Range 3 UHF A5 Spectra to 440Mhz

[hfd376]

Hello all, in trying to get the above radio to down to 440 Mhz, I programmed the frequencies with no problem. Powered the radio up, and got a fail 001 message on freqs under 446 Mhz. I read about the 220k resister from pin 4 to ground of the VCO, tried that, with no success. I then bitbanged the bandsplit to a range 2 and success, no more fail 001. Well, success until I powered off and then back on. At first I got a fail 01/90 general hardware fault that cutting the power off and on a couple of times self cleared. Once cleared, the radio operated fine. Powering on the next day the radio went into fail 01/90 and a power on/off loop.

The caps have not been replaced, and I have removed the resister to see if it clears the code, but no luck. I have tried replacing the head with an A7 head and another interface board just to see if it would clear and got the same power loop and message. I just tried read/writing to the radio, but being in the power loop, no go. Is there anything else to look for? Thanks for your time.

Doug

[wa6jbd]

The resistor-on-the-VCO trick is for the 900 MHz Spectras. To convert a Range 3 UHF radio, you have to add some conductive ink to the VCO micro stripline that's visible in the little rectangular window in the shield cover. I've found that adding about 3/16" to the length of the stripline does the trick. Leave the radio as a Range 3! If you have the latest RSS, you can program it just fine.

You'll also find that the receiver sensitivity drops off as frequency goes down. The filter IS tunable, but it's not a job for a beginner, and requires sweep gear. The transmitter just seems to go, but sometimes requires resetting the power settings and current limit settings.

[RADIOMAN2002]

Thats not totally true, I have sucessfully lowered Spectra's to 440mhz with the resistor trick. Now maybe in this instance you are running into the fact that the codeplug has some base frequency set in to for the higher range. I had the same problem while converting a range 3 to work trunked using a range 1 codeplug, the same codeplug worked on a range 2 radio just fine. Try loading a range 2 codeplug in radio, and see if the fail goes away. BTW the front end may not like the stretch to 440. You might be better off trying to get a range 2 radio.

[hfd376]

Thanks for the replies, apparently with the resister I've killed something in the radio, since it will go into the self check, power down and then back on, self check, and so on. I think I need to fix whatever is causing the fail 01/90 before it will power on and I can read or write to the radio. I wonder, is there a fuse on the board somewhere causing the command board to not power up?

Doug