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Bob Musil

Transmitter Only Sounds Good During Day

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Thank you for the suggestion, Paul. I may go up in the attic tomorrow and check that.

I just got down from the roof; I had my wife in the car listening while I adjusted the length of the antenna. I went from the shortest possible length to almost the longest, and she could not tell the difference. I don't know if there could be a problem with my antenna, since it is supposed to be adjustable.

After dinner we are going to try something we hadn't considered earlier. With my wife in the car adjusting the radio, I will sit here at the transmitter and adjust 1 step at a time, and see if we can find a good frequency.

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Max, that was in response to Bob's post at the top, and I think I misunderstood what he was saying. 'Skip' is not an issue here. I thought Bob was shooting for trying to do some skipping himself, and without a bit more power that's simply not going to happen.

FM stations are pretty much line of sight, which is the reason for tall antennas (to get around the curvature of the earth). Of course skipping is possible, but it's unreliable as a guaranteed means to lengthen broadcast distance. That's why you Ham guys get so excited when it happens.

Wouldn't you agree that the main differences between day and night are simply the sun's effects on the ionosphere, and in the daytime creating a much more destructive medium for radio wave propagation? Therefore, nearby radio stations on the same frequency, even 70 to 100 miles away can get through and mess you up at night much more easily than daytime. Their signals are simply destroyed by the effects of sunlight during the day and don't mess with you as much.

Sure, Bob might have a coupler or cable problem that is causing a loss of signal, but it's highly unlikely that this is a day/night phenomenon, but rather something that's there all the time and should be fixed anyway. He might also have a severe antenna mismatch and reflecting all his power back into his transmitter, but this isn't real common either.

I guess what I'm saying is that what Bob's experiencing pretty much happens to all of us, simply due to the fact that we don't transmit much power at all. I'd hate for Bob to spend too much time trying to find a problem that really doesn't exist simply due to the nature of what we're doing. Your first suggestion of looking for a new station is probably the best one I've seen for this problem.

Just looked back up above at Bob's recent post...... with a 5 watt transmitter hooked up properly, he shouldn't have any problem at all blowing away distant stations, so perhaps looking into the hookup problem might have some merit. When transmitters run too hot, you definitely want to look at antenna mismatches. Perhaps the transmitter was damaged last year from running too hot for too long?

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chuck,
I agree with your assessment. Seems that Bob was kind of slow with the "rest of the story" (Paul Havey's little saying). Now knowing that he has a 5 watt transmitter and so does FCC. I would say that his statement that it ran rather hot might means that he cooked his finial transmitter transistor. Which means he has a transmitter putting out less power than one of them Whole House transmitters.

This puts a whole different light on things. Now knowing that he has a 5 watt transmitter that hot rather hot last year. And this year it is running cool.

Bob, get a new transmitter. Sounds like your fried this one. This folks is what happens when you have a transmitter with a few or more watts. Dumping into a load that is not tuned. the finial gets cooked. Bob, if you know how to solder. Find a replacement finial transmitter transistor and replace it. then buy a 16db 5 or 10 watt attenuator. this will bring you down to about 125mW which will keep you legal or darn close to it and if your swr is a bit high it will not cook your finial transistor.

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Max-Paul wrote:

Bob, get a new transmitter. Sounds like your fried this one. This folks is what happens when you have a transmitter with a few or more watts. Dumping into a load that is not tuned. the finial gets cooked. Bob, if you know how to solder. Find a replacement finial transmitter transistor and replace it. then buy a 16db 5 or 10 watt attenuator. this will bring you down to about 125mW which will keep you legal or darn close to it and if your swr is a bit high it will not cook your finial transistor.



I honestly have no idea what finials, attenuators, or swr, mean. I guess I have a lot more to learn :shock:. I have experience with soldering plumbing, but not electronics. I also cannot afford to buy a new transmitter this year, so it sounds like I may be stuck.

I will probably try to pick up an EDM transmitter for next year (I have seen several good reviews both here and on Planet Christmas). The problem that I have is distance. As I understand it, you need to transmit a distance of less than 200 feet to be in compliance with FCC regs. My problem is that, with 15 acres, it is farther than that to the road. Any advice on how to broadcast far enough that people can reasonably hear our show, while not upsetting the FCC, would be greatly appreciated.

My plan was to test different frequencies tonight and see if we could find one that is reasonably clear. Thanks to a septic tank problem, that will have to wait a day or 2.

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One other question at the moment. My show was audible 15 miles away both friday and today, in the day. If the transistor was fried, how is that possible?

Please note, I am not trying to be snarky. I really want to get a better understanding of all of this.

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If you're still getting that type of range during the day, then I'm still betting on nearby station interference. The best thing you could do in this case is find another channel.

