Batboard

I have a R1225 I am currently TX 154.xxx RX 159.xxx the repeater is in uni-directional mode what do I need to change to go both ways? (Don't be a smartass)

Thanks
Steve

The simplistic answer is
1) Go to Radio Wide Configuration and change the operation to bi-directional, and
2) Get a second R1225.

More importantly however, what is it you're trying to accomplish?

Henry

Bi-directional within the same band is going to be difficult; how are you going to filter the antenna?

Hello.

Bi direction duplexers are around, but not a standard off the shelf item, 6 cans in place of the normal 4.
A RICK can be set up to do bi and duplex, sometimes a bit easier.
Most VHF military radios do bi direction retransmit (repeater function).
So, the only thing that will slow you down is the duplexer, correct? wrong!
You can take 2 stock duplexers, use the 3 cans from each, set this up with a combiner and you are all set.
On VHF hi, you will have some big cans, but nothing like the 6 foot cans for lo band.

Thanks for the help, I see where this is heading. $$$

Steve

I don't necessarily agree with Cowthief's engineering (but don't have time to draw out the system and do the calcs, so the point passes), but add another consideration: you will have to relicense your input frequency (159.xxxx) for output and get it re-coordinated.

Hello Steve,

This is not a new idea ... /\/\ has been doing this for 28-30 years with SP requests. I'm not familiar with R1225 repeater but depending if the VHF repeater's receiver frontend bandpass filter is 4 MHz wide and you can software program both the F1 159 and F2 154 MHz on the RCVR and F1 154 and F2 159 MHz on the XMTR frequencies into the code plug. Then with TRC program F1 for 1950 Hz FT and F2 for 1850 FT.

You might need a couple of logic gates (sometimes known as Wild Card functions), at least one to provide a DC Low for the "switch around" PAIR of DPDT RF Coaxial Relays, using double shielded coaxial cable RG-400/U or RG-142/U and either BNC or N Type connectors.

You should also consider to generate a small amount of Delay to Inhibit the repeater's TX from Keying Up as the "switch around relays" pull in or release proventing RF being on the contacts. It also would be very hard on the RF Power Amplifier Stage. Oh yeah, don't forget to put diodes across the DC relay coils to prevent "spikes" being sent down the power leads. I've used a couple different types of duplexers for this application and never experienced any problems.

There will be some additional degradation in RF Power Output and Receiver Sensitivity due to the relays and additional coaxial cables.

Dan

Folks this is not hard or even complex...

1. get rid of the R1225
2. get 2 GM/SM/1225 mobiles
3. program each simplex for 1 of the repeater frequencies
4. connect rx audio to mic input (2X)
5. connect cos to PTT (2x)
6. connect to duplexer... no fancy cans or other peripherals needed

...Z

oops dbl post