GP300 UHF Max TX/Rx Tuning Range?

[seleong]

I have a modified UHF GP300 (2 to 16 channel) and wide-band freq. programming. I am curious what the real usable band limits are even though it can program anywhere between 403-512MHz or so. Can tuning be accomplished using normal RSS? Although the radio seems to Tx OK, it seems to be quite deaf outside of it's original tuning range (403-430MHz). Thanks for your help!

[Will]

The receivers RF front end and transmitter filtering will not allow you to go too far beyond these frequencies. There is also the VCO which may not lock beyond the rated range. These radios are very well built within the frequency range limmits.
400 to about 435 would be the max for that radio. The 450 to 470 radio will usally go 442 to 475.

[seleong]

Hello Will!

Thanks very much for your help. I guess I'd rather get a radio tuned to the proper band split. Thanks again for the technical assistance!

Steve KC6IJM

[HAM-AAF]

Many GP300UL/UH/GP88/P110 can work at HAM BAND 430-440MHz, it has about 40-50MHz range for VCO. There is two VCO adjustments on the board, we can adjust it with out software. One is for RX, one is for TX. If you set the frequency far away from the standard frequency, you need adjust the VCO.

[seleong]

Hello! Thanks for your reply! Where are the VCO adjustments located? I don't have a detailed UHF Service Manual for component locations. I can give it a try if I know where the adjustments are located. Thanks again!

Steve KC6IJM

[raymond345]

I hope u have a freq. counter or a
service monitor to keep in operating spec.
This keeps the other radio operators happy.

[HAM-AAF]

they are on the middle left of the board.
they are in metal mantle with eyelet.
L253 is TX VCO
L258 is RX VCO