[TenTec] 1320 T-Kit

[n4lq@iglou.com]

Did you happen to notice how you can also tune the radio by moving the 
speaker up and down? I removed my speaker and use an external MFJ 
ClearTone. That huge magnet directly over the vfo coil really has an 
effect! 

-----Original Message-----
From: Wj5mh@aol.com
To: tentec@contesting.com
Date: Wed, 17 Apr 2002 08:55:28 EDT
Subject: Re: [TenTec] 1320 T-Kit

> Been doing a little more troubleshooting on the 1320 looking for the
> source 
> of drift after a couple minutes of transmitting…  I removed the cover
> and let 
> the radio stabilize for several hours.  After heating the tip of a 
> nonconductive probe with a hairdryer, I touched various components in
> the VFO 
> circuit, and found that oscillator Q2 (2N4124) is VERY sensitive to
> heat.  
> Holding the probe to the side of the transistor will cause immediate
> downward 
> drift.
> 
> Varactor D1 (MV209) will also cause downward drift, but is slow to
> react to 
> the temperature change.  (Inserting the probe near some components
> without 
> heating it does cause some change in frequency, but no drift.  I took
> that 
> into consideration when performing these heat tests.)
> 
> Touching various capacitors in the circuit causes some upward drift,
> but the 
> reaction time, to me, doesn't even approach Q2's.  Personally, I don't
> see 
> any way the capacitors can react quickly enough to offset any negative
> freq 
> drift caused by Q2.
> 
> Note:  I turned the fan on when I sat down to write this e-mail, and
> listened 
> to the VFO freq change.  It stabilized after moving 165 Hz.
> 
> Question…  Is it normal for a transistor to be this sensitive to
> heat?
> 
> Thanks for help…and patience.  (Solder connections in the VFO, buffer
> and amp 
> stages have been re-soldered.)
> 
> 73,
> Joe ( WJ5MH )
> Wj5mh@aol.com
> 
> 
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