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[TenTec] Beginner Corsair II Questions

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Subject: [TenTec] Beginner Corsair II Questions
From: chestert@pressroom.com (Chester Alderman)
Date: Sat, 13 Sep 1997 23:19:19 -0400
Peter...no, you dont have a problem. The Corsair II and older TenTec rigs have 
an awful sidetone. It is generated by a UniJunction Transistor (UJT) and the 
'tone' created is close to a square wave, which is why it sounds so horrible. I 
have been able to 'fix' that by removing one of the resistors in the resistive 
'pad' between the UJT and the op amp, and adding a simple audio filter in that 
resistors place. Of course a square wave is the fundamental oscillating 
frequency and ALL of it's harmonics. By running a square wave through an audio 
filter, at the oscillators fundamental frequency, you can eliminate most of the 
harmonics; what comes out of the audio filter is a much cleaner and much better 
sounding sidetone.

At 05:14 PM 9/13/97 +0100, you wrote:

>>you must very carefully get

>>the CW xtal filter to center at 750 Hz also, by centering

>>the PBT at the top and making sure the beat note is right

>>(you can check by comparing it with the sidetone I think).


>The sidetone on my Corsair II (which I've had for a few months now -

>it's my first TT rig, and one with which I am delighted) is *not* a

>particularly clean tone.  I would find it hard to match the pitch of 

>an incoming signal to it.


>Does this mean my rig has a problem (with the sidetone), or is this

>simply 'how it is'? 


>PS Don't forget, the sidetone pitch is variable, and therefore may not

>be adjusted close to 750Hz.


>72/73, Peter G3XJS ( http://www.barville.demon.co.uk/qrpinfo.htm )



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Chester Alderman

<color><param>0000,0000,ffff</param>W4BQF -- Tom



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