Search found 83 matches

by mbrockm
Wed Jun 27, 2012 3:31 pm
Forum: AM Radio
Topic: 2nd Harmonic above normal
Replies: 16
Views: 3147

Re: 2nd Harmonic above normal

Talked to our consultant yesterday and raised similar thoughts that the measurements may not be totally accurate. Measurements were made with a spectrum analyzer without a filter on the fundamental. The 2nd was readable on the FIM but barely from a mile out. Need to do more measurements with a FIM t...
by mbrockm
Mon Jun 25, 2012 10:41 am
Forum: AM Radio
Topic: 2nd Harmonic above normal
Replies: 16
Views: 3147

2nd Harmonic above normal

Just did our NRSC. Everything look fine until we started looking for any local interference on the spectrum. Our 2nd Harmonic is about 74db down from main carrier while non directional with modulation. 84db down no modulation. Even a couple of miles from site. Switched to backup transmitter same res...
by mbrockm
Mon Mar 19, 2012 9:26 am
Forum: AM Radio
Topic: Collins 820E relay
Replies: 1
Views: 894

Collins 820E relay

Got a question about the power relays in the Collins 820E. I recently replaced a burnt up relay for the screen supply. Coil fried. Fortunately had an exact replacement on the shelf. The relay coil has 2 windings connected thru a micro switch. I assume that is to keep relay cooler after it engages or...
by mbrockm
Thu Mar 15, 2012 10:02 am
Forum: FM Radio
Topic: FM processing talk format
Replies: 16
Views: 2455

Re: FM processing talk format

Yes. I have made several changes to our audio chain and multiple tweaks to the VP8. Not real happy with the VP8 in terms of adjusting it. Seems like every setting I changed, caused a major increase in the output from the processor. I had some real nice loudness several times until I realizied I was ...
by mbrockm
Wed Feb 29, 2012 1:51 pm
Forum: FM Radio
Topic: FM processing talk format
Replies: 16
Views: 2455

Re: FM processing talk format

Another related question. Is it better to use the stereo generator/ encoder in the processor or the one in the exciter? Does either way tend to give a better sound? The transmitter is a NV30.
by mbrockm
Wed Feb 29, 2012 12:56 pm
Forum: FM Radio
Topic: FM processing talk format
Replies: 16
Views: 2455

Re: FM processing talk format

I got a call back from Wheatstone and they are going to look at our current preset settings. They will send us back several possible new presets. The VP8 GUI seems like we have tons of control over the processor setting. My problem is figuring out what managements wants it to sound like and how to g...
by mbrockm
Wed Feb 29, 2012 9:21 am
Forum: FM Radio
Topic: FM processing talk format
Replies: 16
Views: 2455

FM processing talk format

We changed our FM to a talk / news format a couple of years ago. We have a VP8 processor (not the plus). The management wants me to change the sound of the station. They want it to be "brighter" and to be "louder". Their words. I have started with the basic "talk" settings that came with the box. Ca...
by mbrockm
Tue Feb 14, 2012 9:18 am
Forum: Everything else
Topic: Lighting a 1000' tower
Replies: 5
Views: 1067

Re: Lighting a 1000' tower

This is for an existing tower but, I can't say much about our current lighting system due to a settlement agreement. Due to the NEPA study, we seem to be limited to a strobe system which has been a headache to maintain. So I am charged with determining if there are better options. Is there a "low ma...
by mbrockm
Tue Feb 07, 2012 9:44 am
Forum: Everything else
Topic: Lighting a 1000' tower
Replies: 5
Views: 1067

Lighting a 1000' tower

Looking for more detailed information on costs to maintain and operate various lighting systems on a 1000 ft tower. What I am wanting is the expected maintenance on a High Intensity strobe system. In a typical year what fails and how often? I would expect it to be mostly flash tubes. Is that correct...
by mbrockm
Thu Sep 15, 2011 7:07 am
Forum: STL Engineering
Topic: STL 10 Audio Levels
Replies: 4
Views: 1920

STL 10 Audio Levels

I have 2 STL 10 transmitters. Units have similar problems lacking audio drive to the modulator. The audio board appears to be common components that could be replaced for a few dollars. Could anyone give me some idea of expected audio levels after the various audio op amp stages? Or at least what au...
by mbrockm
Thu Oct 21, 2010 7:22 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

Always the last place you look. The problem was no rf drive to quad 2 on the PA amp. The connector on the RF splitter was not completely seated. Back to full operation. Thanks for all your help Sam.
by mbrockm
Sun Oct 17, 2010 2:12 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

The display readings are now pretty much back to the original factory readings. I checked the PDM balance after the PDM generator started working and set it. Haven't tried swapping PA amps yet. At the rate I am going thru these $10 FETs, however. What ever is wrong is shorting out all the FETs in th...
by mbrockm
Sat Oct 16, 2010 12:09 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

I have our SX5 working for the most part. I am down to one quad section (quad #2) which keeps blowing fuses and IRF 350 FETs. Found the two UDZ718 Zener protectors shorted replaced but still blowing fuses and FETs after replacing. Oddly noted that many rectifier and diode components don't exist on o...
by mbrockm
Mon Sep 13, 2010 6:17 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

It was the A3 PA board. Not the combiner transformer board. Damage was not as bad as I thought once I got the char off the board. Damage on the top side was hard to see. Ate a 1/2" hole in the PCB where one of the FETs used to mount. Did some creative rebuilding and so far its holding. Only problem ...
by mbrockm
Fri Sep 10, 2010 6:04 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

Found my problem. Major melt down / short on one of the PA boards. Fried the PC board. Anyone have a PA board from a SX5 I could buy.!!! Contact me at kmaengineering@kmaland.com if you do. Thanks.