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RE: [TenTec] MOD: Corsair Sinewave Sidetone

To: <tentec@contesting.com>
Subject: RE: [TenTec] MOD: Corsair Sinewave Sidetone
From: "Paul - W8KC" <w8kc@comcast.net>
Reply-to: tentec@contesting.com
Date: Sun, 17 Oct 2004 09:29:43 -0400
List-post: <mailto:tentec@contesting.com>
Great.  I already created the webpage so give me a couple of pics to pretty
it up and we'll be in business.

The new website is  S L O W L Y  coming along...

And you might want to take a sneak peek at the future of yet another TT fan
page...

www.tentec.org   :-)



-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Steve N4LQ
Sent: Sunday, October 17, 2004 9:09 AM
To: tentec@contesting.com
Subject: Re: [TenTec] MOD: Corsair Sinewave Sidetone

Certainly Paul. I got this one for $50. It was tired and dirty but looks 
pretty nice now. I can take a photo of the jack 28 area and send it to you 
shortly.

Steve N4LQ
----- Original Message ----- 
From: "Paul - W8KC" <w8kc@comcast.net>
To: <tentec@contesting.com>
Sent: Sunday, October 17, 2004 9:04 AM
Subject: RE: [TenTec] MOD: Corsair Sinewave Sidetone


> Steve,
>
> With your permission I'd like to add this to the information on the W8KC
> Virtual Ten-Tec Museum.
>
> Do you have any photos?  I sold my Corsair to finance the Omni VI.
>
> 73! =paul= W8KC
> Collector of Ten*Tecs and other fine plastics.
> Visit the Virtual Ten*Tec Museum at http://mywebpages.comcast.net/w8kc
> Listen to 7.040 MHz from anywhere with Media Player v9
> http://www.w8kc.com/stream.asx
>
>
>
> -----Original Message-----
> From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
> On Behalf Of Steve N4LQ
> Sent: Sunday, October 17, 2004 1:01 AM
> To: tentec@contesting.com
> Subject: [TenTec] MOD: Corsair Sinewave Sidetone
>
> TenTec Corsair sinewave sidetone modification:
>
> The sidetone in the Corsair produces a sawtooth wave, rich in harmonics 
> and
> is unpleasant to listen to for most of us. Fortunately, there is a very 
> easy
> solution.
> The Corsair has two audio oscillators. One is the sidetone, activated when
> you close the key and the other is the spot feature, activated by pushing
> the spot button. Push the spot button and notice how pure it sounds. This 
> is
> a sine wave oscillator. We are going to use this for our cw sidetone.
> The process is very simple:
> 1. Turn the Corsair over. Remove the Corsair's bottom cover.
> 2. With the Corsair's front panel facing you, locate the IF/AF board. It 
> is
> on the right, front side of the rig.
> 3. Locate connector 28. It is located on the left, front side of the IF/AF
> board.
> 4. Using a piece of wire, short the two outer pins of connector 28 
> together.
> I pulled the connector off, stuck the fine wire inside each outer hole and
> plugged it back in taking care not to allow the jumper to contact the 
> center
> pin. This could be done from the top of the plug. It's you're preference.
> 5. Turn the volume down completely on the original sidetone.
> 6. Key the rig and adjust R2 for proper pitch and R3 for desired volume.
>
> Further refinements:
> 1. To clean up some of the audio thumps, solder a .22uf (224) capacitor
> between the center wiper of R2 and ground. I obtained ground from the lug 
> on
> the PTO.
> 2. The original sidetone will leak some of it's nasty tone even when 
> turned
> down to minimum. I grounded the front end of R4 which totally kills the
> beast. Use the PTO lug for ground. There are other solutions but this one 
> is
> easily undone.
>
> Side effects:
> The sidetone will now sound very clean. Adjusting the pitch and volume 
> will
> not be as easy unless you knock out a hole in the chassis under R2 and R3.
> Pushing the spot button will still produce the tone but it will be 
> slightly
> different from the sidetone's pitch. This could be compensated for very
> easily by installing a trimmer pot in series with the spot button however 
> I
> seldom have need for the spot button and the difference is very slight.
>
> Corsair II.
> The Corsair II's spot button functions totally differently. Instead of
> keying another oscillator, it changes the frequency of the BFO. So from 
> what
> I can tell by the schematic this mod will only work with the older 
> Corsair.
>
> Note: When I aligned the BFO oscillators, I set the offset for 600hz 
> instead
> of the factory 750hz because I prefer the lower pitch. To adjust the new
> sidetone, you can connect a frequency counter to the speaker and adjust 
> for
> 600hz a pitch. This is strictly user preference.
> Note 2. Using an MFJ-281 ClearTone speaker will produce beautiful cw and
> reatly reduce some of the anoying thumps associated with the Corsair's agc
> and qsk system.
>
> 73
>
> Steve Ellington N4LQ
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