I've got a DX-10 transmitter on 760 kHz. running at 10.5 kW (licensed) that apparently didn't like the bandpass filter at the RF output, since it kept blowing up (literally) the mica caps that are part of the filter. It would run all day at 8 kW, but only a couple to several hours at 10.5. Several thousand dollars (and a lot of caps) later, I finally found the right person at Harris to enlighten me as to the fix.
I had the opportunity to speak with Geoff Mendenhall after a recent SBE meeting, and he graciously took my information about the problem and forwarded it to Jeff Griggs in Quincy. Jeff looked up the Final Test Data for our box and noticed it specified using 293 capacitors. He called me to confirm that's what I had been using as replacements. He then told me they had made a production change on the DX-10's to use 294's due to the higher voltage rating. One more change and a little copper strap (because of the 4" height difference) and the box has been running for over a week now at 10.5 kW.
The micas are used on the lower end of the AM band. You can tell whether you have micas or vacuums by removing the upper filter from the back door and peering in with a flashlight. They are located near the front of the transmitter, to the right of the vacuum variable. If you have the vacuums, you don't have to worry. The 293's are 3" tall, and the 295's are 5" tall.
I thought I'd pass this along in case anybody else is scratching their head over this.
I had the opportunity to speak with Geoff Mendenhall after a recent SBE meeting, and he graciously took my information about the problem and forwarded it to Jeff Griggs in Quincy. Jeff looked up the Final Test Data for our box and noticed it specified using 293 capacitors. He called me to confirm that's what I had been using as replacements. He then told me they had made a production change on the DX-10's to use 294's due to the higher voltage rating. One more change and a little copper strap (because of the 4" height difference) and the box has been running for over a week now at 10.5 kW.
The micas are used on the lower end of the AM band. You can tell whether you have micas or vacuums by removing the upper filter from the back door and peering in with a flashlight. They are located near the front of the transmitter, to the right of the vacuum variable. If you have the vacuums, you don't have to worry. The 293's are 3" tall, and the 295's are 5" tall.
I thought I'd pass this along in case anybody else is scratching their head over this.