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SWR reading with the amp on.

M

Metal Head

Guest
I understand when you tun on your amp you increase the reflected signal. If you have a low SWR without the amp on and you turn on the amp and it moves up several points is this a true reading or is there something wrong with the amp and will it burn anything up?
 

going up a few points is OK .....lets say you have a 1.1 and through the amp on the high side you read less then 1.5 ...I'd guess to say you were doing alright. Reflective power is another story .....but IM sure somebody will chime in on that one.
 
The SWR is just setting your antenna for Frequency...
At most times center channel CH20..

The reflect comes in to play when you have a BIRD meter
set-up... Then you can put in a 5w slug and point the slug towards the amp...Leaving the amp inline and OFF and reading just the radios reflected power...And then retune the antenna
Or antennas untill your 5w slug barly moves...(like 1 needle width)
Then when you turn your amp on? put in a 25w slug for the reflect and it should not even come close to 1/2 scale..
Most cbers...dont want to spend the few hunderd dollars for this kind of set up....But it really makes a difference in recieve and transmitt...reguardless of what some people might say...
*and annother advantage of that set-up would be you can do a quick check on amps to see if there is a "input tuning" problem on amps...For your buddies or whatever...
*the more reflect in watts you can get out of your system??
The better and more efficient your set-up will be...*
-And the amp will run cooler...and you will actually see more and accurate avg power out of your equipment...

-What i gave is for genneral use...
I personnaly use down to a 1/4w slug for radio reflect tuning and a 5w slug for reflect with the amp/amps on...for every day talking...
IF you are interrested in a set up like this?? Let me know and ill tell you the part#'s to order through RF PARTS...

AM POWER
 
I understand when you tun on your amp you increase the reflected signal. If you have a low SWR without the amp on and you turn on the amp and it moves up several points is this a true reading or is there something wrong with the amp and will it burn anything up?
--------------------------------------------------------

No in you will be ok...As long the SWR'S are not above 1.5...
With the amp on...:)

AM POWER
 
f

Let's say - 1.3 with amp off and then you turn on amp and WHAMMY - above 2 swr. What could be causing this? Poor grounding? All coax, and jumpers are good, and lots of grounding.

LoneWolf TN
 
Dont you need to recalibrate the swr meter when amp is on and if amp has more than one power setting you need to recalibrate whenever you change settings.

If you calibrate for lets say 4 watts and then put amp on and feed the meter with 100 watts the swr meter will move higher till you calibrate to the 100 watts and then check swrs.

this is my understanding, is that correct?

AP :?
 
that's correct. So in other words (as far as I understand ? and this one seems to be a tough one for me ?) You can still have a good SWR reading after recalobrating through the amp on the high side ,but reflective power could still be bad )-: this is the one that loses me ? .......if my car is already grounded to the maximum ,I doubt I would know even where to start to fix something like that ? ......So over the years ,if I have a 1.2 with the amp off ,turn the amp on and recalobrate the swr meter and I then have a reading of less the 1.5 through the amp ? I've always left well enough alone. (weather or not I was reflecting power or not )
 
f

Yes, you must recalibrate the swr meter when you turn amp on. If you don't, the swr reading will peg out all the way to the max. But even with recalibrating, sometimes with amp on the swr will be very high. It has to be reflect or insufficient amp grounding - at least that's my take on it.

LoneWolf TN
 
"I understand when you tun on your amp you increase the reflected signal. If you have a low SWR without the amp on and you turn on the amp and it moves up several points is this a true reading or is there something wrong with the amp and will it burn anything up?"

your understanding is incorrect. if you use more power than is necessary to calibrate the swr meter all you're going to see is higher, inaccurate swr readings.

when you turn your amp on with your swr meter between the amp output and the antenna you're exceeding the minimum amount of power necessary to calibrate the swr meter. most of them will calibrate with as little as 1.5 - 2.0 watts of transmitter power. if you have variable or switched rf power control of the transmitter you can demonstrate this easily for yourself..
 
most will calobrate with 1.5 to 2 watts of power ? yes ....but not all .....a Radio Shack SWR meter for instints will not calobrate with less then 3 watts DK into them (or at least the newer ones over the last 10 to 15 years) So once again ole Switch Kit is wrong again )-: ...20 years and I've been wrong all along )-: and most Radio Shack SWR meters can handle up to 1000 watts according to the distructions ...along with many other run of the mill SWR meters ...OK ......so I take a radio that's do'in 4 watts DK and check my SWR that way and it reads 1.2 .....OK fine ........so I put my radio that's do'in a 20 watt DK on the low side of my amp with a 2 watt DK and calobrate the meter to that and it reads 1.3 .....medium side ,hi side ect. ect. .....It's all a lie !!!!! ....well once again ,after 20 years of this stuff ,IM still getting out loud and proud ,shoot'in skip any damned time I please and so on ....weather it's right or wrong ....one more time it works !! .....and works well at that. (-:
 
Get yourself a good meter and check the radio too make sure SWR is low... (Below 1.3:1) before kicking your amp on.

Re-Cal your SWR meter everytime you make an adjustment OR power change...

Playing around like that I got a 1.05:1 Match with my Imax 2000 and Maco Shooting Star... Not 1.5 ... 1.05 ... With 1.2 KW running through the linear...

Adjust and re-adjust.... Grounding is paramount and definately needs to be on the top of the to-do list...

Adjust... Readjust...Readjust... The lower the better.
 
sounds good to me ,can't really emagine running 1.2 KW ? but that's besides the point ......a 1.1 to 1.3 has always been like a breath of fresh air to me with or without power. It's those 2.5s and up that truly become a challenge for the operator , and one can spend many hours (work) in getting then SWRs down in hopes of better all around breathing......so to speak
 

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