[Elecraft] A Good Antenna Length?

[Mel Farrer via Elecraft]

I have always found the the OCF antennas require a sufficient amount of feedline to mask the weird impedances it has.  I have successfully used 135 foot 33% offset fed 4:1 balun with W1JR choke and >100 feet of coax necessary.  I tried to use 22 feet and it was a total loss.  All with <100 watts of course like Jim suggests.  The added length does not add enough loss to account for the change.  


Mel, K6KBE



On Saturday, July 5, 2014 9:50 AM, Dave <dave at g0dja.co.uk> wrote:
 


I tried a 40M OCFD for a while. I gave up on it and went back to a centre 
fed dipole instead.

Even on 40M it didn't seem very good and I was plagued with RF getting into 
PCs and them shutting down or periferals stopping working.  Plus, despite 
the hype, it didn't really seem to work well on other bands.  The Antenna 
analyser was very dismissive, showing resonances outside of the Amateur 
bands and, on some that it was supposed to work on, no sign of any resonance 
at all.

Dave (G0DJA)

----- Original Message ----- 
From: "Jim Brown" <jim at audiosystemsgroup.com>
To: <elecraft at mailman.qth.net>
Sent: Saturday, July 05, 2014 2:24 PM
Subject: Re: [Elecraft] A Good Antenna Length?


> On 7/5/2014 2:05 AM, David Cutter wrote:
>> You might consider an off-centre-fed dipole with appropriate balun and 
>> choke.
>
> Not if you're going to run power. An off center fed antenna generates high 
> common mode voltage, which will fry even the best choke when running 
> power. I wouldn't consider such an antenna at greater than 100W.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to dave at g0dja.co.uk 

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to farrerfolks at yahoo.com