i've owned this unit for almost 10 years now. it came from CA and was built by Jack Gittings. I'm guessing it was intended for carrier current. the transmitter is all homebuilt in a commercial aluminum enclusure. it uses a PLL unit shielded in an altoids tin. audio is provided via a car audio chip amp driving a large hammond transformer into a 6AQ5 tube. it came to me with an LPB carrier current tuner.
does anyone have any info on these or own a similar unit?
i need help with retuning the TX output to a new freq. i did figure out the switches on the PLL based on trial and error with the tube pulled and a freq counter inline. i'm just not confident in retuning the tube output section. this thing is so rare, i dont want to burn something up. the freq i used to use in a different location is in use in my current location so i need to move. audio on this thing is simply amazing.
I was hoping someone would come forth with information specific to your transmitter but this hasn't happened.
What I can offer is some general information regarding tuning a tube transmitter. The main thing to monitor is the plate current for the final amplifier, this shoud be adjusted to a minimum or "dip" by adjusting the output tank capacitor. This should be done with the transmitter connected to a dummy load or to the antenna.
If the transmitter has a "drive" adjustment then the method is to advance the drive adjustment upward until the plate current increases slightly and dipping the plate before further increasing the drive stopping when no further increase in plate current is seen with increasing drive. There may also be an output load or coupling adjustiment and if so then this should be set so the plate current is at or below the specified maximum value. If this value is not known then it can be estimated from the tube data sheet maximum power dissipation data.
The main thing is to make sure the plate current is always adjusted for a dip. Keep an eye on the plate of the tube and if it turns red shut it down. A brief period of red hot operation usually doesn't cause harm but avoid it if you can.
Don't be too shy about experimenting since good quality tubes are available in case you you ruin one,
Hope this helps.
Neil
Our go-to guy for manuals and data on old and unusual transmitters is Jeff Station8, who has not been around recently.
Meanwhile, I've heard that name before... "Gittings".
We'll check around.
Things don't look good for Station8 as he told me he may have to give up part 15 for a while. Plus his phone is now Disconnected.
I hope he is back soon as he will be missed. He has done a lot for the hobby.
radio8z i think you nailed it. this thing does have a drive control which threw me. i'll have to set it up on the bench with a meter and a dummy load and try your procedure. i'm not worried about 6aq5's as have plenty.