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Local station bad harmonics on 80 meters
80 is basically useless. 3400 and 4000 I have a Pegged meter WFM signal
from 1380kc station here. I have mini harmonics ever 200kc that basically makes 80meters unusable Its really annoying and the station says they had their equipment recertified 2 months ago Is there a place I can report this in the FCC? The antenna is about 10 miles from me. And they are running 5kw. They are planning and have approval for 50KW now and Im worried that 160 and 80 and possibly 40 could me useless. Thanks Scotty W7PSK. |
Local station bad harmonics on 80 meters
R. Scott wrote:
80 is basically useless. 3400 and 4000 I have a Pegged meter WFM signal from 1380kc station here. I have mini harmonics ever 200kc that basically makes 80meters unusable Its really annoying and the station says they had their equipment recertified 2 months ago Is there a place I can report this in the FCC? The antenna is about 10 miles from me. And they are running 5kw. They are planning and have approval for 50KW now and Im worried that 160 and 80 and possibly 40 could me useless. Thanks Scotty W7PSK. You can simply send a letter to the FCC in Washington DC. However there might not be anything they can do. Some years ago a radio station in Marion IN was causing interferance to amateur radio ops in the area. It seemed that there was a spur that fell in the middle of the affected ham band. When the FCC inspected the instalation they measured the spur and determined that it was below the maximum power limit for such emissions. The result was the hams had to suffer due to a totally legal emission. Dave WD9BDZ |
Local station bad harmonics on 80 meters
"R. Scott" ) writes:
80 is basically useless. 3400 and 4000 I have a Pegged meter WFM signal from 1380kc station here. I have mini harmonics ever 200kc that basically makes 80meters unusable Its really annoying and the station says they had their equipment recertified 2 months ago This is hardly an antenna issue. You do realize that it may not be the transmitter? If your receiver (and you don't specify what it is) hasn't got good strong signal-handling, the station may be overloading it and causing the junk. And at first glance, it wouldn't be obvious whether it's the receiver or the transmitter. Try a different receiver. Put an attenuator between your receiver and antenna, and see what happens to those signals when you increase attenuation. If it's overloadig, there will be a point where the unwanted signals go away that can't be accounted for by the actual attenuation. Borrow a spectrum analyzer, which should stand up well to strong signals since it wouldn't be much use otherwise, and see what signals are arriving at your antenna. If you do see signals that are traceable to the broadcast station, then likely they do have a problem. But if not, it's your receiver. And it may not even be the receiver. There could be something acting as a rectifier, that is picking up the transmiter signal and generating harmonics for your receiver to pickup. A rusty rain gutter, or a bad connection on an antenna, obviously something nearby. You have no reason to doubt the station's word, especially since they do have the rules to follow, and likely are in a worse position than a ham with a bad signal. You are expecting the transmitter to blame because you can't imagine your receiver is at fault. But until you can actually rule out the latter, you have no real reason to blame the transmitter. Michael VE2BVW Is there a place I can report this in the FCC? The antenna is about 10 miles from me. And they are running 5kw. They are planning and have approval for 50KW now and Im worried that 160 and 80 and possibly 40 could me useless. Thanks Scotty W7PSK. |
Local station bad harmonics on 80 meters
Michael Black wrote:
You do realize that it may not be the transmitter? If your receiver (and you don't specify what it is) hasn't got good strong signal-handling, the station may be overloading it and causing the junk. And at first glance, it wouldn't be obvious whether it's the receiver or the transmitter. Excellent suggestion. Try a high pass filter passing everything above 1710 to see if you have an improvement. At least then you will have a good indication if it is a problem of receiver overloading or not ... If you are using a transceiver as opposed to a separate receiver/xmitter (I know, I am an OT) you can use an rf switch to cut out the filter on xmit to "cure" the problem. Regards, JS |
Local station bad harmonics on 80 meters
On Tue, 23 Jan 2007 21:10:38 -0800, "R. Scott"
