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How much gain with SWR- meter?

 
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How much gain with SWR- meter?
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Tobbstar
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Post How much gain with SWR- meter? Reply with quote
HI, I'm a few steps away from buying the Cyber Max 15W with the Comet antenna. But I'm still unsure if a SWR- meter is neccessary. I know it's used for antenna tuning but how much gain does it have? Can you just send over a longer distance or is there also a difference in signal clarity? What do you think, what distance can I reach without the meter at least and how far could I send with it? I hope you can answer me this last question I'm unsure about.
Sun Sep 17, 2006 5:09 pm View user's profile Send private message
Sir Nigel
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You must tune properly or else your range will be terrible and you'll likely blow your transmitter because of the excessive SWR.

Without an SWR meter you can't really tell how to do it and from experience the chart included with the aerial is very vague.

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Sun Sep 17, 2006 7:58 pm View user's profile Send private message Visit poster's website
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SWR meter is definitely a recommended item.

If you're serious about broadcasting, you'll need to get one
eventually anyway.

Maybe we should assemble a list of recommended things that everyone
should have and post it somewhere in the forum?

For now I suggest these:
- SWR meter

- A selection of various RF connectors and adapters.
These always come handy and if you don't have it handy you can loose hours or days, for example:
BNC male -N female
BNC male - SO239
N male - BNC female
...

- Adjustable mains power supply, 0-15V / 5A, stabilized, with analogue current meter,
often comes handy

- Soldering iron, either one digitally adjustable or a selection of one fine pitch and another
stronger 50-60W

- Voltage/Ohm/Ampere meter

Any more suggestions, Nigel and others?

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Sun Sep 17, 2006 8:44 pm View user's profile Send private message Visit poster's website
cliffyk
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I'll start by clearing up what I perceive as a misconception. An SWR meter by itself does nothing to improve the strength of your radiated signal--it's just a tool that lets you monitor the matching of your transmitter's output to the load presented by the antenna (by adjusting the antenna's element lengths, feed point, etc; depending on the sort of antenna).

An exact explanation of what SWR is and what causes it is far beyond what can be presented here, suffice to say that it can be as high as 3:1 with a nearly negligible radiated power loss (-1.25 dB at a VSWR of 3:1); and that a VSWR of 1.5:1 or less (-0.18 dB loss) is considered to be as good as one needs to wory about. Within reason poor matching of the tramsmitter output and antenna will not affect the "quality" of the transmitted signal, just it's strength.

All this said however without a VSWR meter (or field strength meter to monitor radiated power and adjust for the peak) you are just shooting in the dark and hoping to get lucky. If you a "close enough" sort of person and have adjusted the Comet's elements according to your frequency and the supplied data then you are probably OK--if however you are an anal retentive sort like me that has to have my "mechanical things" just so then an SWR meter is essential.

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Sun Sep 17, 2006 9:11 pm View user's profile Send private message Visit poster's website
Sir Nigel
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I'd also recommend the shortest run of low-loss cable.

Additionaly, audio processing equipment/software with a limiter to give your station that "sound".

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Mon Sep 18, 2006 5:14 pm View user's profile Send private message Visit poster's website
Tobbstar
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Post Reply with quote
OK, thanks a lot for your replys. But what about this figures, e.g. 2:1...? Is this adjustable on the SWR meter via a display?
Why isn't a SWR- meter recommended here: http://www.pcs-electronics.com/transmitter-package-p-291.html
below the topic:
Quote:
WHAT ELSE WILL YOU NEED AND IT WASN'T INCLUDED?
?
I think this figures 2:1... are some kind of proportion between the transmitter and the antenna, isn't it?
These questions must bore you certainly, but please be patient with me, I'm a absolute greenhorn.
Mon Sep 18, 2006 5:19 pm View user's profile Send private message
pcs
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Post Reply with quote
Well, those who deal with radio usually already have SWR meter so we did not
include one.

Depending on the antenna used you may not need it, althought I always recommend
one for making sure things are operating nominally.

For example, our Dominators come factory pre-tuned and you need to specify
frequency when ordering.

PCS0205 as well does not require tuning etc.

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Mon Sep 18, 2006 7:22 pm View user's profile Send private message Visit poster's website
cliffyk
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There are many excellent "beginner" and seasoned pro tutorials on SWR (more correctly VSWR) available on the web--search Google for "Understanding SWR", "SWR tutorial", "SWR meter", etc.

Search and do some reading, all the answers you seek are out there...

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Mon Sep 18, 2006 9:16 pm View user's profile Send private message Visit poster's website
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This is a start:
http://www.pcs-electronics.com/guide_coax.php

Wikipedia deals with these things well, too.

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Tue Sep 19, 2006 12:09 am View user's profile Send private message Visit poster's website
Tobbstar
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Post Reply with quote
OK I have done some reading about SWR meter on google. What is still not clear is how I can change the VSWR. Is it by cutting the antenna?
Tue Sep 19, 2006 1:12 pm View user's profile Send private message
pcs
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Depending on antenna. Comet antenna allows for changing length (its adjustable).
In fact most antennas are either adjustable or wideband and require no tuning.

Some simple antennas require cutting.

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Tue Sep 19, 2006 1:39 pm View user's profile Send private message Visit poster's website
Tobbstar
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Post Reply with quote
Thanks for your help!
When you have an antenna which requires no tuning, do you then also need a SWR- meter? There is then nothing changable, is it?
Tue Sep 19, 2006 6:06 pm View user's profile Send private message
cliffyk
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Antennas sold as "requiring no tuning" perform acceptably within the band for which they are intended--I.e. they may have an SWR of 2.0:1 at one end of the band, 1.0:1 somewhere in the middle, and 1:8:1 at the high end (all depending upon the transmitter's actual output impedance, actual cable impedance, etc.).

To obtain optimal performance you should still tune things up. An SWR meter is an ideal and relatively inexpensive tool for doing so. As Marko stated in an earlier post, most of those seriously involved in broadcasting (amateur, CB, pirate or whatever) would already have one, or several...

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Tue Sep 19, 2006 8:04 pm View user's profile Send private message Visit poster's website
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Post Reply with quote
Precisely.

Besides, it lets you measure output power which makes it possible to verify whether
your transmitter is putting out expected power or not.

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Marko - PCS Electronics
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Tue Sep 19, 2006 11:23 pm View user's profile Send private message Visit poster's website
Tobbstar
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Post Reply with quote
Thanks very much. I think I'll buy a SWR meter. Do you think that a radio- beginner like me would get along with this gadget? I even don't know where I have to connect the meter with the antanna. You told me an excessive SWR can blow the transmitter. How is this when I plug it in the first time and haven't tuned the antenna for a good VSWR, yet. Is there a danger for the transmitter?
Thanks very much cliffyk for your help, I really admire your knowledge!
Wed Sep 20, 2006 2:56 pm View user's profile Send private message
pcs
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Post Reply with quote
When you power the unit up for the first time, you immediately
set the power down to 1/3 or 1/2.

Than you proceed with tuning while keeping an eye on the SWR
meter.

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Marko - PCS Electronics
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http://www.pcs-electronics.com
fax +386 4 2316 128
Wed Sep 20, 2006 4:21 pm View user's profile Send private message Visit poster's website
Tobbstar
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Cool, thank you very much for your spended time to answer my questions!
Fri Sep 22, 2006 3:22 pm View user's profile Send private message
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