Sidebar Sidebar
  • You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
  • Click here to find out how to win free radios from Retevis!

Change in antenna causes change in power?

MFJ makes a good antenna analyzer. They are not the only ones around that make good analyzers. There are others that seem easier to use. I honestly can't tell you which is 'best', or would be easiest for you to use, or the cheapest. I can tell you that a decent one is not going to be cheap, you are talking about $200-300 dollars. I was also not kidding when I said not everyone needs one unless they do a LOT of antenna work. I -was- kidding about me doing this sort of stuff commercially, I don't, and certainly don't plan on getting into the business! (Unfortunately, wasn't kidding too much about the beer part.) I would suggest seeing what that local shop would charge for doing that checking for you. And, being naturally cheap, I would do some shopping around for the best price on that too.
This post is a salve for my conscience. I don't want to be responsible for anyone buying something they may only need once or twice, and that 'something' not exactly going for 'pocket money'. ... unless it's true about all them truck drivers making all them millions of dollars!
- 'Doc
 
W5LZ said:
MFJ makes a good antenna analyzer. They are not the only ones around that make good analyzers.
- 'Doc
Click to expand...


I have only seen the MFJ in use twice, the local shop does not charge for hooking it up and only charges for actually tuning. The MFJ's operation seems easy enough.

I seem to remember there being a bunch of models, specific to frequency? Which model do I need? I seem to remember there being several different units that would "work" for 11M?

What are the other options, I only know of MFJ...
 
Rob KI6USW said:
Sounds like it needs to be a tad longer still. It is a lot harder to make it longer than it is to make it shorter. Does any company make parts to extend this setup a couple of inches?
Click to expand...


A guy by the name of "Gunslinger" did make a 102 "adjustable" base that basically was a heavy tube the stinger slid into and was held at a particular length with set screws (very similar to the adjustment on many antennas). I am not sure if he still makes them or not...

I removed the spring, and used a piece of all-thread in place of the spring. Its not as easy to adjust because you start long and literally trim the all-thread with a hacksaw. But it is a set and forget method...

I also considered a 108" from MFJ, but my spacer works well with my $20 RatShack whip...if I bend the 102 up, I will buy a 108...
 
Hey jerk, what is the problem with running your antenna system with a 1.4:1 -1.5:1 swr? you are only loosing about 10% of your signal if that much, and that is probably on the high side by 6%?
 
Before resigning yourself to hook up a lossy tuner; why not go to that shop and settle the issue. Just let them check it out with the antenna analyzer and do it right? I don't know what you think is right - but that is what I would do. If they have the equipment and expertise - go for it dude!
 
If I had the MFJ myself, I could experiment at my leisure...and I'm not sure the local shop (the one near Reading) has that expertise...if he does, he doesn't "share" it with everyone.
 
I'm sorry, the only antenna analyzer I'm familiar with is the MFJ-259, which is one of the current models. The only difference with the other one they currently offer is the range of usable frequencies, into the UHF regions, which you just don't need. Different prices depending on where you buy it, but figure around $275 +/- a few, sort of.
Other companies do make them, I'm just not familiar with them, which doesn't mean anything at all. Some have a slightly different way of displaying the same information any of them give you. That's personal preference I guess.
The hard part is learning how to use them, what the provided information means. If you really enjoy that kind of stuff I'd have to say an analyzer is a good investment. If it's a sort of 'occasional' thing, save your money. There are also one or two that do all this stuff on a computer. They are not going to be a 'bargain basement' sort of thingy. And just how likely is it that you just happen to have a computer handy when doing this stuff? Find a copy of a half way recent 'QST' magazine, they have lots of advertisements of this kind'a stuff. So, knock yourself out with it. Or just put it on the 'to-do' list.
- 'Doc
 
purenrg said:
First of all there is no way a 102" steel whip is going to give you a 1.1:1 swr period end of sentence !!! It's more like around 1.4:1 / 1.5:1 is what you should be seeing, Unless your using a antenna tuner between your meter and antenna.

The length of your coax is probably showing you a better swr than what is actual there. You need to calculate the electrical length to get the rite swr reading.

This is the rite way to calculate the electrical length not the physical length,
of the coax.
#1 The coax needs to be 1/2-wavelength or it's multiple 2/2, 3/2, 4/2, 4/2, ect.
#2 You need to know what the coax velocity factor is, for a example RG8/x has a VF of 78, RG8/U -80, RG213/U -66
#3 SO a 1/2-wavelength ( in feet ) = 468 divided/ the freq.(MHz) x the velocity factor say of 0.66

So say 1/2-wavelength of coax at 27 MHz is about 11.44' physical length, when using this length of coax it would be like checking the swr reading at the antenna.
Click to expand...
Another old post but, sorry, mine does.
A Breedlove mount with a very old heavy duty barrel spring and a quick release then the 102 on top. 1.1 on channel 1 and 1.2 on 40. If I remove the quick release, then it's exactly the opposite. 1.2 on 1 and 1.1 on 40.
 

dxChat
Help Users
  • No one is chatting at the moment.


      Top Bottom
      Back