wrote: 80 is basically useless. 3400 and 4000 I have a Pegged meter WFM signal from 1380kc station here. I have mini harmonics ever 200kc that basically makes 80meters unusable Its really annoying and the station says they had their equipment recertified 2 months ago Hi OM, Sounds like IF images from a front-end overload. Build yourself a 6 or 8 pole Hi pass filter to the antenna input. 73's Richard Clark, KB7QHC |
Local station bad harmonics on 80 meters
80 is basically useless. 3400 and 4000 I have a Pegged meter WFM signal from 1380kc station here. I have mini harmonics ever 200kc that basically makes 80meters unusable Its really annoying and the station says they had their equipment recertified 2 months ago Perhaps it is different in the US, but are not MW stations AM? Jeff |
Local station bad harmonics on 80 meters
On Wed, 24 Jan 2007 08:44:11 -0000, "Jeff" wrote:
Perhaps it is different in the US, but are not MW stations AM? Hi Jeff, Some are digital (but still AM ..um perhaps) 73's Richard Clark, KB7QHC |
Local station bad harmonics on 80 meters
"R. Scott" wrote in message . .. 80 is basically useless. 3400 and 4000 I have a Pegged meter WFM signal from 1380kc station here. I have mini harmonics ever 200kc that basically makes 80meters unusable Its really annoying and the station says they had their equipment recertified 2 months ago Is there a place I can report this in the FCC? The antenna is about 10 miles from me. And they are running 5kw. They are planning and have approval for 50KW now and Im worried that 160 and 80 and possibly 40 could me useless. Thanks Scotty W7PSK. 1 800 CALL FCC |
Local station bad harmonics on 80 meters
Get the AM Brickwall Filter by PAR... It will attenuate the AM signal -40dB at the front end of the radio will should go a long ways towards cleaning up your receiver... Since you have a single station to contend with, talk to Paul at PAR and he will build you one with specific tuning for that station... denny / k8do |
Local station bad harmonics on 80 meters
Why all this stuff about "high pass filters" and such. You are dealing with
a spot frequency, not a band of frequencies. A simple parallel resonant notch filter should do the job quite nicely and still pass everything from DC to daylight except that spot frequency. Jim |
Local station bad harmonics on 80 meters
"Michael Black" wrote in message ... "R. Scott" ) writes: 80 is basically useless. 3400 and 4000 I have a Pegged meter WFM signal from 1380kc station here. I have mini harmonics ever 200kc that basically makes 80meters unusable Its really annoying and the station says they had their equipment recertified 2 months ago This is hardly an antenna issue. I know, but I thought it might be for them or me, so I came here (one of the only groups I subscribe to) You do realize that it may not be the transmitter? Possibly, but You never know, it might have to do with their plans on moving the antenna and upping power or the recent storms we've had. If your receiver (and you don't specify what it is) hasn't got good strong signal-handling, the station may be overloading it and causing the junk. And at first glance, it wouldn't be obvious whether it's the receiver or the transmitter. ICOM 706MKIIG ... Never had a problem in the 2 years Ive owned it, havnt changed anything at my end. Try a different receiver. Ill see what I can find to use, good idea. Borrow a spectrum analyzer, which should stand up well to strong signals since it wouldn't be much use otherwise, and see what signals are arriving at your antenna. If you do see signals that are traceable to the broadcast station, then likely they do have a problem. But if not, it's your receiver. Ill see if I can find one And it may not even be the receiver. There could be something acting as a rectifier, that is picking up the transmiter signal and generating harmonics for your receiver to pickup. A rusty rain gutter, or a bad connection on an antenna, obviously something nearby. only happend in the last month or two the Big clues that make me wonder is if it was a pure Birdie wouldnt it still be AM rather that Wide FM ? Makes me wonder if the TX is FMing some how. You have no reason to doubt the station's word, especially since they do have the rules to follow, and likely are in a worse position than a ham with a bad signal. You are expecting the transmitter to blame because you can't imagine your receiver is at fault. But until you can actually rule out the latter, you have no real reason to blame the transmitter. I used to work at a Station and I know the rules they have to follow, I also know that very shoddy work is done at a lot and just signed off. Ill continue to check my end, but If Ive never heard the birdies before with the same station (Save the 706MKIIG and new coax on occasion) Ive had for 18 years here with no problems until the recent storms and the station has multiple birdies and its in Wide FM rather than AM ... makes me wonder. Scotty W7PSK |
