I have an odd question, when a radio scans for a radio stations signal it will not stop on our radio station. I thought it might be the code set on our rds unit but it doesn't matter if it is RDS equiped radio or not, if you put a car radio on scan it will not stop on our signal no matter how strong it is. We are running an old Harris-Gates transmitter(1978) ver. on 96.3 FM. Our audio sounds clean and strong even with the old work horse but I can't figure out what would cause this and since the newer car radio's only scan to find a station needless to say the station owner would like to have the problem fixed. Any idea's of where to start would be a great help. Thanks
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Radio scanning will not stop on our station
- Thread starter Gatekeeper007
- Start date
Yep...been there. In my case, it was a Harris TE1 or TE3 exciter. One of the filter caps in the exciter power supply failed & the station was about 30khz off frequency. One thing that scanning radios look for is an on frequency signal. Unfortunately, the FCC caught it (this was in the late 1970's) before I did...no fine issued, but they did want a written accounting of what was done to correct it. Get a frequency counter on your transmitter & verify that you're within the FCC +/- 2khz limits.
I checked it early and sure enough the frequency has droped 28kh to 96.278, I will get on it today. Thanks I didn't think of the frequency being off.
Wow! Glad you noticed the problem with the scanning and checked into it further! That's a pretty big shift in frequency!
Glad to help...Curious to know if it's the original TE-1 or TE-3 exciter that came with the transmitter? In my case, it seems like a large value cap in the power supply had opened up. It didn't add any audible hum to the air signal, but did knock it 30 or 33 khz off frequency.Gatekeeper007 said:
There were very few scanning radios 31 years ago when this happened, therefore what would have been a warning wasn't detected. Not sure how long you've been in radio, but in the late 70's, most people that weren't driving brand new cars still had analog car radios with a tuning knob & a mechanical pointer to show dial position. By about 1980, the radios with scanning & digital readout were becoming common in new cars. After-market radios were mostly all scanning/digital readout by then as well. By then, FM was also becoming the dominant source for music, although the station that had this problem on FM at the time was a Class B automated Country station, the 500 watt daytime AM in the same building had better ratings & was live in all dayparts. How things have changed...
I went in and found a bad cap in the powersupply and changed it. Everything worked great for about an hour then one of the drive transistors in the 10 watt RF stage on the TE3 went out which is funny since they only run 5 watts out of that stage into the main amp. The part number is a PT-3134B boy I hope I can find one. Only reason I can figure the transistor shorted base to emitter 82ohms is it must have been weak and when the voltage increased back up to normal must have took it out. Any ideas where I can find one?
I would assume you've already checked with Harris 217-222-8200. A google search revealed little, although this line 'may' lead you to 11 of them: http://www.netcomponents.com/results.htm?t=f&r=1&d=1&pn1=PT3134B&SUBMIT1=SearchGatekeeper007 said:
That all said, it's time to consider retiring the TE-3...there are very few of them still in use and with the low cost of frequency agile exciters, it's getting hard to justify keeping the really old exciters running (the TE series were among the first solid state exciters made...the model before the TE-1 had tubes in it). If you strike out at finding the output transistor, you may find this to be the ammo needed to get management to buy a new exciter. There are many brands to choose from, but I've had good luck with Broadcast Warehouse & Bext.
I'm not an engineer, but I did grow up on a farm where we farmed with what equipment we could afford. Thank goodness for welders and TSC! All I can say is "Wow", but I understand the effort you guys put into keeping the station on the air. There does come a time when its nearly impossible to find parts for a piece of equipment, whether it be a tractor, transmitter, or space shuttle.OKCRadioGuy said:
BobOnTheJob said:
You probably had a 55 machine too...
Clunk, Clunk, Clunk, Clunk, Clunk
And big reel to reel automation decks with Country Lovin' tapes on 'em...ChiefEngineer said:
The TE-3 I worked with had a strange low frequency AFC instability that I could see on my Pioneer TX7500's tuning meter. Never bothered to figure that one out since it was a backup to a Bext 10 freq agile. Got a call one weekend that the transmitter was off. Tuned to it and it was indeed off. Then by magic it came back on! It's then I noticed the wiggle of the tuning meter. Next day went up there and the Bext was gone and the TE-3 was on the air! Found it a few days later. Another station's owner had borrowed the Bext when his exciter failed. Never bothered to ask or tell us he did that.
The old RCA BTE-15A (Moseley) was really unstable unless you spent some time playing with the AFC board's grounding. Found that removing one screw & insulating that mounting stud cured a lot of the noise problems. They also wandered far & wide if the AFC was disabled or that switch got dirty.
The old RCA BTE-15A (Moseley) was really unstable unless you spent some time playing with the AFC board's grounding. Found that removing one screw & insulating that mounting stud cured a lot of the noise problems. They also wandered far & wide if the AFC was disabled or that switch got dirty.
I bypassed the second stage amp(3134B) and went from the 3134A to the 3134C transistor stages since the 3134A and 3134B have the same build no problem. The RF output came up to 5 watts which is all the main amp needs to run full power. So everythings up and running good again until I can find another 3134B for the second stage of the amp even if it doesn't need it I would like to put it back right.
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