ARRL September VHF Contest - 2022
Call: N8RA
Operator(s): N8RA
Station: N8RA
Class: Single Op-All Modes LP
QTH: FN31
Operating Time (hrs): GOK
Summary:
Band QSOs Mults
-------------------
6:
2:
222: 11 9
432: 17 11
903:
1.2:
2.3:
3.4:
5.7:
10G:
24G:
-------------------
Total: 28 20 Total Score = 1,120
Club: Yankee Clipper Contest Club
Comments:
The contest weekend presented a good opportunity to test a recent modification
to my Elecraft XV432 transverter.
In the last contest I noticed that its frequency stability was not sufficient
for dependable FT-8 operation. As it went thru transmit cycles, the received
signals on the waterfall would slowly arc over on a curved trajectory. It took
about 15 minutes of operation to settle down
I theorized that the high FT-8 duty cycle raised its internal temperature faster
than its local oscillator crystal oven could compensate. The little fan inside
simply spread the heat from the PA around to the whole unit.
In a separate box I rigged a freq synthesizer (from Q5, having a nice TCXO) set
to produce the required LO frequency. The LO in the transverter was disabled
with a jumper from its transistor’s base to ground. A BNC connector added to
the side of the transverter near the internal LO circuit allowed for a small
capacitor to then couple in the synthesized signal, and LO levels and alinement
were similar to the original.
It worked well! Now I get quick answers to my transmissions. And, it is
interesting to watch other’s signals on the waterfall- some are obviously
stable with a vertical series of transmissions, but others have curving
trajectories, often seen when they would first start up on the band, and those
stations were often difficult or impossible to contact as their frequency moved.
My XV144 and XV222 transverters do not seem to suffer the same problem but will
get a closer look.
Chet, N8RA
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