[R-390] FL101 Rebuild (R390)

[B Riches]

 Here is some info on a Corcom 3E01 line filter that I use in restoring R-390-A Receivers
Loss measurements:
5 Khz        7db10 Khz      13 db
Used hp aud gen - read loss with HP AC VTVM

Used Tek Tracking gen + Spec An for traces.
Way too much time on my hands!
73,
Bill, WA2DVUCape May, NJ    On Saturday, October 22, 2022 at 07:02:24 PM EDT, Barry <n4buq at knology.net> wrote:  
 
 That seems like a good plan to me as well.

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, October 22, 2022 4:51:48 PM
> Subject: Re: [R-390] FL101 Rebuild (R390)

> Barry
> A lot has changed in the 70 years since the R-390 was released for production.
>   I haven't found the transfer curves for the line filter in the R-390 but we do
> know what frequencies the Schurter filter will attenuate.
> 
> Personally, I would mimic the 6 amp version which uses inductors close to what
> you report.  As for the smaller caps, lower leakage current perhaps won't trip
> a GFCI.  Check the attenuation curves for the 6 amp standard version, this is
> how the filter will attenuate line noise in the radio.
> 
> Regards,
> Jim
> Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy
> 
> -----Original Message-----
> From: Barry <n4buq at knology.net>
> To: Jim Whartenby <old_radio at aol.com>
> Cc: R-390 Mailing List <r-390 at mailman.qth.net>
> Sent: Sat, Oct 22, 2022 2:14 pm
> Subject: Re: [R-390] FL101 Rebuild (R390)
> 
> Jim,
> 
> Apparently there some versions have four inductors and some have only two.  I
> suppose it depended on for which radio they were specified.  Interesting that
> those Schurter filters use 2.2nF capacitors which are significantly smaller
> than what I'm measuring from the original filter.
> 
> 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, October 22, 2022 12:49:36 PM
>> Subject: Re: [R-390] FL101 Rebuild (R390)
> 
>> Barry
>> I looked on Mouser's site for AC Line filer, 125-250 VAC 10 amps. here is a link
>> to the datasheet:
>> 
>> https://www.mouser.com/datasheet/2/358/typ_FMW_41-1275852.pdf
>> 
>> IIRC, there are four inductors in FL-101 so just duplicate the values given.
>> 
>> Regards,
>> Jim
>> 
>> Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy
>> 
>> -----Original Message-----
>> From: Barry <n4buq at knology.net>
>> To: R-390 Mailing List <r-390 at mailman.qth.net>
>> Sent: Sat, Oct 22, 2022 11:38 am
>> Subject: [R-390] FL101 Rebuild (R390)
>> 
>> After finding the connection between the input and output for the "A" connection
>> was open in FL101 of my R390, I removed the filter, opened the lid (lots of fun
>> there...), and found the problem.
>> 
>> Along with the ubiquitous wooden blocks and wax, I found that the connections
>> for virtually all the capacitors were bad or going bad.  The caps in mine
>> filter have three connections where the end points are the through connection
>> and there's a center connection that serves as the third connection allowing
>> the capacitor's ground connection.  Each capacitor was housed in its own cute
>> little thick paper box - a rather unique configuration that I'd not seen
>> anywhere else.
>> 
>> I'm not sure what caused it, but the endpoint connections were such that I could
>> simply pull the wires away from the capacitor and the capacitor for the "A"
>> connection was the worse of any of them.  I don't know if those are
>> electrolytic and the electrolyte leaked (doubtful as they aren't really sealed)
>> but something caused quite a bit of dark corrosion which had virtually
>> destroyed the solder connections.
>> 
>> In any case, the inductors are still in great shape and I can rebuild it so a
>> relatively happy ending for this once I get the necessary parts.  Anyone know
>> the proper value to use for those caps?  The filter is stamped with FILTER TYPE
>> 97JX56 and I wonder if those numbers indicate the inductance and capacitance
>> value (e.g. possibly 56pF but that's just a guess).
>> 
>> Thanks,
>> Barry - N4BUQ
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