[GreenKeys] CV-2460 Converter update

[W2HX]

Hi all,

I've been working diligently getting my RATT/RTTY set up and continue to try to improve my set up. I've been using this CV-2460 military ratt converter. It has only 850 shift (technically it has another, useless shift) and loop connection. One of the features is supposed to be an automatic switch over from receive mode to transmit (mark-hold) mode when it ceases to hear a mark signal. This never worked for me so the printer would be printing garbage from the noise between station transmissions. Only once a mark carrier was received it would stop printing junk.

With some wisdom from Dan K6YIC about these converter units, I believe I now have it working very well.  The adjustment is primarily reducing the audio input level, which is adjustable within the CV-2460. But how to adjust it? Luckily, I had recorded the audio from the 1-28-2023 9AM RATT net session to an mp3 file. I routed the audio from my computer to the CV-2460. But since I was working with audio levels, I had to make sure the computer audio output was "normalized" such that it would emulate the audio output of my receiver. All audio in the shack is normalized to 0 dBm into 600 ohms. I have a panel meter that I can route any audio to to set the levels.

I set the PC output to 0 dBm so that I can emulate the audio output of my receiver, the Harris RF-590. The audio that I recorded off-the-air and is about 1 hour and includes strong and weak stations and importantly, dead air between station transmission. With the PC audio routed to the CV, I was able to adjust the audio level on the CV from not decoding anything to juuuust where it would begin decoding the audio. Then I played around with the audio "BIAS" setting to get the best results. I would start and stop the audio for about 15 seconds on either side of a station turn over, going back through the station turn over and over while adjusting the pots.  Since I use AGC on the receiver, weaker stations will be boosted to the extent possible and strong stations will be attenuated all to provide 0 dBm audio.

I am pleased to say that I have it working very well now. Maybe three characters of garbage print when a station goes off the air before it switches to mark-hold. I can't wait to try it. I might not be able to make next Saturday's RATT net but hopefully soon.

73 Eugene W2HX
Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos

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