[600MRG] WG2XIQ U3 Experiment - loading a 102" pipe on 630m

[John Langridge]

Ed,

Not a crazy idea at all.  I've seen a number of 160m mobiles with tall coils wound  on 10 inch forms plus a helical whip.. I guess they work.  I've used a helically wound fishing pole on 80m for fox hunting with my local club and it seems ok.

I may work on a helical system after getting some baseline data tonight with the straight whip (really 1" aluminium "antenna" pipe).  This was born out of a passing comment with XKA yesterday on a similar topic.  I would be interested in seeing how quickly the system improves with some top loading.  

Congrats the XXM Ken for hearing it twice on ground wave at the ragged edge of WSPR2 capabilities.  This might be a job for WSPR15.


SO far, the clear winner remains the 20m inverted vee with 25 feet of ladder line fed as a marconi.  Don't expect it to be unseated by the 102" antenna tonight but we will see.

73,

john XIQ



________________________________
 From: Edward R Cole <kl7uw at acsalaska.net>
To: John Langridge <jlangridge at sbcglobal.net>; "600mrg at w7ekb.com" <600mrg at w7ekb.com> 
Sent: Wednesday, January 22, 2014 4:18 PM
Subject: Re: [600MRG] WG2XIQ U3 Experiment - loading a 102" pipe on 630m
 

At 12:30 PM 1/22/2014, John Langridge wrote:
> Ladies and Gentlemen, for your listening pleasure, I will be running a 102" pipe fed against an existing radial system from my normal QTH.  The coil, as expected, was a huge challenge and needed a significant amount of additional series inductance to resonate.  The match is good for the moment and I am expecting no more than 5 mW ERP in WSPR2, 474.2 dial.
> 
> I fully expect this antenna to have some problem over night at some point but since its running from the home station, there may be something I can do.  Hopefully it will run all night and into tomorrow or until it catches fire, which is a real possibility.
> 
> 
> 73 and thanks for listening and submitting reports.
> 
> John WG2XIQ/KB5NJD
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> 600MRG at w7ekb.com
> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com

John,

102 inches = 8 -1/2 feet!  In meters = 2.6.  So the vertical is 2.6/157.5 = 1.7% of a full 1/4 wave.  Wow!

I wonder at this length whether it might make sense to wind a helical antenna to distribute the current more equally?  I guess one could calculate the diameter and number turns to be resonant and tap off a the ground end to match 50-ohms.

Suppose one wound on a 12-inch form by 10-foot; what could you use?  I guess what I am thinking about is a portable antenna/mobile antenna.  Ground plane is problematic.

Maybe a crazy idea?

73, Ed - KL7UW


73, Ed - KL7UW
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