TS-870 Taking it in the rear

[aseecobra]

Hey all,

When feeding audio into the rear input:

1. Does the monitor still work?

2. Does VOX still work?

3. Does FM xmit still work?

Thanks

Chris

[ruisgc]

Hi Chris,
Hello and thanks to join us.
Responding to your questions,

1. Does the monitor still work? --- Yes (very well indeed)

2. Does VOX still work? ---------- No (neither the carrier and Mic controls) because those are used with the front mic. Using the back you uses the digital communications port (TNC) Pin 11(Audio +) Pin 12(Audio Ground / Shield), also you will need to do PTT with pin 9 and 12 (footswitch) this will mute the front mic audio input. I also have the pin 8 and 12 connected (Ground).
If you will use this connection is recommended the change of the C131 cap with a 4,7uF for low frequency response to pass.

3. Does FM xmit still work? ------- Yes (all modes still working fine)

Hope I helped you see you around...
Best wishes,
73 - Rui

[Voodoo Guru]

Howdy Chris!!
Welcome to the Forum!!!!
Glad to have ya here.

Thanks Rui, you said it all!!!
Ya'll take care,

[KC8TMV]

I have been using the rear input on the 870 for almost a year now and I am as happy as a hound dog chasn' a possum up a tree, but I can't seem to get the audio level up when trying to use AM. I am guessing this is because you need the mic gain knob to be working to get the carrier modulated (right?, wrong?).

I can use the front mic input, but we all know the magic comes from that magic socket in the back!

Any thoughts from the group?

-Steve

[Voodoo Guru]

Hey Steve,
If memory serves us right, its been awhile since a 870 has been here,
The AM can only be modulated up to about 85%.
Doing this requires more Mic Gain as you know.
Turning up the Level of the audio coming into the rear of the ACC2 connector should equate to the same thing.

Try that and see,
Take Care,

[ECC82]

11(Audio +) Pin 12(Audio Ground / Shield), also you will need to do PTT with pin 9 and 12 (footswitch) this will mute the front mic audio input. I also have the pin 8 and 12 connected (Ground).

Thanks for the info, I was planning on using the back ACC2 on pin 11 (+) and 12 (-) for audio and the front connector just for PTT, but will connect PTT to 9 and 12 on the ACC2 instead. Connected 8 and 12 to each other.

I bought an 870 from 2000 a month ago and was planning to use that rig for ESSB but bought a 870 from 2004 this weekend, so one of the last 870's made, it is in almost new condition very well kept indeed. The C131 mod has been done and I hope to hook up the audio via the ACC2 very shortly.
I'm using a Heil PR781, signal goes in to a tube pre amp, this one:
http://www.ehx.com/products/12ay7-mic-pre
Changed the tubes it came with to European Telefunken.
Hope to achieve a warm tube sound that way, that signal goes into a Symetrix 528E and from there in to the ACC2. Hope this works.

EDIT:
Got it hooked up now and on the monitor/headphones it sounds very good. Very happy, thanks for the information given in replies and info posted on this site.