[AMRadio] Sommerkamp FR100B Receiver

[Bruce]

Hello Mark,

Here is an article on how to repair the Kokusai mechanical filter:

http://jlkolb.cts.com/site/koku.htm

(Click on the photos to enlarge them).

73, Bruce WA8TNC
================
mark depaepe wrote:
> Paul, Thank you for the detailed email about this receiver.   I will have to look into the mechanical filter. When you removed the old foam, did you replace it? The first order of business will be to order a set of tubes and caps, while I am waiting on those itmes I can look into the mechanical filter. Thanks again, 73Mark
>   >  From: w9ac at arrl.net
>> To: amradio at mailman.qth.net
>> Date: Wed, 23 Nov 2011 19:17:20 -0500
>> Subject: Re: [AMRadio] Sommerkamp FR100B Receiver
>>
>> Mark,
>>
>>
>> The FR-100B uses a Kokusai 455 kHz mechanical filter.  If the receiver seems
>> extremely dead, be prepared to completely restore the filter.  It requires
>> disassembly of the filter module and clearing out decomposed foam from the
>> ceramic tuning discs.  The rotted foam forms a mechanical 'short" across the
>> discs.  It's about a three hour job to do it right.  But after cleaning?
>> Wow, what huge difference.  I never would have believed that a ca. 1960s
>> tube Rx would have too much gain and sensitivity on 10m.  This one does when
>> the filter is working properly.
>>
>> Just be aware that the odds are not in your favor of the receiver being
>> functional.  It will be almost imperative to clean the mechanical filter.
>> I've only found perhaps one in ten that was working without significant IF
>> path loss.
>>
>> I think the FR-100B is historically significant.  For better or worse, it
>> was the product that laid the foundation toward the obliteration of U.S.
>> manufacturers.  From the FR-100B came the FR-50, then the FTdx series,
>> FT-101...and the rest is history.
>>
>> Paul, W9AC
>>
>>
>>