Astro Spectra data noise in RX audio

[mancow]

This one has me lost.

I have a vhf astro spectra that has some sort of data noise in the RX audio. It's a pulsing noise similar to a trunking control channel that changes a bit when a button or other action is taken. The regular audio is clear and normal sounding but there is this data noise on top of it all. Some channels seem to be a bit better than others for whatever reason.

Also, the noise is absent without an antenna. Once the antenna cable connector is within 1/4 inch of making connection the noise starts up and continues while it's connected.

I tried searching board for a similar instance of this but was unsuccessful.

[akardam]

Does it do this with different antenna/coax configurations? How about a dummy load?

Does it do it on just one frequency, or on many/all frequencies across the operating range of the radio?

[mancow]

I believe my first test was skewed due to not running open squelch. I went thought it again with it set to 0 and it does it across the band (various channels). 155.055 seems clean but most of the rest are affected to a varying degree. I doesn't seem to matter whether there is a dummy load or open coax. It's a pulsing data noise. I have tried swapping out parts all except the RF board and VCO. I don't have another RF board to test.

Also, when I push a button, like the MON the regular BOOP is accompanied by what I can only describe as a brief "phaser" "shooop" sound like something from a sci-fi movie. It's as if there is a secondary bit of audio that is being skewed and laid upon the regular proper audio.

This is phar out.

[Code3]

I have noticed this with some older 1 Meg VOCONs. Swapping them out seems to do the trick for me. I'm going to hazard a guess that you are running a HLN6485E or older.

[mancow]

I can't tell you t hat one since the sticker has been removed. I guess I'll try a different one and see what happens.

[mancow]

You were right. Trying a different vocon board cleared it up.

I wonder what is happening with those boards that is causing it?

I have noticed this with some older 1 Meg VOCONs. Swapping them out seems to do the trick for me. I'm going to hazard a guess that you are running a HLN6485E or older.