maxtrac/radius issue assist plz.

[anautofix]

I have a total of 5 maxtrac/Radius radios. all are UHF all are 32ch all have the 16pin rear conn. All take program in the ham bands. 3 of them show the proper freq. and they will either not go into xmit and be deaf on 446 and 447 range but will work above and below that with no issue. 1 will xmit and receive but sounds off freq. When checked with a freq. counter it shows right on freq. VCO issues?? thx for your help.

[kcbooboo]

There are two VCOs in the radios, one for transmit, one for receive. Both can be adjusted so the radio operates on the lower frequencies, but when you do that, you give up operation at the higher frequencies. In other words, you will have about 25-30 MHz operating range: 450-480 or 440-470 (roughly).

If either VCO is told to go too low or too high, it may exceed its operating range and become unstable. When that happens the microprocessor disables transmit or receive.

It's a simple adjustment; all you need is a good DC voltmeter (digital or high-impedance analog), a dummy load, and some small tuning tools. The service manual will give you the location of the VCO coils but won't tell you what to do with them as Motorola doesn't think you should try to fix something as simple as this out in the field. Their preferred method is to have you replace the RF board.

Bob M.

[anautofix]

sounds easy enough...where can I get the manual or at least instructions on how to set the 2 VCO's?? Thx