Search found 575 matches

by kcbooboo
Thu Feb 13, 2020 5:15 am
Forum: Ask the Engineers
Topic: AM signal interaction?
Replies: 4
Views: 218

Re: AM signal interaction?

I run spectrums for a 1kw station that's 40 kHz and 3000ft from a second 1kw station. When mine was running IBOC, I'd manage to get the other station to shut down for 10 minutes so I could get a decent trace, because they'd show up at -40dBc at the IBOC sample port on my TX. Signals more than 75 kHz...
by kcbooboo
Sat Jan 25, 2020 8:09 am
Forum: FM Radio
Topic: HD Portable Radio with split audio capability
Replies: 5
Views: 493

Re: HD Portable Radio with split audio capability

The table radio sold by RadioShack some 10? years ago could do that. Some of the tuners can do that and they usually have a headphone jack on the front.

Bob M.
by kcbooboo
Thu Jan 09, 2020 3:51 am
Forum: FM Radio
Topic: Smart AC Power Circuit Breaker with Web Control?
Replies: 18
Views: 573

Re: Smart AC Power Circuit Breaker with Web Control?

The phase loss relay would have detected an incoming phase loss and dumped the transmitter. This was an internal phase loss of the power feeding the SCR controller's three small transformers. I know a lot of engineering went into the SCR control circuit between the Collins and Continental versions, ...
by kcbooboo
Wed Jan 08, 2020 5:42 am
Forum: FM Radio
Topic: Smart AC Power Circuit Breaker with Web Control?
Replies: 18
Views: 573

Re: Smart AC Power Circuit Breaker with Web Control?

"Some of those continentals were known for nuisance plate breaker trips with no discernable cause." I worked on one such unit that was tripping the breaker every few days due to a phase loss internal to the TX. After replacing a couple of SCR modules, the SCR driver boards in the card cage, one of t...
by kcbooboo
Tue Jan 07, 2020 5:30 am
Forum: FM Radio
Topic: Smart AC Power Circuit Breaker with Web Control?
Replies: 18
Views: 573

Re: Smart AC Power Circuit Breaker with Web Control?

Reminds me of the photo in RadioWorld magazine's Workbench column that showed a Continental Electronics FM TX circuit breaker being pulled up/on through a rather large externally-mounted solenoid? Seemed like a clever idea but I too agree that you really want to be present when restoring power. Bob M.
by kcbooboo
Mon Jan 06, 2020 5:10 am
Forum: AM Radio
Topic: Gates 5--no audio
Replies: 28
Views: 1240

Re: Gates 5--no audio

"They operate very well until a lightning strike hits the tower." I think that applies to just about every transmitter. One MW-1/1A in my area does seem to be quite susceptible to any nearby lightning strike, not just on the tower, and it will blow out diodes in the SWR/feedback circuit even when of...
by kcbooboo
Sat Dec 07, 2019 5:52 am
Forum: FM Radio
Topic: Wind Farm
Replies: 6
Views: 729

Re: Wind Farm

Airplanes flying overhead definitely affect the 50-54 MHz amateur FM band, just like they do with analog TV signals. It manifests itself as a rapid-to-slow-to-rapid fluttering of the signal strength as the signal bounces off the plane. Even stations 45 miles apart using vertical polarization have th...
by kcbooboo
Thu Nov 28, 2019 5:28 am
Forum: Ask the Engineers
Topic: Ampex VPR-80 analog 1"
Replies: 3
Views: 591

Re: Ampex VPR-80 analog 1"

"The same tapes that give problems will play fine the next day so I'm sure the tape isn't the problem."

See Jeff's item 4 above, assuming the tapes are in good enough condition to survive FF and REW once or twice.

Bob M.
by kcbooboo
Wed Oct 16, 2019 10:22 am
Forum: AM Radio
Topic: Equipment Performance Measurements
Replies: 6
Views: 525

Re: Equipment Performance Measurements

Thanks. In my case it's a very local station (less than 2 miles away) so travel isn't an issue. The CE will get around to fixing it because there are multiple issues and the transmitter just had two PA modules repaired by BE. It's just going to take time before he can get it added to his project lis...
by kcbooboo
Wed Oct 16, 2019 2:49 am
Forum: AM Radio
Topic: Equipment Performance Measurements
Replies: 6
Views: 525

Re: Equipment Performance Measurements

Well I started with the IBOC measurements right at the transmitter. Those failed. High baseline noise level and more than just a few peaks exceeded the IBOC mask and even the 73.44 mask. We noticed the mod monitor seemed to be reading low negative modulation so we spent a few minutes checking the ba...
by kcbooboo
Mon Sep 23, 2019 4:12 am
Forum: Everything else
Topic: IS GATES AIR STILL THERE?
Replies: 9
Views: 449

Re: IS GATES AIR STILL THERE?

A local engineer needed some BE RF modules repaired. Called BE, got a recorded "Leave a message and we'll get back to you later today" and never got a call back. Called again two days later, same message, finally got a call back. Sent two modules in. They found half a dozen bad parts on each one. Th...
by kcbooboo
Mon Sep 16, 2019 7:33 am
Forum: AM Radio
Topic: Equipment Performance Measurements
Replies: 6
Views: 525

Re: Equipment Performance Measurements

Thanks. I really don't know when the main will be back in full operation. I think they're using it at night when they run lower power, then switching to the backup during the day for better coverage. They already sent two RF modules to BE for repair and that took 3-4 weeks. When they came back, one ...
by kcbooboo
Sun Sep 15, 2019 1:08 pm
Forum: AM Radio
Topic: Equipment Performance Measurements
Replies: 6
Views: 525

Equipment Performance Measurements

It's that time of year again. One of the stations I do spectrums for, is running on their backup TX because the main has one PA module out for repair. Does it matter if I take spectrums while they're on the backup TX as long as I document the conditions that existed at the time, or should I wait for...
by kcbooboo
Fri Aug 30, 2019 6:24 am
Forum: Ask the Engineers
Topic: Marti Crystals
Replies: 6
Views: 487

Re: Marti Crystals

The biggest hurdle will be getting new crystals. International Crystal Mfg closed. Bomar isn't really an option. Your best bet would be to send the oscillator schematic and maybe even an old crystal to http://www.quartslab.com/ QuartsLab over in England. I've worked on a couple of Marti units. They'...
by kcbooboo
Sun Aug 25, 2019 5:16 am
Forum: FCC Discussion
Topic: AM station to shut down at end of May 2019
Replies: 23
Views: 1620

Re: AM station to shut down at end of May 2019

Apparently they filed a "Silent STA". I don't know if that's the same as surrendering the license. I also heard that they inquired about taking the towers down. That pretty much means they'll be selling the equipment and property pretty soon afterward.

Bob M.