[TenTec] Replacment cw filter

[Mike Hyder -N4NT-]

I didn't know about Dan's but they have an audio CW filter kit:

http://www.danscloseoutsandspecialdeals.com/kitcloseouts.html

http://www.danssmallpartsandkits.net/

----- Original Message ----- 
From: "Mike Hyder -N4NT-" <Mike_N4NT at charter.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Tuesday, December 14, 2010 11:09 AM
Subject: Re: [TenTec] Replacment cw filter


> Having used several of the "older" Ten-Tec rigs, my feeling is that 98% of
> the time I am much happier using an audio filter in the rig than a crystal
> filter.  The audio CW filter makes them sound like "real Ten-Tecs" to my
> ears.
>
> If you choose to fabricate an audio filter, it is important to put it into
> the circuit as the rig is originally designed.  The AGC voltage in the 
> rigs
> is generated from audio.  If the filter does not appear before the AGC
> sampling point, signals outside the passband can still "pump-up" the AGC
> voltage.  This is true of external audio filters, too.
>
> 73, Mike N4NT
>
> ----- Original Message ----- 
> From: "Curt" <rhulett1 at consolidated.net>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Cc: "Marty Hartwell" <mhartwe at gmail.com>
> Sent: Tuesday, December 14, 2010 10:37 AM
> Subject: Re: [TenTec] Replacment cw filter
>
>
>> Hello Marty,
>>
>> Having the same problem you did trying to find a 245 for a 544 I bought,
>> used the 245 from my 540 as a pattern.  All the components are still
>> available, so had a PCB fabricated using my 245 as a pattern.  Did a less
>> than perfect job of duplication, had to redrill holes for the 7 vector
>> pins
>> used to connect the board to the rig.
>> A lot of time and trouble for what might just as easily be accomplished
>> using an outboard audio filter, just to prove to myself that could do it.
>>
>> Anyway, it works perfectly, just same as the 245 in my 540.  It isn't 
>> very
>> complex, just two dual op-amps and some resistors and caps.  Somewhere I
>> have the TT documentation, pictures, parts list, schematic, pattern of 
>> the
>> PCB.
>>
>> Building one on vector board is certainly feasible, and maybe easier than
>> dealing with a PCB.
>>
>> GL & 73, Curt
>
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