[Kenwood] TS-2000X Final Driver Problems

[manualman at juno.com]

East Coast has the 2SC1972 listed as available. Put in the Part Number
Field 2SC1972. They want $85 for each one.

Pete, wa2cwa
www.manualman.com


On Sat, 05 Jul 2014 09:16:58 -0400 "Roger Shultz" <nj2r at verizon.net>
writes:
> A friend got all excited to work the VHF contest 2 weeks ago and 
> found he
> had no output on 2 meters nor 6 meters. He gave up disappointed but 
> asked me
> if I could look at his radio to see what was wrong. He had contacted 
> Kenwood
> who said it was probably a driver.
> 
> I've checked it out and indeed it seems to be the Q3 and Q4 
> 2SC1972's that
> are bad but a few other things don't seem right too.
> 
> The DC voltages are correct on Q2, the 2SC1971 but the RF levels are 
> much
> higher than expected.
> 
> Base is about right at 600 mv though spec'd at 450 mv, Collector is 
> 8 volts
> p-p spec'd at only 2.5 volts p-p WHY?
> 
> On the bases of Q3/Q4 I see 2 volts, spec'd at 1.4 volts p-p and 
> Collector
> 150 mv spec'd as 6 volts p-p.
> 
> Now the DC readings for Q3/Q4 are supposed to be 0 in receive and 
> .74 vdc in
> transmit but I have 3.1 volts dc in both conditions. Collector 
> voltage is
> correct at 13.8 vdc.
> 
> I see a couple other questionable parts as well. D2, a thermistor 
> seems to
> be shorted. Someone replace F1 with a "hay bailed" glass fuse with 
> leads.
> 
> Presumably that someone had replaced Q2 before and was none too neat 
> about
> it so what else may be wrong is a mystery.
> 
> I have not had much luck locating 2SC1972-26's yet at either 
> PacParts or
> East Coast Transistor or the usual suppliers. Any thoughts other 
> than eBay
> China?
> 
> Thanks in advance for your thoughts on the above.
> 
> 73, Roger, NJ2R