I am match tuning swr on 1 and 40. I have a 6666 and a 400HD amp. I have a meter in the radio and one after my amp. I was told to tune from the after amp swr meter with the amp and radio on low, They are reading the opposite swr from each other. Hard for me to tune to match exact. Both are still off and not matched but I tried to make them off matched the same. I can't get either to match exact or one meter goes way off than the other if i try tuning either way. My swr is showing about a 1.7 on channel 1 and around 1.3 on channel 40 at the radio and about that exact opposite after the amp. Channel 19 is showing 1.5 on both(the radio blinks 1.5 1.4, meter showing 1.5). First time I actually tuned using a meter after the amp. Does any of this this even sound normal? Thanks in advance.
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Dual SWR Meter setup tuning help.
- Thread starter 530
- Start date
The meter on the radio is not reading the antenna when the amp is on. It is reading the input tuning of the amplifier.
As for the meter after the amp, that’s reading the antenna. Tune the antenna to that one. SWR at this meter shouldn’t change amp on or amp off.
As for the meter after the amp, that’s reading the antenna. Tune the antenna to that one. SWR at this meter shouldn’t change amp on or amp off.
Ok thank you. I got, tune it exact at the meter after the amp don't worry about radios meter.
Also noteworthy,
The tuning of matching channel 1 and 40 is old CB shop folklore
All this does is give you a balance of an SWR range that could be higher than what the antenna really is.
Better to find the lowest SWR at the frequency you operate most at and let the antennas bandwidth cover the rest.
Most CB antennas should cover all 40 channels. If you could get your most used frequency down to a near flat match, neither channel 1 or 40 should be above 1.7 or less and they don't have to be equal.
Any SWR below 1.9 is perfectly acceptable and will not make a difference on the other end.
This is where a tuner/matcher placed last in line before the antenna can lower the SWR if you feel the need but the antenna SWR is always the same but your equipment sees a lower one.
The tuning of matching channel 1 and 40 is old CB shop folklore
All this does is give you a balance of an SWR range that could be higher than what the antenna really is.
Better to find the lowest SWR at the frequency you operate most at and let the antennas bandwidth cover the rest.
Most CB antennas should cover all 40 channels. If you could get your most used frequency down to a near flat match, neither channel 1 or 40 should be above 1.7 or less and they don't have to be equal.
Any SWR below 1.9 is perfectly acceptable and will not make a difference on the other end.
This is where a tuner/matcher placed last in line before the antenna can lower the SWR if you feel the need but the antenna SWR is always the same but your equipment sees a lower one.
The most critical part of your setup and the most SENSITIVE to SWR - is your AMP - so always tune that amp to the antenna. Try not to worry as much about the rest of the system...AS LONG AS YOU HAVE AN ACCEPTEBLE SWR at the radio from all this...
Now turn off that amp (put it in bypass) and review the SWR from the radio's own SWR bridge thru the amp into the antenna - you should be ok.
IF that part (the Bypass - it should not reflect high SWR with amp in-line but it's not on, in bypass) isn't good, then your whole mess with the I get that... but then this happens - scenarios, then the bypass or something in the line is affecting the results.
Now turn off that amp (put it in bypass) and review the SWR from the radio's own SWR bridge thru the amp into the antenna - you should be ok.
IF that part (the Bypass - it should not reflect high SWR with amp in-line but it's not on, in bypass) isn't good, then your whole mess with the I get that... but then this happens - scenarios, then the bypass or something in the line is affecting the results.
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OK so you are saying tune the line with the meter after the amp and then turn the amp out and check at radio. I believe i did do that while tuning and it was low at the radio. I don't remember what it was but I believe it was 1.3 with the amp off. Raining here today so not sure I can double check today. Do you think I should try and match tune better and then check again? Another thing is I believe i did try matching it at the antenna but It gets to a point where it makes the radio go over 3 on one channel(40 or 1 cant remember which right now) but still low on 19(channel i use). I was in a little hurry hooking it up yesterday so I need to do it again with this info..
Tune the antenna to AMP SWR with the Amp on with the SWR METER at the output of the amp...
Once that's done, remove the SWR meter - hook up antenna line direct to amp - go back to the radio - CHECK SWR using Radios SWR (you said you have an AT-6666) or put the SWR meter in at the radios output line to the amp - but insert all this at the radio side at the radio - or as close to the radio end as possible. Check SWR - if it's tolerable - you're ok.
