Motorola R100 440Mhz VCO Mods Needed

[Thom]

I have an R100 repeater, Model Q2932A which is currently on GMRS service, (462.55/467.55). It works great there, but will not re-program down to 448.925/443.925 where I need it.

I have tried tweaking the Tx VCO but can't get it to stay locked much lower than about 454Mhz. Wonder if anyone can shed any light on wheather this is possible, and if so, what mods need to be done?

Thanks in advance,

Thom

[Scruffy]

You will need to modify your software to reprogram the repeater first. The VCO steering is a little touchy but not impossible. I have 3 of these running 443TX 448RX with basic alignment after reprogramming.

[Will]

I have found some mods for both the RX and TX VCO's in the R100. Monitor the stearing line "SL" and tweeking the variable cap to put it back in range on the original GMRS freq. Then try adding a ferrite slug to the VCO coil, to get it down to 440 range. They usally have wax or glue in the coil form. Use a small drill bit to remove the glue. My best advice is to remove the variable capacitor and use a 4 to 10 pf fixed mica chip cap to put it back at the same "SL" voltage, without the slug, on the GMRS freq. Note some R100's have a brass slug in the VCO coil(s).
The variable capacitor(s) are a source of a lot of VCO noise and microphonics.

[Search]

Will,
Can you email me direct about the repeater cable for the m100's?

Thanks,
Chris
CLarrick@safety1.net