Anyone have a good reliable smith chart program download link? And some expertise on input output tuning amplifier. Can you use an antenna tuner on the amplifier input to verify 50ml input? Amp on and manually key the amp?
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Smith chart and amplifier input/output tuning.
- Thread starter Jim5570091
- Start date
tell us more... what amp? what are you trying to do exactly.
on them Palmar / Texas Star type amps I make a good single
input with some resistors. match to the driving radio
for about 3.5 watts drive.
on them Palmar / Texas Star type amps I make a good single
input with some resistors. match to the driving radio
for about 3.5 watts drive.
It’s a XForce straight 10 pill. That burned completely up. I replaced all the pills from Toshiba 2879 red dot with hg 2879 16DO8 matched. Tested all the caps replaced one bad one on an output transformer. New mini coax, new 5 Port combiners/splitters. All new resistors throughout. All matched. I don’t have a dummy load to test with but my antenna has a 1.3 SWR on my other amps. This one come back up with low output and a high SWR of 2.75. It had a 2 turn inductor from output combiner to relay. I played around with different turn and diameter coil. It now has less that 1 full turn It is matching what my other amps show now. The power seems a bit lower on the output wattage. Driving it with a two pill driver dead key 30 watts and swinging around 100 peek. And I see 80 watt dead key out and swings about 850 max. I’m novice and trying to learn. I have a few of my original Toshibas that’s still test ok. I want to use those and experiment with building a 4 pill for my self. After I get this worked out. I’ll post some before and after photos when I get time.
I managed to get this job completed. Photos is completed results. Turns out I was chasing a bad coax and meter. Go figure. Probably what popped the pills originally. But my goal is to understand how to do input/output tuning. On amplifiers of this design.
Not many give up that tightly held secrete!!!!!!! Transformers for input and output, Cap values, number of turns on the transformers, plus other little tricks.
Copy that. I’d just trying to work out a way to know if all that combination is correct by testing.
I use variable caps to test and get the tune right then I put in fixed components. I repair a lot of stuff for the locals and what I buy thats broken. Never built one from scratch but I have rebuilt many that were in bad shape and had mismatched everything. I did buy a 8 pill box kit from ICA to attempt to build one from nothing with the best matched 8 pills I have that I have saved for myself unless the price is right, LOL. I have about 28 used Toshibas still. I have enough to have matched 4-16 pill repairs. I still have not bought the transformers yet, not sure what I should really use, it will be a biased 8 pill.
