The Radio Information Board

I have a TK380 which will transmit down to the ham bands, but it won't receieve below 450... It seems to me like the VCO doesn't lock that low? Anyone else have this problem, or know how to fix it?

The VCO could go out of lock below 450. This could be confirmed by measuring the voltage on tie point CV. Should be between 0.8v and 4.4v.

I investigated an 880 ver 1 a number of years ago for use at 440mhz. This is what I found. The receiver front end is varactor tuned. As the frequency is changed from high to low, the tuning voltage for the varactor would track the frequency high to low. When you went below 450, the tuning voltage would shoot back to max and stay there. This made the receiver basically deaf in the ham bands. Figured it had to do with a glitch in the firmware and didn't go further with it. I don't know if later firmware resolved this or not.

Hmmm... I wonder if perhaps there would be a way of adding a little bit of capacitance in series with the varactor, to offset the tuning or something like that?

I would wager it IS either a firmware or version issue, as I have a 380 that works
perfectly in 440. It's a version-1 radio, btw.

Although nothing is ever perfect.....my display is dead.

Mine is a version 1 too! I took the radio into the shop, they couldn't figure out how to do it.... Did you have to retune yours at all?