But remember - you have a Radio that has variable power - so make sure you run the right wattage of power into that amp when you use the amp.
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Wow. First, excellent job on the info. Thank you very much. I will do this today if it clears up or tomorrow and post the results. Foresight questions, what happens if its high at the radio(second part) after match tuning(first part) and also after removing amp meter, and what would you concider too high if it was? Thanks again for your time with this. Awesome.
Well, there are several scenarios to this...
Mostly from the standpoint of "the reactance" the Relay and / or switch bypass does to the signal as a bump in impedance.
The relay is the "Added in" part that is supposed to simply switch the antenna terminals when you send a signal into the amp - the "Sense line" is a simple circuit that turns on when RF sign is present - which then it's used to turn on the relay.
The sense circuit is the only tap that the line should see ever when the amp is in bypass - and there are several versions of the "Detector" that is a basic cap that one leg is put on the line from the "To Transmitter"...
It's when things go wrong - do you see high SWR issues and then you have to stop and fix the damages and replace parts needed to keep the SWR Bump down to a minor hiccup...
Mostly from the standpoint of "the reactance" the Relay and / or switch bypass does to the signal as a bump in impedance.
The relay is the "Added in" part that is supposed to simply switch the antenna terminals when you send a signal into the amp - the "Sense line" is a simple circuit that turns on when RF sign is present - which then it's used to turn on the relay.
- - it's value is a chosen level of capacitance that tends to offset the inductive part of all the wiring that is from the SO-239 to the board,
- It's supposed to be transparent to RF so the sense line tap thru the relay routed back to the To ANTENNA SO-239 would pass thru any SWR reflections or Power transfer from the Transmitter without adding SWR problems to the mess..
- The Starred parts - So the Amp shouldn't be a "Bump" that affects the SWR badly
- - but if the Sense cap got "poked" with more RF than it can handle or its' shunt / Divider circuit is zapped from too much RF from a high power radio or a fault in the Relay terminals on the relay itself - it can cause an SWR issue.
- It (the SWR problem you have) can be the damage that was caused during a "flashover" from the quenching effect from the RF the amp had to deal with had to go somewhere...just as an example...
It's when things go wrong - do you see high SWR issues and then you have to stop and fix the damages and replace parts needed to keep the SWR Bump down to a minor hiccup...
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Excellent. I will be doing it tomorrow it looks like. Thank you, very helpful like you wouldn't believe LOL. Even though I'm no tech I've read many posts and many different answers on this and no explanation was ever given. Thank you.
With the amp off the radio's meter is "seeing" the antenna. It should be close to the same as what the meter after the amp showed.
With the amp on the radio is "seeing" the input of the amplifier...and the radio will not respond to antenna adjustments as it would with no amplifier.
With the amp on the radio is "seeing" the input of the amplifier...and the radio will not respond to antenna adjustments as it would with no amplifier.
Yep thank you, I know that one. I didn't think it would be that far off abeit from flat when i hooked up the amp. And then the swr readings were confusing me. With the power all the way down on the radio which regulates amp power my swr isnt that high, but it has changed. Also which I read doesn't matter in some posts but not sure, when I turn the power up on the radio the swr goes up by the amp meter. One channel is almost a 3 and the other is around 2.2 I am going to take more time now and really get it right as per Handy Andy's advice and go from there. Thanks again.
IMO, the SWR between the radio and the amp should be whatever you are comfortable with (what you feel is safe for the radio’s finals).
At 2+, and certainly at 3, I would be looking to make an adjustment to the amplifier.
FWIW, sitting in the pickup now hoping to catch some afternoon DX. Just flicked to AM to test mine. Shows 1.1 - 1.3 across the frequency range I operate.
At 2+, and certainly at 3, I would be looking to make an adjustment to the amplifier.
FWIW, sitting in the pickup now hoping to catch some afternoon DX. Just flicked to AM to test mine. Shows 1.1 - 1.3 across the frequency range I operate.
Well it goes up at the amp meter when i turn the radios power up which is obviously turning the amps power up, but I read that really didn't matter as it should be done on the lowest power(s), although I myself don't enjoy it LOL. On low power on the radio with the amp on its around 1.3 and 1.5 now. When I turn the radio up to about half max input power the amp will handle, which is how I run them, the swr raises at the amp meter.