Hi, All
A couple of recent threads here on "Amps" started me thinking about
RF shielding and RF affecting solid-
state relays. My question is kind of long, so please bear with me.
I recently completed my long-delayed rebuild/mods of a Drake L7. The
P/S was completely rebuilt into a
new larger enclosure with its own off-delayed cooling fan and
soft-starts on both the H.V. and filament
transformer primary. The power switch in the amp now only turns on a
few relays and timers instead of the
whole H.V. PS! In the amp, I've added an electronic cathode bias
switch, QSK vacuum relays for T/R
switching, and a transistor switch to make the keying line compatible
with the whimpy amp-keying
transistors and/or relays used in today's transceivers. Also added
off-delay to the amp's internal cooling
fan, and disabled the SSB/CW rocker switch so the amp always runs on
the higher plate voltage.
Both the ECBS and the new transistor switch are mounted on the right
hand (facing the front panel) wall of
the RF deck. The circuit boards I made for these two items are a
little "roomy" so there wasn't enough
room to squeeze them in underneath the chassis, behind the power
switch (That's where the vacuum relay
PS is). Though technically within the RF deck enclosure, these two
boards are more than 2 inches away
from any of the tank components.
I've tested the amp for tune-up and power out on all bands except the
WARC bands. Bias has been
adjusted for proper idling current and T/R change-over works beautifully.
Now (finally) my question: After reading the discussion on
solid-state relays used in the PS's of amps and
their possible problems with RF, am I likely to have problems "down
the road" due to the placement of
these circuit boards? Or, is this a case of "if you haven't had any
problems with it by now, it's OK?"
BTW, the ECBS, vacuum relay controls and transistor switch are all
Rich Measures' circuits, which I have
used very successfully and without failure in several other amps.
Anyone have similar good/bad experiences with T/R circuits in the RF deck?
73,
Charles - K5ZK
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