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Hey, Memphis engineers
- Thread starter radiosaur
- Start date
Since I've never worked in radio and haven't a clue about anything tech-like, could the weather have had anything to do with it? I noticed Dave Brown (who seemed like he really thought he didn't need to be there) kept pointing out that the thunderstorms had very little lightning or hail, despite the severe warnings that kept coming around midnight.
J
jb321
Guest
Every station splatters up and down the dial occasionally..95.7 takes over every station to the left of their dial position...Nobody complains and everybody keeps a job :-\
I'm not a Memphis engineer, really, but I was an engineer and live here now. It's possible you were close to their antenna and being over loaded, or that they had some kind of equipment malfunction and no one was around at night to deal with it. Maybe the PD found the code to the processor and cranked the "more" knob. PD's always want "more", they just don't know how to get it from their end of the business yet.
RadeoEngineer said:
Yeah, I've kind of played around with engineering from time to time myself
It was not front end overload or signal strength. I have since gotten an e-mail from someone who measured it the day after I posted. It was in fact out of band. It sounds better now, but I still don't know the cause, however your thoughts about the PD may just barely be plausable
about 2 years ago 101.1's transmitter started throwing something on 101.7 far outside of the area they should blanket.
you could hear it very well even down into Desoto County. This went on for weeks till it was finally fixed.
I have seen icing cause transmitters to do weird things... The just get to a point where they can't take the SWR. If it comes back again maybe 88.5's feed line has become depressurized or something like that which could raise SWR due to moisture.
you could hear it very well even down into Desoto County. This went on for weeks till it was finally fixed.
I have seen icing cause transmitters to do weird things... The just get to a point where they can't take the SWR. If it comes back again maybe 88.5's feed line has become depressurized or something like that which could raise SWR due to moisture.
VSWR faults don't make the station overmodulate. If anything, they will cause the transmiter to fold back power and reduce any adjacent interference. A physical antenna problem? Maybe, but not likely. Because of the terrain around here, there aren't many multipath problems. Maybe they had an STL problem. Don't know if they are using a digital STL. If so, I don't know much about what can go wrong with them. If it wasn't someone tampering, then I'd say there are issues in the transmitter and / or air chain. But they seem to be gone now.
If 88.5's line has gone dry and there's moisture inside, that wouldn't cause the problem I heard but they defintely will not be overmodulating for too much longer!
Come to think of it, I got my first engineering job because someone let a line go dry, and the station was off the air for 72 hours...
If 88.5's line has gone dry and there's moisture inside, that wouldn't cause the problem I heard but they defintely will not be overmodulating for too much longer!
Come to think of it, I got my first engineering job because someone let a line go dry, and the station was off the air for 72 hours...
It's not that uncommon with some receivers to be able to hear a staion on its adjacent sidebands. My particular receiver is pretty broad and I can frequently hear stations that are well modulated and heavily compressed on their adjacents. It's usually pretty distorted though. If it's clear on the adjacents I would have to believe it's over mod. There's really not much else that could cause that phenomenon. VSWR, dry line, blown out low pass filter would cause other problems but not appearance on adjacents.
I remember hearing WZRR (99.5) in Birmingham a while back putting out perfectly clear and listenable spurs on 99.1 and 99.9 for several days. Maybe you guys can tell me what on earth caused that!
From their transmitter site near downtown all the way to Clanton, down I-65 the spurs were pretty clean. That's about 40 air miles. Musta been one heck of a problem!
I don't know where 88.5's transmitter site is, but I've noticed them heavy on first adjacents in midtown and downtown several times.
From their transmitter site near downtown all the way to Clanton, down I-65 the spurs were pretty clean. That's about 40 air miles. Musta been one heck of a problem!
I don't know where 88.5's transmitter site is, but I've noticed them heavy on first adjacents in midtown and downtown several times.
There are a number of propblems that can casue spurs. I'm not sure if QOX is using a tube transmitter still but poor tuning plus other issues can cause them. The FCC doesn't like it when it happens. When I started this thread, 88.5 in fact a little out of band, so a little birdie told me...Does anyone know if Pat Lane is still taking care of the WQOX site? I can't imagine him letting this happen.
The tower is roughly at the northwest corner of Shelby Farms (the WKNO site). If you're hearing clear audio on the adjacents downtown on a decent quality receiver they may have problems again.
The tower is roughly at the northwest corner of Shelby Farms (the WKNO site). If you're hearing clear audio on the adjacents downtown on a decent quality receiver they may have problems again.
It would be interesting to know what model exciter they are using. The HARRIS DIGIT can spur if it develops voltage regulator problems, I have also had DIGITS to spur if some of the caps dry out. The HARRIS MX-15 will emit signals two channels up and two channels down from the fundamental if the electrolytics in the plug in RF amp dry out....there are 2 20 uf caps on the 15 watt circuit board.
I have also had rare situations where an FM transmitter will mix the signal of a nearby fm transmitter in the rf cavity and retransmit the resultant intermodulation.
I have also had rare situations where an FM transmitter will mix the signal of a nearby fm transmitter in the rf cavity and retransmit the resultant intermodulation.
radiosaur said:
My head already 'sploded several years ago. All the hairs fell out too. I only know of Harris Digit problems that cause a high frequency whine due to dried caps. I can't imagine a mix in the cavity getting through the LPF to cause spurs, but I also couldn't imagine two amorous field mice turning a power tube to sand internally because one of them liked the sensation of their tale across the screen voltage circuit. He could have been a huffer for all I know, but being fused to the floor must have been more than he was looking for. His girl friend got out but may have had enough of warm, noisy places with lots of air flow. I saw her but she didn't want to exchange pleasantries. Well I was swinging a big broom at her ass.
Most low pass filters cut off at 108 Mhz to protect the aircraft band and not all transmitters have 2nd harmonic notch filters. The lpf will vary from model to model. I have had the phenomenon occur twice in different smaller markets. Most Spurious problems I have encountered are usually due to exciter problems. The early HARRIS DIGITS were prone to a few different failure modes that would cause splatter or spurs. One problem was with using the AES/EBU input driven by an 8200 with the hpf turned off.
As mentioned earlier, it would be interesting to know the model of the exciter on the offending station (also the tx and antenna model).
As mentioned earlier, it would be interesting to know the model of the exciter on the offending station (also the tx and antenna model).
I did notice the systems analysation of the proton infusion ratings differed greatly from the spectrum titration filtering monitor. I do feel the radium readings and photon libation meter showed that the station was metering in the correct parameters of ifd resonance.
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