match your receiver several places. Was hard
> to
> 
> read. I wrote the next edition.
> 
>  
> 
> The right manual should be down loadable from CCA manuals.
> 
>  
> 
> > By the way, 
> 
> > if anyone needs to copy this version of the manual, let me know and
> you can 
> 
> > borrow my cd.
> 
> > 
> 
> > On the S-meter illumination, I noticed the inside of my S-meter is
> black. 
> 
> > The inside of my 30L1 meter is white.
> 
> > 
> 
> > Guess that brings me up to date for now. I have some other questions
> re: hum 
> 
> > and some squealing at close to max volume. These problems may go
> away after 
> 
> > I re-cap so will hold off on these questions.
> 
>  
> 
> Signs the big electrolytics are bad (as are the couple little ones).
> 
> > 
> 
> > Again, many thanks for all the help...it IS a real nice rcvr...73 de
> Bill 
> 
> > K4JYS 
> 
> > 
> 
> > 
> 
>  
> 
> -- 
> 
> 73, Jerry, K0CQ, Technical Advisor to the CRA
> 
> All content copyright Dr. Gerald N. Johnson, electrical engineer
> 
>