Using my radio keying 10 watts continuous into a maco 104c, I was able to tune it to a very low SWR. After connecting the amplifier in line, the SWR went high again at the radio. I've read threads regarding the use of antenna matchers between the radio & the antenna, but I'd like to ask if somebody has ever tried to solve the spikes in SWR that I'm experiencing by placing one of those matchers between the radio and the amplifier. I believe that the mosfets in my 2970n2 do not tolerate high swr, so I'm looking to protect the radio. The SWR at the post-amp end remains within my acceptable levels (1.6:1). Will an antenna matcher solve the high SWR between the radio and the amp?
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Will an antenna matcher work?
- Thread starter Wire Dawg
- Start date
An antenna 'matcher', 'tuner' only does one thing. It transforms one impedance to another impedance. If there's an impedance mismatch between two devices then a 'matcher'/'tuner' can change one impedance to another so it ends up as if there's no impedance mismatch. So, yes, a 'matcher'/'tuner' between the radio and the amplifier can 'solve' an undesirable SWR at that point. The mismatch is still there, but it's been 'changed' from one to the other. So why not do it that way? Because it can be done in a much simpler way, by correcting the circuit that's supposed to be doing that transformation to start with, the input circuit of that amplifier. By adding -another- impedance transforming device between the two will also add a little bit of 'loss' in the signal going from one to the other unnecessarily. Depending on just how bad that impedance mismatch is the 'loss' may not even be noticeable, but there is going to be one. If there's already an impedance transforming thingy there, and it's not working correctly, why not fix/adjust that existing transforming device instead of adding another one? The most common answer to that is that 'fixing'/adjusting isn't as simple as just adding another stage of transforming.
The quick-n-dirty answer is that yes a tuner/matcher can 'correct' the apparent problem. The 'catch' is that there is a loss associated with that 'correcting', there ain't nothing free. If the 'cost' is less than the effort to do it 'right' then I'd have to say do it.
So, which way do you, want to/have to, do it?
- 'Doc
The quick-n-dirty answer is that yes a tuner/matcher can 'correct' the apparent problem. The 'catch' is that there is a loss associated with that 'correcting', there ain't nothing free. If the 'cost' is less than the effort to do it 'right' then I'd have to say do it.
So, which way do you, want to/have to, do it?
- 'Doc
Why were you Unable to Properly Tune the SWR of your Antenna.
It can be hard to do at times..
But it is worth it to get it right and your station working well.
It can be hard to do at times..
But it is worth it to get it right and your station working well.
Until I get my base antenna,I'm using a old radio of mine with a modulation meter,swr/power meter,and a antenna matcher/tuner feeding a piece of 18 gauge automotive hookup wire exiting the house and pointing down at a forty-five degree angle and tied to a guy wire but insulated from it. I have another wire screwed to the back of the radio and falls to the floor,running along the baseboard acting as a counter poise. The matcher/tuner adjusts the impedance and the power output of the radio. It's just temporary. A weird kind of inverted v dipole. It works.
Right! It's far from a perfect dipole. I just wanted something to listen to the locals in the house. Got tired of sitting on the car. Plus I'm saving my coax I just bought for the soon coming base antenna.
Thank you. I was able to obtain a 1.3:1 SWR when going straight from the radio to the antenna (as measured by an external SWR meter). After placing the amp in the path, & connecting the meter at the point between the amp & the antenna, the SWR remains at 1.6:1 (which is ok for me). The situation that Im trying to solve is that the built-in meter on the radio tells me that the SWR between the radio and the amp is terrible. In trying to protect the radio (which is set to key 10 watts rms-going to 60 PEP on modulation) I have questioned if the use of the antenna matcher may solve the anomaly. The radio's 6" tail is connected straight to the amp, so there are no jumpers.
The radio's 6" tail is connected straight to the amp, so there are no jumpers.
You might try different lengths of coax between the radio and the amplifier till you find one that modifys the input 'z' of the amplifier to value that will produce a low swr to the radio.
Jumper in 3' or 6' or 9' lengths of coax (or a combination of these lengths) in trial and error method.
Once that is acomplished you will want to check the swr with the amp in the bypass mode to see if the additional coax alters the swr of the antenna system to an unacceptable value.
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