SB-104A cw filter

[JF]

Jerry W9CTB wrote:
>  Can someone please give me the Heath part # for the sb-104a
 >  cw filter.
>  Tnx/73     Jerry...W9CTB


I believe it's 404-548, center frequency 3395.7 kHz, impedance 2K.
There's one for sale on eBay, item 130072368915.

However, that's just the crystal filter itself, not the complete
installation kit.  If you are thinking of just plugging this filter
into the SB-104A board E, that will not work - the factory kit
consisted of the filter plus a whole bunch of resistors, diodes and
toroid coils. The 104A schematic shows some of the values, but not all,
so if you don't already have them it would be best if you could find a
copy of the original cw filter kit manual. There might be a manual at
Vintage Manuals,   http://www.w7fg.com/
        manual #SBA-104-3, Heathkit CW Manual,  for $10.

Here are some of the CW filter values missing from the SB104A board E
schematic that I was given by
       http://www.qsl.net/k5bcq/sb104/sb104.html

   L676 & 677 = 36.5 uh,   L678 = 100 uh   L679 = 180 uh
   Small caps are silver mica, diodes are 1N458 or 1N914

If you don't have them, you might wind your own toroids with cores
from AMIDON,        http://www.amidoncorp.com

For another 400 Hz CW filter for Heathkits, you might check out
International Radio at    http://www.qth.com/inrad/
       (click on FILTERS then HEATH)
They list their 2702L 400 Hz CW filter for all Heath HF rigs for $105,
but that may be just the crystal filter, not a duplicate of the whole
Heathkit CW filter kit. You'd have to write them to ask.

73   John   KE5ZB

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