[R-390] Carrier Level Meter Issues

[hamfish at comcast.net]

I'm getting old & lazy, maybe I should spend time and locate the manual for my Sprague TO-6A. Here goes.................

Seems to me electrolytics are tested for leakage. Paper/foil, film, etc caps are tested for insulation resistance. Good luck with silver mica caps???????????

Insulation resistance is the method I used for C551. The Sprague is the only cap analyzer which I own and don't have experience with the HeathKit. 

Regards,
Craig

-----Original Message-----
From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On Behalf Of Jordan Arndt
Sent: Sunday, March 6, 2022 4:25 AM
To: gary.biasini at shaw.ca; 'Larry H' <larry41gm at gmail.com>
Cc: 'R-390 Forum' <R-390 at mailman.qth.net>
Subject: Re: [R-390] Carrier Level Meter Issues

Hi again group...

Any leakage of C551 will dramatically alter the AGC characteristics, with the results of leakage being seen as a longer to much longer AGC recovery time and a lower and "softer" AGC voltage.

I rebuilt C551 in my three 390As using non-polarized 1.5uF @ 450Vdc film caps which just fit inside the original square can. The result is a "stiffer" AGC voltage, and a noticeably quicker return to receive than with a 2uF cap.

I use a restored Sprague TO-6 to detect leakage, and these film caps show no measurable leakage at all, where all of the original C551 caps clearly showed varying degrees of leakage. I'd expect that most, if not all, of the original C551 caps are leaky by now and should be replaced/rebuilt...

73...Jordan VE6ZT

----- Original Message -----
From: <gary.biasini at shaw.ca>
To: "'Larry H'" <larry41gm at gmail.com>
Cc: "'R-390 Forum'" <R-390 at mailman.qth.net>
Sent: Saturday, March 05, 2022 10:13 PM
Subject: Re: [R-390] Carrier Level Meter Issues


> Larry,
>
>
>
> Thanks. In fact, I started on one tonight which will be the subject of a 
> separate post once I do a bit more work.
>
>
>
> I checked the manual for the IT-11 and in fact, when properly calibrated, 
> on the setting for “Paper, Mica, etc.” capacitors – i.e. anything other 
> than Electrolytic or Mini-Electrolytic capacitors, the eye will not open 
> if the leakage is more than 2 ua so, the C551 that I tested leaks less 
> than 2ua.
>
>
>
> By the way, the threshold for Mini-‘lytics is 15ua and the threshold for 
> Electrolytics is the 2ma.
>
>
>
> Thanks again for your response. 

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