FM Transmitters for everyone
Last night I went to work at 9:40 pm. I got home at 20 till 6 this morning. I slept till about 9:10. I am tired.
I work at a radio station. I have transmitter problems. Here's the deal: On an FM transmitter, basically you have the exciter, which puts out about 10 watts, which is FM stereo, on the frequency, the same thing you pick up on your radio, only at low power. then you have your intermediate power amp (IPA), which takes this 10 watts and cranks it up to about 200. The comes the final power amp (FPA) which takes this 200 watts and increases it to 3000 watts (depending on your transmitter) and sends it to your antenna. You control everything by controling the amount of power that goes to your IPA with a little knob like a volume knob on your radio.
Well, I had low power. I had been watching it drop off slowly for months and figured the tube in my final power amp was dying, as it was very old. When I got there to do the work (in the middle of the night), I found that I didn't have enough power coming out of my IPA, But I decided to change the tube anyway, because it was so old, and changing the tube is a really big job, and I had allotted the time for it. When I got done, as expected, I still had low power. Like I said, I didn't have enough power coming out of my IPA, only about 60 watts instead of 200. I had good 10 watts into my IPA. So I changed the IPA. Now I can get plenty of power. BUT, the old IPA has some different connectors on it than the new one, so I have to take the connectors off the old IPA and put them on the new IPA. Also, I have high reflected power between the IPA and the FPA, which probably caused the problem in the first place. So I have to repair the FPA so it doesn't fry my new IPA. I am running at low power so the reflected is lower than the manufacturers minimum.
It's really fun actually.
I work at a radio station. I have transmitter problems. Here's the deal: On an FM transmitter, basically you have the exciter, which puts out about 10 watts, which is FM stereo, on the frequency, the same thing you pick up on your radio, only at low power. then you have your intermediate power amp (IPA), which takes this 10 watts and cranks it up to about 200. The comes the final power amp (FPA) which takes this 200 watts and increases it to 3000 watts (depending on your transmitter) and sends it to your antenna. You control everything by controling the amount of power that goes to your IPA with a little knob like a volume knob on your radio.
Well, I had low power. I had been watching it drop off slowly for months and figured the tube in my final power amp was dying, as it was very old. When I got there to do the work (in the middle of the night), I found that I didn't have enough power coming out of my IPA, But I decided to change the tube anyway, because it was so old, and changing the tube is a really big job, and I had allotted the time for it. When I got done, as expected, I still had low power. Like I said, I didn't have enough power coming out of my IPA, only about 60 watts instead of 200. I had good 10 watts into my IPA. So I changed the IPA. Now I can get plenty of power. BUT, the old IPA has some different connectors on it than the new one, so I have to take the connectors off the old IPA and put them on the new IPA. Also, I have high reflected power between the IPA and the FPA, which probably caused the problem in the first place. So I have to repair the FPA so it doesn't fry my new IPA. I am running at low power so the reflected is lower than the manufacturers minimum.
It's really fun actually.
posted by MarkD60 at 9:04 AM
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