On 01/08/2012 04:46 PM, Lee K7TJR wrote:
Paul you might want to be careful just shorting the
receiver input. This would also put a short on the
output of your preamp. This would have the preamp
blasted with RF from your TX while trying to feed a
short. My guess would be you could
Why not use a DPDT relay as a bypass... This would allow the antenna
side to be shorted to ground and the preamp input to be terminated into
50 or 75 ohms via a resistor, or in the other position the preamp
would be connected to the antenna. Essentially the relay would be wired
the same way as an
N1BUG wrote:
oscillate. The 25+ dB gain, very low noise figure VHF/UHF preamps I
am more used to can get pretty squirrelly with something other than
50 ohms on the input.
73,
Paul N1BUG
On low bands, I routinely put a small (IE 10 pF) capacitor across
the input of RF gain blocks to kill
Prompted by Roger, N1RJ, I decided to do some digging around. Aided
by isolating specific stages of my receive signal path as much as
possible, and using precision 3 and 6 dB pads at various points to
see where they dropped the IMD more than the attenuation of the
pad(s), I have come up with a
Of N1BUG
Sent: Sunday, January 08, 2012 11:46 AM
To: Topband
Subject: Topband: BCI chase update
Prompted by Roger, N1RJ, I decided to do some digging around. Aided
by isolating specific stages of my receive signal path as much as
possible, and using precision 3 and 6 dB pads at various points to
see
Paul you might want to be careful just shorting the
receiver input. This would also put a short on the
output of your preamp. This would have the preamp
blasted with RF from your TX while trying to feed a
short. My guess would be you could destroy
preamps doing this.
Lee K7TJR OR
Paul, I will agree with Lee. I think the best would be to use a small relay
that would open the antenna on transmit and also short it to GND. Nothing
touching the Pre-Amp.
All Electronics have some very nice DIP relays that will do the job. I have
no connection with All Electronics, Just a good
