[TenTec] 1320 T-Kit

[Wj5mh@aol.com]

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