Ts440 uneven am carrier across HF

[WD5JKO]

When I can't see a couple watts on ten meters and see a couple hundred on 160, this is bad.   
Shane
KD6VXI

I don't know if this is relevant, but I had a similar problem with an FT-757. First I lost 10m, then 15m. The RF output was way down on those bands. I was running mobile back at the time, and did a lot of 10FM, and AM. I'd also do some 15m AM. Turned out in my case that in the 757, the RF PA is followed by a band specific filter (half octave I think) to filter out the 2nd and higher harmonics. The parts used were not up to the task of high duty cycle modes like AM and FM. Instead of rebuilding the PCB, I bypassed it with a piece of wire! That allowed all kinds of crap into the RF output, but I regained full power on all bands that way.

I also mod'd the ALC since it based upon the built in Forward Power reading of the built in directional coupler. I merely tacked in a bigger cap across the forward power readback to lessen the peaks going into the ALC sense circuitry. This allowed me to run 100 watts FM at the edge of ALC, but with AM and SSB I could hit around 150w PEP. I am sure the IMD was terrible, but hey, it worked. :-)

Jim
Wd5JKO

[KD6VXI]

Update:

Had a little time to work on the rig.   My son amputated his fingertip via the solid oak door. Since he's on painkillers,  I have to stay home and monitor him... 

Was using it with the fsk jack and my rack gear,  and received more than a couple compliments.....   My favorite was,  "On your next transmission,  please tell me how you get such beautiful audio out of a ricebox".

So,  had to make a good thing better.   Ran a direct line in from. The 'spare'  RCA jack on the rear.  . 01 across it,  rg174 (iirc,  teenie stuff)  with a ferrite bead passing a couple turns through it.   Feeding pin 1 of ic5 direct.. Get it all done,  buttoned up,  turn it on,  ZERO Pout.

Long story short,  reversed the mod,  same thing.   No power out.   Bypassed antenna tuna,  still nothing.   On a whim,  I pulled the IF board towards me,  and power jumped to full!   Put the board back down and as I tilt the board (this is the hinged board) towards its natural position,  I can watch the carrier drop.   FM power on 40 went from the 50 watts I had it set with the board vertical to unreadable with it horizontal.

I pulled it back vertical,  and checked power out on ten.  About 45 watts.   NOT MUCH DIFFERENT!

I still haven't found WHICH wire or connector is causing me problems,  but I do believe I've found the harness.   However,  the radio is working on the bench 100 pct now....   One of those,  let sleeping dogs lie questions.....

Also,  I noticed my ten meter receive sensitivity is a lot better as well.   From Marks post,  this leads me to believe it's from the rf to if board.  Unfortunately,  most of those connections are soldered instead of the coaxial plugins prevalent throughout the radio....   Meaning the boards are going to have to be pulled so I can see underneath.   

So,  as it sits,  I have a working radio with power out even,  plus / minus a few pct from 10 to 160.  I consider this normal.   I just have to find which cable it is lol.

--Shane
KD6VXI