Local station bad harmonics on 80 meters
On Wed, 24 Jan 2007 08:49:21 -0800, "RST Engineering"
wrote: Why all this stuff about "high pass filters" and such. You are dealing with a spot frequency, not a band of frequencies. A simple parallel resonant notch filter should do the job quite nicely and still pass everything from DC to daylight except that spot frequency. Hi Jim There's not much more effort in completely covering a band of problems with a band reject (high pass) filter. The original poster could discover the NEXT broadcaster creating problems when he limited his suppression to the first one. Who needs a chain of notch filters when one would work as well for the entire band? 73's Richard Clark, KB7QHC |
Local station bad harmonics on 80 meters
On Wed, 24 Jan 2007 16:49:41 GMT, "R. Scott"
wrote: it might have to do with ... recent storms we've had. Hi OM, Corrosion is a classic distortion products source that could easily bring the problems you see. 73's Richard Clark, KB7QHC |
Local station bad harmonics on 80 meters
"R. Scott" wrote in message ... with no problems until the recent storms and the station has multiple birdies and its in Wide FM rather than AM ... makes me wonder. go mobile. use a small antenna and an attenuator, maybe the one in the rig will be enough with just a 6" antenna or something like that. if it is indeed local to your shack it should be obvious when you get a few blocks away, then start hunting for rectifiers. it should also be obvious if it is from the transmitter as you drive around it. that might also find it if it happens to be from a 3rd party, like a bad ground wire on a power pole or something. Also, do the test of shutting off everything at the breakers in the house... there is an outside chance, especially with the FM symptom and extreme width, that the AM station is getting picked up by some other device and modulating it... it could be getting into a TV and modulating the color burst, or a computer monitor, a old cordless phone, etc. also check their fundamental and see if you can detect the fm on it, that should be obvious enough also and something you could go demonstrate to the engineer that may show him they have a problem that developed after their certification. |
Local station bad harmonics on 80 meters
Dave wrote:
"R. Scott" wrote in message ... with no problems until the recent storms and the station has multiple birdies and its in Wide FM rather than AM ... makes me wonder. go mobile. use a small antenna and an attenuator, maybe the one in the rig will be enough with just a 6" antenna or something like that. if it is indeed local to your shack it should be obvious when you get a few blocks away, then start hunting for rectifiers. it should also be obvious if it is from the transmitter as you drive around it. that might also find it if it happens to be from a 3rd party, like a bad ground wire on a power pole or something. Also, do the test of shutting off everything at the breakers in the house... there is an outside chance, especially with the FM symptom and extreme width, that the AM station is getting picked up by some other device and modulating it... it could be getting into a TV and modulating the color burst, or a computer monitor, a old cordless phone, etc. also check their fundamental and see if you can detect the fm on it, that should be obvious enough also and something you could go demonstrate to the engineer that may show him they have a problem that developed after their certification. Phew! That's a lot of stuff! However, if all that fails, call Ghost Busters! Regards, JS |
Local station bad harmonics on 80 meters
Because he's got a SINGLE frequency interfering with his station. To hell
with covering the entire band. A single parallel resonant network will do something in the order of 80 dB of rejection if the L and C are at LEAST something reasonable for Q. Care to calculate the order of filter that will do 80 dB as a low pass filter? And the Q of the components necessary to make the insertion loss negligible at 160 meters? Jim "Richard Clark" wrote in message ... On Wed, 24 Jan 2007 08:49:21 -0800, "RST Engineering" wrote: Why all this stuff about "high pass filters" and such. You are dealing with a spot frequency, not a band of frequencies. A simple parallel resonant notch filter should do the job quite nicely and still pass everything from DC to daylight except that spot frequency. Hi Jim There's not much more effort in completely covering a band of problems with a band reject (high pass) filter. The original poster could discover the NEXT broadcaster creating problems when he limited his suppression to the first one. Who needs a chain of notch filters when one would work as well for the entire band? 73's Richard Clark, KB7QHC |
