Here's one that baffled me for a bit. This is a report I hear more than once a year. "Can't get a Mark 3 SSB transmitter on channel. Shows power, but not on the channel." This radio baffled the tech who brought it to us. Baffled me for a bit, too.
Sure enough, if you tweaked the devil out of this one it would oscillate and transmit an off-the-wall carrier frequency that would not change with the channel selector.
I used the Kenwood TS930 on the bench to tune in the three internal crystal oscillators and max the tuning slugs on the S-meter for each of the internal frequencies that get mixed together.
Except one. The carrier at 5.6465 was there, and T2 peaked okay. The 16.270 channel 1 crystal signal was there, and L5 peaked like it should. This leaves the third crystal oscillator, 5.0485 for AM. Barely can hear it in the TS930, and turning the slug in T6 has almost no effect. Experience has shown a fairly sharp peak from the slug in T6.
So I swapped T6 for a known-good used part. Bingo! Now the radio transmits on the channel you select. Big improvement.
Couldn't resist pulling the guts out of T6 to have a look.
What's wrong with this picture?
The wire in the black winding SHOULD be the same color as the larger winding. Probably used to be. I have no idea who toasted this side of T6, or how they did it.
The way a tuning adjustment behaves, or in this case misbehaves can be a big deal.
73
Sure enough, if you tweaked the devil out of this one it would oscillate and transmit an off-the-wall carrier frequency that would not change with the channel selector.
I used the Kenwood TS930 on the bench to tune in the three internal crystal oscillators and max the tuning slugs on the S-meter for each of the internal frequencies that get mixed together.
Except one. The carrier at 5.6465 was there, and T2 peaked okay. The 16.270 channel 1 crystal signal was there, and L5 peaked like it should. This leaves the third crystal oscillator, 5.0485 for AM. Barely can hear it in the TS930, and turning the slug in T6 has almost no effect. Experience has shown a fairly sharp peak from the slug in T6.
So I swapped T6 for a known-good used part. Bingo! Now the radio transmits on the channel you select. Big improvement.
Couldn't resist pulling the guts out of T6 to have a look.
What's wrong with this picture?
The wire in the black winding SHOULD be the same color as the larger winding. Probably used to be. I have no idea who toasted this side of T6, or how they did it.
The way a tuning adjustment behaves, or in this case misbehaves can be a big deal.
73
