Spectra UHF mid power receive tune

[radiocat37]

I have an excellent condition Spectra D44KXA7JA5BK. I was able to add conductive pen ink to the VCO and everything works to 440.00. Both RX and TX VCO lock good. The receive however, isn't as tight as I would like. Around 440.00 monitor is showing about 1.1 uv. At 442.00, goes to .75uv and at 446 is about .5uv. Is there a way to adjust the sensitivity? This radio works perfectly otherwise in the UHF HAM band.

Thanks,
Mike

[Will]

The receiver filter is one piece and not tunable.

Some have screwed around with the conductive stuff but it has problems.... NOT RECOMMENDED.

[Jim202]

I have an excellent condition Spectra D44KXA7JA5BK. I was able to add conductive pen ink to the VCO and everything works to 440.00. Both RX and TX VCO lock good. The receive however, isn't as tight as I would like. Around 440.00 monitor is showing about 1.1 uv. At 442.00, goes to .75uv and at 446 is about .5uv. Is there a way to adjust the sensitivity? This radio works perfectly otherwise in the UHF HAM band.

Thanks,
Mike

I have used the brute force method and just blobbed solder onto the ceramic discs to lower their tuning point. It may take a few tries, but you can get it better than what it is by leaving the front end alone.

Jim

[Will]

I have used the brute force method and just blobbed solder onto the ceramic discs to lower their tuning point. It may take a few tries, but you can get it better than what it is by leaving the front end alone.

Jim

Another bad idea, the coating/plating on the receiver resonator is VERY thin, and heat will lift the plating.