|To:||LineOne <[email protected]>|
|Subject:||Re: LF: TX > RX isolation test|
|From:||Andy Talbot <[email protected]>|
|Date:||Mon, 16 Jul 2018 07:24:44 +0100|
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Could the coupling also account for your higher noise level at the original closer spacing? Your main, tuned Tx antenna is picking up large levels then coupling this, 21dB down, into the vertical and swamping its own noise pickup.
I use a short Procomm active antenna (an earlier version of this http://procom.dk/products/520-aac-1 ) located directly under my 7m high Tee , and looking at the output from that on a spectrum analyser there is a definite peak at 137kHz when the big antenna is connected. Removing the Tx coax connection, and thus de-resonating, kills the noise peak.
Incidentally, On Tx with 700 watts (about 10kV on the antenna 7 m above it) the Procomm is so badly overloaded it supplies a horrible almost square wave signal of 6 volts pk-pk. Around +28dBm. Several times I've forgotten to de-power it on transmit and left that input to blast the SDR-IQ which complains loudly by flashing its red overload LED and sending a message to its driver software. But it survives that degree of overlaod
I have blown one of those Procomm antennas over the years - not sure how, I just found it was dead one day. It could have been by overloading on Tx; it could have been another reason.
On 16 July 2018 at 02:20, N1BUG <[email protected]> wrote:
First, the rest of the story on my RX antenna...
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