Search found 10 matches

by apache45
Thu Sep 12, 2019 9:40 am
Forum: FM Radio
Topic: HARRIS Z-16HD SINGLE PHASE
Replies: 3
Views: 633

Re: HARRIS Z-16HD SINGLE PHASE

Among bad filter boards, PA modules, ribbon cables, etc, the root cause was arching on the "B" side combiner board, especially around J-11 and a couple of connectors. Problem solved. Thanks to everyone who offered help.
by apache45
Thu Aug 22, 2019 11:41 am
Forum: FM Radio
Topic: HARRIS Z-16HD SINGLE PHASE
Replies: 3
Views: 633

Re: HARRIS Z-16HD SINGLE PHASE

Well it turns out that all 4 power supplies are good and functioning normally. The problem is traced down to the B-plane. When B-6 is pulled only half of the rest of B's draw current, but B-6 still shows current draw. WHen B-6 is re inserted, it draws current but none of the rest of the B's draw any...
by apache45
Wed Aug 21, 2019 12:32 pm
Forum: FM Radio
Topic: HARRIS Z-16HD SINGLE PHASE
Replies: 3
Views: 633

HARRIS Z-16HD SINGLE PHASE

I'm at my wits end. After going thru temperature and control issues, I now have on of the 4 power supply's not drawing much current. Probably less than half of the other 3. PS controller boards are good and all fuses on PS are good. Any one have a low PS current problem before? Thanks gang
by apache45
Thu Aug 30, 2018 12:02 pm
Forum: FM Radio
Topic: High Pitched Tone in FM Audio?
Replies: 27
Views: 4076

Re: High Pitched Tone in FM Audio?

In an HT25, we found the IPA was the culprit by bypassing it and running 150-watts direct into the PA for over an hour at 80% power. No whistle, noise, etc. Replaced the IPA it all is perfect.
by apache45
Fri Aug 03, 2018 12:21 pm
Forum: FM Radio
Topic: High Pitched Tone in FM Audio?
Replies: 27
Views: 4076

Re: High Pitched Tone in FM Audio?

We recently experienced a very similar whine in a HT-20/25. It happened shortly after the original MX-15 was hit by lightning so we replaced the exciter with a new Gates/Harris unit but the whine was still there. To keep it brief, we found the IPA stage was creating the issue by running a 100 LP-FM ...
by apache45
Thu Aug 02, 2018 7:44 am
Forum: FM Radio
Topic: HARRIS DIGIT EXCITER
Replies: 6
Views: 618

Re: HARRIS DIGIT EXCITER

Thanks for the response but, no, there is no VSWR as I am using a thru-line wattmeter into a dummy load.
Checked all cables & connections and they appear to be solid and working. I may have to get back into the A-2 card for more serious inspection, however.
by apache45
Thu Aug 02, 2018 6:27 am
Forum: FM Radio
Topic: HARRIS DIGIT EXCITER
Replies: 6
Views: 618

HARRIS DIGIT EXCITER

I have one of the original Harris Digit (not CD) exciters that will not put out any more than one watt. I have rebuilt the A-2 power supply section and all 4 voltages are correct. The APC voltage is also within tolerance. The manual troubleshooting chart suggest "debugging" U-8, U-3, U-7 in the A-2....
by apache45
Mon Sep 01, 2014 4:34 pm
Forum: Ask the Engineers
Topic: HARRIS HT-20 plate overload
Replies: 10
Views: 1968

Re: HARRIS HT-20 plate overload

Well so far, I've tried most of the cures that have been posted and didn't really find the actual culprit. A couple of dirty connectors, sticky toggle switches, a bad cap in the bias supply (thought that was it) which did give me better bias current. After 5 hours of pecking, cleaning, measuring, ev...
by apache45
Mon Sep 01, 2014 8:09 am
Forum: Ask the Engineers
Topic: HARRIS HT-20 plate overload
Replies: 10
Views: 1968

Re: HARRIS HT-20 plate overload

Thanks to all who have responded. Some of the things mentioned have not cured the issue. I've stood in front and watched the metering and nothing spikes (PA current, VSWR). Thought it may have been a controller card which I replaced last night but it has gone off 3 times since early this morning. Pl...
by apache45
Fri Aug 29, 2014 9:06 am
Forum: Ask the Engineers
Topic: HARRIS HT-20 plate overload
Replies: 10
Views: 1968

HARRIS HT-20 plate overload

I have a Harris HT-20 FM that runs great and has always been very reliable, EXCEPT recently I have been having a plate overload for no reason. All obvious things have been done, new tube, proper tuning, etc. It will just shut down, show the overload, but can be brought up even by remote. I have even...