The 301 had a couple of bugs out of the gate. One is the “crab walk” problem on the pre-mix board and the other major one is the one your working on. I wrote an a alignment procedure for the one your on. Seems like an impedance mis match going onto the filter board. As you indicated ?the carrier point that is how I resolved that. Built many of them and they all sound great with good audio reports. To long to go into but can forward alignment instructions if you wish. No need to change anything just realign. I have many parts and spare radios. I thought they would be worth something someday but was wrong. Today, if it doesn’t have a computer connection, what good is it. The Elcon library is a good place to look also.
toggle quoted message
Show quoted text
On Feb 19, 2025, at 3:18 AM, atlasstuff via <
g4fph@...> wrote:
Hi to all in the group!
?
I'm close to the end of repairing an FT-301D transceiver and trying to get the transmitted audio quality sounding anything like 'nice'. It's proving surprisingly challenging.
?
Looking at the transmitted RF spectrum, one issue would seem to be that the SSB filter response is very narrow - more like 2.0 kHz rather than the supposed 2.4 kHz. I've tried moving the carrier point around and different microphones, all with no real improvement. This morning, I grabbed a Filter Unit from my spare radio and tried that. No real improvement:-(
?
I imagine it's possible that the crystals in both SSB filters I have tried have aged the same way and their responses have degraded. If that is the case, then I'm stuck with the problem. I do have a minVNA and could remove the filter to test it, but it would be nice not to have to. The receive audio response with either filter sounds generally OK.
?
I'm wondering whether aged coupling capacitors in the mic. amp. could also be a factor. I've not looked into that as yet.
?
Any experience out there of this issue?
?
Regards,
?
Mark, G4FPH.
?
