LTR repeater on two non-LTR radios

[wireless.friendly]

Hi all!

It is possible to build LTR repeater on two non-LTR radios, for e.g. on trunked Maxtracs (D35 or D45) or trunked Maxtracs converted to conventional radios (like described here http://www.batlabs.com/maxrad.html)?

I remember that non-LTR radios must be modified. I am not sure, but something related with AF filtering - frequencies about/below 300 Hz. But I am not sure & can be wrong about it!

Any help will appreciate.

[Wowbagger]

I assume you have an LTR controller - otherwise you are dead in the water.

LTR signaling is low-frequency - below 300 Hz. Most radios will NOT accept that low a frequency on the mic input, nor will they output that frequency on the speaker. You will have to be able to a) get an audio tap right at the discriminator output on the receive side and b) inject the LTR datastream after any bandpass/highpass filtering on the input to the transmitter.

[wireless.friendly]

Wowbagger

I have controller, yes.

And my Maxtracs with 16 pins connector. It has pins # 5 (Flast TX audio) and # 11 (RX audio).



Anydoby know, pin # 11 (RX audio) has filtered or flat audio output?

[Wowbagger]

Wowbagger

I have controller, yes.

And my Maxtracs with 16 pins connector. It has pins # 5 (Flat TX audio) and # 11 (RX audio).



Anydoby know, pin # 11 (RX audio) has filtered or flat audio output?

I learned a long time ago "Sometimes it's the questions you DON'T ask."

OK, so I'd say that you'd want to drive pin 5, "Flat TX audio" with the trunking data, and pull the data from pin 11, "RX Audio"

If you have an audio spectrum analyzer, do this: set up the radios to listen to each other - i.e. one Maxtrac receiving the other. Drive one radio with the sweep generator output of the audio analyzer, and look at the RX audio from the other radio. Pay especial attention to the 20 to 300 Hz region - it should be flat, and ideally at the same level as the 300 to 4kHz region.

If you cannot tune the radios to receive each other, you need a known good transmitter and known good receiver - for example, a service monitor.

On the extremely unlikely chance you know somebody with a 2975, you could do this directly (assuming they have the audio analyzer option).

[wireless.friendly]

Thanks, but does not have analyser.

May be anybody know which audio response has Maxtrac on 5 & 11 pins? Flat (in 20..300 Hz range) or filtered (by low-cut filter)?

[wavetar]

It should work for you...the same pins are used for LTR hook-up in the GR1225 series repeaters. No guarantee they'll react exactly the same, but I believe it'll be ok.

Todd

[wireless.friendly]

Thanks for info!