You might not want to keep mentioning that 15 mile range though..... :shock:

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That sounds like far more than expected day/night issues to me. It sort of sounds like the damaged coax issues we chased for a while, where we were getting better results with an antenna on the ground than with 25 feet of TML-250 and 20 feet of elevation. Changing to a new cable fixed our issues.

Sounds like you are either having intermittent issues with your cable, connectors, or antenna, or your transmitter is cutting in and out.

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chuckd wrote:

If you're still getting that type of range during the day, then I'm still betting on nearby station interference. The best thing you could do in this case is find another channel.

You might not want to keep mentioning that 15 mile range though..... :shock:

Geez, now the poor guy isn't going to get any sleep...

Bob..odds are, the FCC guys are NOT going to come take you away and lock you in solitary..they have bigger fish to fry, with a budget that can barely buy them paper clips. If you had everyone around you complaining to them, then thats another story...

But after reading all the posts, and some of the new information, my opnion only, is to invest in a new transmitter, either now, or off-season (plenty of posts here giving you pros and cons of each..), and then spend some serious time making sure your antenna system is in solid shape.

Whether or not you have an issue that dictates changing freqs, it would seem that you have enough equipment issues, to where you need to deal with that issue second, if you need to deal with it at all.

And, if you don't have any experience soldering, working with RF equipment, etc...repairing the transmitter you have is not the best first-time project..

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Not being snarky at all Bob.

My first comments were based on half information. I had no idea that you where running a 5 Watt transmitter. So, many come in here complaining about the range on their Whole House transmitter with a range of about 60'.

Still dont have a full picture of your set-up. Haven't looked up the antenna you have. Ya, have to agree, 5 watts should not be fading out at your local cause of distant transmitters over powering you at night. this has gone from a fairly cut and dry problem to just plain weird.

Hey you never did come back and tell me what you hear on what ever frequency you had your transmitter on. IF you turned it off and sat in your car at night.

Ok, BTW I called it skip earlier cause there is a lot of technical jargon I didnt want to start throwing around. First the Ionospheres lower at night. This kind of helps keep the ground waves closer to the curvature of the earth. Thus they travel further. The only other possibility is That I have seen where for what ever reason. Be it the terrain and or large iron ore in the ground or large water ways near by. Your location my be a funnel for stray R.F. energy. I just can seem to see anything other than you have a loose or bad connection at the antenna or the actual connector on the coax. Making and breaking contact as the temperature changes. Or you are at a focus point for stray R.F.

I understand your problem with having a large lot and needing a wee bit more power to make it back to the street. Several options come to mind. First is that you remote your transmitter to the street. Of course you are going to need to be able to get the audio to the transmitter with no noise added to the signal. Or use a transmitter with a bit more power to get to the street and just a bit more. But no 15 miles. Thats just waving a red flag under a Bulls nose.

At this time, all I could do is check connections. I think someone bought a SWR meter for the Amateur Radio 2 meter band and below (lower frequencies).

Quick class. SWR (Standing Wave Ratio). ya right! And I still say it today. In more simpler terms that make more sense to me also. Let me ask you this first. Do you build up your own stereo system? Have you ever built or seen one that uses speakers other than 8 ohm? Do you know that if you use speakers other than what the system is rated for (4 or 8 or 16 ohm) that it will not sound as good, right?
Well transmitters are like that too. Most transmitters are rated for 50 ohms. And even if you use 50 ohm coax, it will not matter if your antenna is to long or to short. Cause the antenna will then look like a higher or lower resistance and we would say that your antenna system is not matched to the transmitter. It is a concept that is hard to fully describe in a few paragraphs. An Analog signal is called a sine wave. Where as the first half looks like a hemisphere that starts on the horizon and curves up and then back down to the horizon. the second half is a hemisphere that continues down and then curves back up to the horizon. Just for basics now, not going to talk about 1/4 waves or other fractions. Lets just talk about a full wave antenna. At 300 Mhz a wave length is 1 meter in length. This is the distance that R.F. magnetic wave will travel in the time it takes for the wave to do one cycle, as I described above. So, a full length antenna would need to be 1 meter in length. If it is say 3" shorter. There would be energy that is not fitting on the antenna and it would be reflected back into the amplifier transistor. This would be converted into heat. To much heat and you destroy the transistor. But a small amount of this would not destroy the transistor, but would subtract from power that would actually go into the radio wave that is received by the receivers.

See if you know any Ham radio operators that might have a SWR/power meter that can help you check out your problem. We as a group of people are becoming fewer and fewer.

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Okay, a bunch of stuff here.

First, I went up on the roof and tried adjusting the length of the antenna, to make sure I was using the right size for the frequency (I mentioned this in an earlier post). Sitting in her car, my wife could hear no difference. We lengthened and shortened the antenna as much as possible, with no audio change. Did I possibly fry the antenna?