Local station bad harmonics on 80 meters
RST Engineering wrote:
Because he's got a SINGLE frequency interfering with his station. To hell with covering the entire band. A single parallel resonant network will do something in the order of 80 dB of rejection if the L and C are at LEAST something reasonable for Q. Care to calculate the order of filter that will do 80 dB as a low pass filter? And the Q of the components necessary to make the insertion loss negligible at 160 meters? Jim Krist! Whatever was I thinking? Yanno, if he even just sits back and thinks about it long enough, he might be getting excited over his present problem for nothing! Maybe if he just practiced a little Zen he could learn to actually enjoy it? Many roads lead to the same destination--the high pass is but one ... Regards, JS |
Local station bad harmonics on 80 meters
"RST Engineering" ) writes:
Because he's got a SINGLE frequency interfering with his station. To hell with covering the entire band. A single parallel resonant network will do something in the order of 80 dB of rejection if the L and C are at LEAST something reasonable for Q. Care to calculate the order of filter that will do 80 dB as a low pass filter? And the Q of the components necessary to make the insertion loss negligible at 160 meters? At the very least, it's far easier to put in a single LC notch filter to see what it does to the offending signal. I was trying to think of things that could be done easily to determine whether the problem is actually the transmitter or simply receiver overload. One can easily assemble an LC circuit in the broadcast band with available parts to try this out, while a high pass filter requires paying good money for it and likely mail-ordering, or at the very least ordering multiple coils to build up such a thing. My first receiver was a cheap low end solid-state Hallicrafters in 1971, and it overloaded terribly. I don't think anything could have been done to fix it, but I know one time I took the parts list from the Handbook for the high pass filter that was in there to solve the problem of AM broadcast stations, and the parts store said they didn't have the coils in stock, and they'd cost a pretty penny (certainly a pretty penny for a 12 year old). Michael VE2BVW |
Local station bad harmonics on 80 meters
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Local station bad harmonics on 80 meters
also check their fundamental and see if you can detect the fm on it, that should be obvious enough also and something you could go demonstrate to the engineer that may show him they have a problem that developed after their certification. Bingo, I just went to thier fundimental and in FM and WFM I can understand the radio perfectly ... Nice and clear. Weirdness. Scotty W7PSK. |
Local station bad harmonics on 80 meters
On Wed, 24 Jan 2007 17:50:56 -0800, "RST Engineering"
wrote: Because he's got a SINGLE frequency interfering with his station. He reported a single frequency, that does not limit the problem to a single frequency. I already explained that. Care to calculate the order of filter that will do 80 dB as a low pass filter? That is not particularly difficult, quite common in fact. Standard engineering syllabus teaches us that you enjoy a 6dB/Octave or 10dB/Decade roll-off for each reactive element in a filter. I already suggested a 6 or 8 pole filter which brings us up to your 80dB for an entire band, much less a single frequency. Slam dunk simple. I am quite sure that many here that are experienced in actual bench work would nod in agreement that the better part of a project is building the things around the electronics - like an enclosure, connectors and such - than with the electronics. 8 off the shelf items (actually 4 pairs) vs. 2 with one of the two needing to be variable AND tuned? Is that such a major demand on the bench skills of an amateur radio operator? And the Q of the components necessary to make the insertion loss negligible at 160 meters? For receive? C'mon now. And 160M instead of the band he is interested in, 80M? Anyone can contrive to fail, that's plug simple. The next set of restrictions will have us going down the garden path to build a crystal lattice filter for the sake of unneeded astronomical Q and to achieve spectacularly low insertion loss - turn up the RF gain. The issue is moot with the probability the issue revolves around spurs from corroded, weather beat connections. I have a buddy who suffered identical issues from an AM station 1 mile away. He wire brushed poor joints and solved the problem that filters couldn't solve. 73's Richard Clark, KB7QHC |
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