[Elecraft] K3 - Numeric SWR Display

[O. Johns]

An adequate and not too expensive vector analyzer is the VA1 by Autek  
Research.  It reads resistance and reactance (including its sign)  
directly and also has a function that automatically calculates the Z  
at your antenna even though you are measuring at the rig end of your  
transmission line.  It is tiny and and battery operated and hence can  
be used on balanced lines without unbalancing things very much.
I have no connection with the company, just a satisfied customer.  Use  
google to find them.

--Oliver Johns
    W6ODJ

On 17 Sep 2008, at 3:52 PM, Bill W5WVO wrote:

> I should add that you CAN adjust an antenna for minimum SWR at the
> transmitter, but when you do that, you are in all likehood
> including some non-zero feedpoint reactance in the net impedance,
> and this is being observed through the length of your transmission
> line, which then becomes part of the overall load the transmitter
> sees. If you subsequently change the length of the transmission
> line, you will no longer have Z=50 ohms at the transmitter. If you
> tune the antenna for TRUE resonance (zero reactance, R=50), then
> you can put any length of transmission line on it that you want
> to, and it will behave just the same.
>
> I know we all got along without the MFJ-259B for years, just going
> by guess and by gosh (or sweating over Smith charts), but now that
> we can actually tell what is happening in an antenna so easily,
> it's crazy not to use one. Beg, borrow, steal, or if necessary buy
> one, and learn how to use it. You won't regret it! Greatest thing
> since CW killed King Spark. :-)
>
> Bill W5WVO
>
> ----- Original Message -----
> From: "Bill W5WVO" <w5wvo at cybermesa.net>
> To: "Cranz Nichols" <CranzN at yahoo.com>; "LIST - elecraft"
> <elecraft at mailman.qth.net>
> Sent: Wednesday, September 17, 2008 4:39 PM
> Subject: Re: [Elecraft] K3 - Numeric SWR Display
>
>
>> Actually, looking at transmission line SWR at the transmitter is
> a
>> poor way to adjust an antenna. To get it right, you need to use
> a
>> complex impedance analyzer like the now-ubiquitous MFJ-259B (or
>> equivalant instrument), and put it as close to the antenna
>> feedpoint as possible. Adjust as close as you can get for Xc=0,
>> Xl=0, R=50. You can't do that with an SWR bridge! :-)
>>
>> Bill W5WVO
>>
>> ----- Original Message -----
>> From: "Cranz Nichols" <CranzN at yahoo.com>
>> To: "LIST - elecraft" <elecraft at mailman.qth.net>
>> Sent: Wednesday, September 17, 2008 3:53 PM
>> Subject: [Elecraft] K3 - Numeric SWR Display
>>
>>
>>> I need to adjust the gamma matches on my 10/15M delta loop.
>>>
>>> Is there a way to bypass the internal ATU and have the K3
>> display the SWR it
>>> sees numerically?
>>>
>>> Should dig out my old SWR bridge?
>>>
>>> cln
>>> WB5BKL
>>> K3 #231
>>>
>>>
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>>
>
>
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