Next, I went back and looked at the coax I used last year, and it is 75 ohm. If I used 75 ohm instead of 50, which appears to be the recommendation for the antenna, would that have damaged the antenna and/or the transmitter?

Finally, we sat in the car and watched the show ourselves for about half an hour last night. The signal seemed to pulse. Most of the time thee was a lot of static, but sometimes it would pulse pretty clear. The volume also seemed to pulse up and down. Am I correct in assuming that this is another indication that something is fried?

Between time and money, it is too late to replace anything for this season, but maybe I can learn something for the future. Thanks.

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Bob, I have a question for you. I have the same antenna you do, and the connectors on my antenna cable look like the following:

Antenna%20Cable%20(Medium).jpg

On the end of the cable that goes into the antenna, which connector does yours look like?

The reason I ask is if your connector looks like the lower one, you have the wrong connector. Oddly enough, it screws right into the FMA200, and you'd think you did it correctly.

Your connector has to be like the upper connector (male) for you to have a good cable/antenna connection.

Chuck

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Not sure how the N connector would sometimes make good connection, and not others, or how it would pulse in and out, but stranger things have happened. And I agree it feels like it fits together right, but sure does not.

For short distances (5 feet?) Ramsey gets away with 75 ohm cable, but I think their antenna may be tuned for 75 ohms as well.

If you can find some 50 ohm cable, it might be worth a try. Reflected energy from the transition from 75 ohm cable to 50 ohm antenna might be overheating the unit, and it may be reducing power by design or impending thermally induced failure.

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I do know that the FMA200 has a specified impedance of 50 ohms, and I'm personally using LMR400 cable which has a characteristic impedance of 50 ohms. I'm not sure, but I don't think Ramsey makes a cable like Bob is using, so it seems as if this was built by somebody else and not Ramsey.

Also, Bob is using RG58, which has an impedance of 50 ohms. If it were RG59 it would be more of a problem.

When I was hooking my system back up this year, I connected the wrong end of my cable to the antenna first, then wondered for about 5 minutes why the other end wouldn't screw on to my transmitter. Then I had a 'duh' moment where I figured out the cable was backwards. If I had built my own cable, I could have easily but the female connector on both ends and thought everything was great, because it would screw on the antenna and the transmitter just fine.

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Those aren't different genders, those are different series of connectors. Take a look at the bottom of the antenna when you take it down. It looks totally different from the other end of your cable. And the back of your transmitter looks nothing like the antenna end of your cable.

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You're right, I was guessing that they were different genders. I do know for sure that the top connector is the one the FMA200 wants, though.

Just something quick to check.

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I see where I got 75 ohms from. It was what he used last year.

I'm pretty sure you can't fry a FMA-200 with a 5W transmitter.

I wish I could remember what the dc resistance of the FMA-200 is. I really think he may have an intermittent or partial open somewhere in the system. For example, a faulty, or corroded barrel connector. If it is a near short, he could disconnect the transmitter, and measure through the cable. A high resistance would be a cable flaw. If the antenna is open circuit DC, he would have to disconnect both ends, short one, and measure the other.

He might do better with a 5 foot cable, and the antenna indoors. Unless he is in a metal building, or has severe topology problems, he has plenty of power to get through the walls.

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Here is what I have: http://www.radioshack.com/product/index.jsp?productId=2103483

I have a 20 foot section connected to the antenna, a connector in the attic, and a 10 foor section running to the transmitter. At the moment, the transmitter is sitting on a cardboard box about 4 feet from the computer.

Actually, we may have at least temporarily solved the problem. My brother-in-law came over this evening. With him on the roof adjusting the antenna, my wife in the car checking the radio, and me at the compiter/transmitter, we did a series of frequency checks. We finally settled on 94.1 as the best frequency.

While double-checking this, my BIL mentioned that the static sounded like over-modulation from a stereo turned up too high. I adjusted my system volume down to 30%, and most of the remaining static went away.

There are still a couple of things that confuse me. First, tuning the length of the antenna is making zero noticeable difference in the reception. Did I fry the antenna, or is the length really not that important, or ???

Second, the reception and the voulme are still pulsing between strong and week. Ant ideas what could be causing this?

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Antenna tuning will only affect your range, not what it sounds like within your range. No amount of antenna tuning will fix over modulation.

Also, having the clamp loose, and a person touching the antenna will totally alter the tuning.

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Right, touching the antenna will detune the antenna. But if he who is touching the antenna and starts to move things around starts to feel a tingle, then he is going the wrong way. LOL Voltage on the antenna will go up with SWR going up. Or that might be at the far end only. LOL

Right, Now if your car stereo had a S Meter like C.B.s do and you drive away till the meter is about half scale. I suppose you could adjust it some and the S meter might rise or dip to give you some idea. But then your car receiver does not have a S meter. So, back to earlier suggestion. Find a Ham Radio Op and see if he has a SWR meter that will work up to the 2 meter band.

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