Gang,
This relates to the ANC-4 noise cancelling (phasing) device by JPS which a
number of us have found to be indispensible in high noise locales. See posts
earlier this week for how to buy one or find the Davis RF ad in QST.
Here are the mods I have received directly from Tom Jacks, P.E. K4ICJ at JPS:
1. To increase sensitivity of the T/R circuit to respond to lower powered
QRP rigs (not needed for rigs running >3w) Tom says:
"Increasing sensitivity is quite easy to do, Preston. In the pad located
close to the two SO239 connectors, locate R18 and R31 (both 3k). Change both
of these to 10k and your problem should be solved."
2. To set up the ANC-4 to switch T/R directly from a keyline Tom advises:
"It's not all that hard to do and we may do it ourselves in time if we elect
to modify the ANC-4. First, set the Decal jumper to "Fast". Then connect a
1N4004 diode anode (arrow head) to the top (closest to the rear) of R29 and
take the cathode (bar) through a wire externally to your keyline. That's all
there is to it. Good luck. 73, Tom"
That's it gang. Hope it helps. Since I boosted the power out of my Sierra,
I frankly have not needed to try these mods. But I sure saved them for the
future.
72,
Preston WJ2V
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