[R-390] C553 replacement?

Sun Feb 26 18:04:18 EST 2023

Sprague type 96P is a Vitamin Q impregnated hermetic paper cap rated for 125C operation.  In the 1972 United Technical Publications “Master” 37th edition, Section 1500, source page 212, Sprague advertises that they exceed MIL-C-25A, the military specification for style CPxx.

Dave

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows

From: Jim Whartenby via R-390<mailto:r-390 at mailman.qth.net>
Sent: Sunday, February 26, 2023 1:32 PM
To: r-390 at mailman.qth.net<mailto:r-390 at mailman.qth.net>
Subject: Re: [R-390] C553 replacement?

Dave
I can verify that C606 in TM 11-5820-357-35P is listed as type CP10A1EE224M as stated but the Collins Preliminary R-390 Manual on page 186 does list C608 as 0.22uF, +/- 20% at 100vdcw and gives a Sprague P/N, 96P22403S13.  Perhaps a misprint by Collins that was caught when the official military manuals were issued?

Regards,
Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy

-----Original Message-----
From: David Wise <d44617665 at hotmail.com>
To: Barry <n4buq at knology.net>; Jim Whartenby <old_radio at aol.com>
Cc: R-390 Mailing List <r-390 at mailman.qth.net>
Sent: Sun, Feb 26, 2023 2:15 pm
Subject: RE: C553 replacement?

#yiv7570053998 filtered {}#yiv7570053998 filtered {}#yiv7570053998 p.yiv7570053998MsoNormal, #yiv7570053998 li.yiv7570053998MsoNormal, #yiv7570053998 div.yiv7570053998MsoNormal {margin:0in;font-size:11.0pt;font-family:sans-serif;}#yiv7570053998 a:link, #yiv7570053998 span.yiv7570053998MsoHyperlink {color:blue;text-decoration:underline;}#yiv7570053998 .yiv7570053998MsoChpDefault {}#yiv7570053998 filtered {}#yiv7570053998 div.yiv7570053998WordSection1 {}That’s correct, C553 is a coupling cap into the R-390A mechanical filter.  It’s a catastrophe if it shorts.  Many people replace it even though it’s a Vitamin Q which should still be good.  I kept the old cap and inserted a current limiter, using a Supertex (now Microchip) LND-150 depletion-mode MOSFET.  Just connect drain upstream, and source & gate downstream, and voila, 1mA limit.   In the R-390, C606 sees 1/19th of 180V so it will last forever.  C608 sees about 180-10+5 or 175V.  If it leaks, the regulator will throttle down.  If you suspect this, measure voltage across 6BH6 grid resistor R624; it should be zero.  Slight leakage is worse than severe leakage, because the 6080’s will overheat.   On pdf page 10 of 34 of TM 11-5820-357-35P, C608 is listed as type CP10A1EE224M.  CP is hermetically-sealed paper.  In specification MIL-C-25D, the second E indicates 400 volts.   Dave WiseSWL (Inactive)   Sent from Mail for Windows   From: Barry
Sent: Saturday, February 25, 2023 8:08 PM
To: Jim Whartenby
Cc: R-390 Mailing List
Subject: Re: [R-390] C553 replacement?   I think C553 is only in the R390A.

Thanks,
Barry - N4BUQ

----- Original Message -----
> From: "R-390 Mailing List" <r-390 at mailman.qth.net>
> To: "R-390 Mailing List" <r-390 at mailman.qth.net>
> Sent: Saturday, February 25, 2023 10:03:27 PM
> Subject: Re: [R-390] C553 replacement?

> A quick look at the R-390 Collins preliminary manual indicates that C-606 and
> C-608 are both rated at 100 vdcw.  Curious that C-608 has 174 volts across it
> according to the voltage table for V-607.
>
> I did not find C553, which tube is associated with it?
>
> Regards,
> Jim
>
> Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy
>
> -----Original Message-----
> From: Barry <n4buq at knology.net>
> To: John Wendler <wendlerjrv at gmail.com>
> Cc: R-390 Mailing List <r-390 at mailman.qth.net>
> Sent: Sat, Feb 25, 2023 8:52 pm
> Subject: Re: [R-390] C553 replacement?
>
> If I'm not mistaken, Dave Medley (and others) suggest that 180v regulator issues
> in the R390 might be due to leakage in C606 and/or C608 and I think those are
> typically Vitamin Q capacitors.
>
> Thanks,
> Barry - N4BUQ
>
> ----- Original Message -----
>> From: "John Wendler" <wendlerjrv at gmail.com>
>> To: "R-390 Mailing List" <r-390 at mailman.qth.net>
>> Sent: Saturday, February 25, 2023 6:01:07 PM
>> Subject: [R-390] C553 replacement?
>
>> The C553 in one of my IF modules is a Sangamo Vitamin Q capacitor, 0.01 uF,
>> 300 V.  It looks good visually and is not a Brown or Black Beauty of
>> Death.
>>
>> What's the group experience with the reliability of the Vitamin Q caps?
>>
>> V/r,
>>
>> JP N5CQU
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