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Bird RF Watt Meter Questions

W5LZ said:
A tuner is only an impedance transformer. Just like one you plug into the wall to get 9vdc from 120vac, it only changes/matches impedance instead of voltage. That changing, or matching is done -quite- often with a lot of antennas only it's done at the antenna instead of sitting on a table by the transmitter (gamma, beta, 'trombone', delta matches, etc.). It's a simple fact that the input impedance of almost all antennas is very, very seldom 50 ohms with out 'help'. Those coax length thingys do exactly the same thing, just in a different way.
"But tuners have losses!", yep, they sure do. But those losses are typically very small in relation to the loss you'd have if it wasn't used. (Back to those gamma, delta, etc, impedance matching devices, same thing.) Any, and everything, you insert in a feed line contributes losses of some size or other! If those losses amount to less than not using one, then you are better off. That's the whole point of matching impedance to begin!
Can a tuner be used incorrectly? Good grief, yes! Anything can be used incorrectly. The 'trick' is understanding what the thing is intended to do and what it's limitations are. Are tuners a 'cure all' in every case? No! But they can certainly make an unsuitable antenna work in a usable way in a lot of cases.
If you have the choice between using a properly tuned antenna system or using a tuner, then use the properly tuned antenna. If you can't properly tune an antenna and you have a tuner, why not? That applies to not just antennas, but any device that has the 'wrong' impedance.
- 'Doc
Click to expand...
Thanks and yes,I now know the concept of what one does. Thanks to everyone who contributed.
 
Ok. I sent my amp off to have it looked at. I spoke with Carl over at Bell's CB and he walked me through some troubleshooting over the phone. He seems to think there is an impedance mismatch between the amp and my radio causing the high SWR readings. He's gona take a look at it and let me know. Hopefully this will solve my problems without having to spend a bunch of money on more equipment.

The amp should be there tomorrow. I'll let you guys know what he says once he takes a look at it. Hopefully I'll have it back by the end of the week.
 
Ok. I sent my 500w amp off to Bell's to have it looked at. While it is gone I decided to take my Texas Star DX 350 HDV out of my truck and try it out in the house on the base. I hooked it up and am not having any of the high SWR readings or getting the antenna warning light on the radio with this other amp. I also received the Autek WM-1 Computing Meter that I ordered last week. I took some readings with my current Astatic SWR/Power meter and wrote them down. I then took the Astatic meter out of line and replaced it with the Autek Meter. I will say that neither of the meters readings matched each other. I am inclined to believe the Autek meter though over the Astatic meter. For one, I know the power that my radio was set at because I requested it be tuned to those power levels specifically. The Astatic meter was reading power levels way above what it should have been for my barefoot radio. Also, the Astatic meter was reading basically a 1.0 to 1 SWR ratio on every thing I tested it on. In the house, In the truck, etc. The Autek meter is giving readings more inline with what the meters on the face of the radio are saying. While this proves that my SWR was not perfect as thought with the Astatic meter, it is well within limits at 1.2 to 1.3. I am also getting power readings closer to what I would expect on the Autek meter. For instance the amp I am using is dead keying at an even 100w and swinging to 350w which is the peak power capability of the amp.

All in all, I am very happy with the Autek meter. Thanks to RADIOMAN for suggesting this particular meter. It was much cheaper than the Bird meter and seems to be performing better than the Astatic meter it replaced.
 
Ok. I recieved my amp back from being serviced. Im not to happy. Something is not right with this amp. Now when I dead key the amp I get a reading of about 2.0 on the autek and radio SWR meters. They both read almost identical during dead key. Once I begin to speak or put audio in to the mic the radio SWR meter goes up and the Autek meter goes backwards and actually drops. WTF is going on here? While the SWR was a bit high on both meters before the amp was serviced, at least both meters agreed and moved in the same direction. As stated in my previous post, while my 500w amp was being serviced, I brought my 350w amp in from the truck and did not have any of the high SWR issues or meters going in opposite directions. Anyone have any idea what could be going on here? Im getting to the point where im pissed. Im not having much fun and im tired of throwing money away.:sad:
 
Sounds like there's a bad coupling cap in the T/S 500, or possibly the choke got burnt. Those two problems are common with the T/S 500's, especially if they get over-driven.


Do me a favor if you can.... pop the cover off the T/S 500, and take a good, clear picture of the inside, up close. I want to see how much has been fiddled with inside.



I'll try to help you best I can.


~Cheers~
 
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Here are some pics ET.

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Sniper, You have my thanks.


Looks like both the chokes, the one just right of the relay, and the other one that's right of the meter, have both been replaced, and are of incorrect value. Also, that looped wire behind the power switch, that connects to the power control buttons is also incorrect. It should be just a small length jumper wire. I bet someone was trying to "fix" the input SWR issue by looping that wire behind the buttons. The transistors have been replaced at some point too. Definitely been boogered with. Sorry to have to be the bearer of bad news. You can get replacement chokes on Ebay, or thru RF Parts, I believe. Can't remember if Texas Star will sell parts or not.

Good luck on getting it going. :)


~Cheers~
 
Cheers

I'm gonna get ahold of a buddy of mine, he has a guy he sends all his Texas Star amps to for repair, and I'll get back to you with some info when I can.


~Cheers~
 

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