Thanks to everyone who replied to my request for a 208 schematic. It turns out
I opened up the 208 box last night, and the only things inside were the
selectivity switch and an empty connector that probably held the guts of the
audio filter! So I really don't need the schematic after all. I have an Autek
filter floating around here somewhere, and I will probably find that and add it
to the 505. It will go between the audio output and my phones, and that will
take care of me just fine.
Jim, W8KGI
________________________________
From: Jon Iza <jon.iza@gmail.com>
Sent: Wednesday, February 26, 2020 10:14 AM
To: TenTec@contesting.com <TenTec@contesting.com>
Subject: Re: [TenTec] Need 509 schematic
Folks,
four years ago there was a discussion on the 208 filter on this list:
http://lists.contesting.com/_tentec/2016-01/msg00036.html
It seems it was very similar to the schematics published on QST Jul
1979 pp. 45-47 by Dave and Doug DeMaw while reviewing the Tentec 544.
I have the manual for the 208A, which includes a Notch filter. The op
amp used was the RC4136 which, unfortunately, does not share the same
pinout as the typical, low noise, FET input quad op amps such as the
TL074.
Be well
jon, ea2sn
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