Adjusting SWR with amp

[T-bone]

You still with us T-Bone ? After a bout with Doc and Beetle you could sometimes be worse off then when you first got started It has a way of getting deeper then one antisapated :? It's all good ! Really sounds like your on your way here dude. That harmonic one had me gasping for air Good defination Beetle

It's definitely hard to understand!! But I do hope to catch on. I keep reading and reading. I only started a year ago from scratch and have learned quite a bit. Smoked a couple pills along the way in the process!!

 

[T-bone]

What I want to know, is why my swr changes when I change jumper length between the radio and amp?
I have to run it like this...
radio--18 ft--amp--any length--meter--antenna
With everything in the same order, but change the radio to amp jumper to a shorter one, swr goes higher the shorter it gets. It does'nt matter if amp is on or off...it's still high, but higher with the amp on.
With the 18ft jumper in there, the swr stays the same with amp on or off, and is the same as what the MFJ analyzer says, when just hooked to the feedline.
Should I just run 18 ft, where I really only need 3 or 6?

Great question Gearhead. I couldn't get my swr down with a 3' jumper and someone told me to use a 6' jumper. That took care of the problem. I have read the 18' antenna coax is a myth though I'm sure many will agree to it. I've also learned that antenna theory and antenna reality aren't even close.

 

[Switch Kit]

copy on smoke'in them pills, Damn if I hate learning the hard way from time to time I think the basics will work for you T-Bone , but the knowledge is still there for you to grasp . The best of knowledge to you.

 

[King Mudduck]

Freecell.....its not so much that i dont know its the fact that it would have taken me all night to type all of that

 

[Gearhead]

When I had my toyota 4runner, I ran a roof mounted wilson 5000, and no matter how much grounding I did, I could'nt get the swr below 1.4 on 1 and 40. With the amp on, it was almost 2:1.
A guy told me to set it without the amp, and then put the amp in place of the meter, and don't worry about it, lol. I NEVER had a problem with that amp, (knock on wood) and still running it in another vehicle.

 

[Chainsawgang]

When I had my toyota 4runner, I ran a roof mounted wilson 5000, and no matter how much grounding I did, I could'nt get the swr below 1.4 on 1 and 40. With the amp on, it was almost 2:1.
A guy told me to set it without the amp, and then put the amp in place of the meter, and don't worry about it, lol. I NEVER had a problem with that amp, (knock on wood) and still running it in another vehicle.

GEARHEAD,
That's the same thing many , many CB guys have told me over the years too. I have the same Wilson 5000 mag w/ only the radio 1.2 SWR now when I turn on the HEAT it goes over 5.0 !!
I get a radio check , & everyone tells me it sounds great & is definitely getting the signal out . What is a guy to do? I tried diff jumpers between radio & amp , it didn't help my SWR at all . I really don't know where to go now? As I said earlier I think I'll try the TVI filter but, I really don't know if it will help.
The main thing is I just don't want to burn the finals up in the Galaxy radio .

 

[Beetle]

Freecell.....its not so much that i dont know its the fact that it would have taken me all night to type all of that

Type it out?

I used Google

 

[Gearhead]

"1.2 SWR now when I turn on the HEAT it goes over 5.0 !!"

Chainsawgang, that sounds like an amp input/output tuning problem to me. Have you ever tried a different amp?
Friend of mine had me look at his base amp, and it was doing the same thing. It was a 6 pill doing 1,000 watts, but people said I had a stronger signal barefoot! lol. When the amp was on, the swr meter was pegged. I had ampower rebuild it, and now the swr is 1.1 with the box off, and 1.2 with it on.

 

[Chainsawgang]

"1.2 SWR now when I turn on the HEAT it goes over 5.0 !!"

Chainsawgang, that sounds like an amp input/output tuning problem to me. Have you ever tried a different amp?
Friend of mine had me look at his base amp, and it was doing the same thing. It was a 6 pill doing 1,000 watts, but people said I had a stronger signal barefoot! lol. When the amp was on, the swr meter was pegged. I had ampower rebuild it, and now the swr is 1.1 with the box off, and 1.2 with it on.

Thanks for the input GEARHEAD ! Man , why didn't I think of that ??? Yes, I have another amp , don't know why I had not thought of trying it to see what happens. DUH !!

I'll try to check it out & see what happens. It may be several days before I post back
Please PM a number for ampower I may need their services or someone else similar. THANKS

 

[Lazybones1222]

So I pose a question. Can the reflected harmonics that may give false swr meter readings damage the finals of a transistor linear?

 

[W5LZ]

Lazybones1222,
The quick-n-dirty answer is yes and no, and sort of, maybe. There isn't much point in distinguishing between what exactly is being 'reflected'. The point being that whatever makes up that 'reflection' is what is causing an impedance apparent to the amplifier (or radio), and that difference not being what the amplifier/radio wants to see is the problem. Getting rid of any harmonics would be nice, if it also did away with enough of the reflected power. But if there's that much harmonic artifact to the signal to start with, then there's somethings wrong anyway (not that likely unless the amplifier/radio is -really- trashy!). Make sense?
- 'Doc

 

[Lazybones1222]

Yes it makes sense. In my case it is a rhetorical question anyways. I just use a Dentron Super Tuner as an RF condom, tune it flat and let er' rip. Works for me.

 

[Chainsawgang]

Lazybones,

Tell me a little about that supertuner . Are they very expensive , readily available ? I have a "trashy " Boomer amp . I should probably get rid of it I hardly evr use it .

 

[Lazybones1222]

Lazybones,

Tell me a little about that supertuner . Are they very expensive , readily available ? I have a "trashy " Boomer amp . I should probably get rid of it I hardly evr use it .

The tuners show your equipment a good feedline match, they do not "untrash" your trashy equipment.

Dentron Super Tuners are readily available on ebay at times- -about $75 to $150 depending on condition. There are 1000 watt and 3000 watt versions.

I have my antenna hidden in the middle of (not sticking out of the top of) a tree for stealth purposes and get reflect based on close proximity to limbs, leaves, wetnes after rain etc. so my swr fluctuates. The tuner gives me a flat match regardless of varying conditions and sends the reflect right back out the coax to the antenna thus protecting my transmitting equipment, thus the RF condom comment.

Some say the reflect is disipated as heat in the tuner, but from what I have studied, it is sent right back out the feedline to the antenna.

Comments supporting both views are likely to follow. 8)check out this link also

 

[Beetle]

There's very little in any good tuner that will dissipate power. Inductive and capacitive reactances can NOT do it; the only circuit elements that can actually dissipate power are resistances. The only places in tuners -- MANUAL tuners -- where you'll find resistances as opposed to reactances are in the inductor, the sliding contact on the inductor (if the inductor is the rotary type), the tapped connections on non-rotary inductors, and the bandswitch contacts.

Where the actual heating occurs is usually inside the feedline itself. A 100 foot length of coax - even larger stuff like RG-213 - has more resistance than the tuner, and will dissipate a proportionally larger amount of power.