[TenTec] 291 Tuner now works fine.

Maurice P. Haynes k4beh@juno.com
Mon, 09 Mar 1998 19:28:49 EST

To: Paul Clinton -Service Manager

Paul, many thanks for locating and installing the "white" inductor in the
291 tuner that A.T. brought to you from me.  Since I got it back the
problem is gone and it now works just as well as the other one I have
with the same "white" inductor.  

I still believe that the black material in the plastic is probably
conductive at RF frequencies.  Maybe it has "lampblack" (carbon) in it. 
I would try taking the unassembled black halves and place them in a
microwave oven for a few minutes.  If they are indeed RF insulators they
will remain cool; if they heat up, you're in trouble!  I only know that I
have had three that have failed at as low as 15 watts (SCOUT in tune
mode) and two white ones that work fine at 100 watts (PARAGON and DELTA
II output).  All other conditions the same.  They have failed when tuning
a 52 ohm coaxial fed dipole cut to frequency with no balun in the circuit
as well as a 135' dipole fed with ladderline thru a 4:1 balun.  The
common denominator is the black insulator.

Thanks again for the fine repair job and quick turn-around, as usual. 
Tell Garry Green howdy.


Pat - K4BEH

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