[GreenKeys] On PVC poles

[Bob kb8tq]

Hi

What frequency(s) is the antenna targeted at? For < 30 MHz, just about anything 
that is “plastic” will be reasonably low loss. Consider that a lot of people have 
trapped antennas with trap Q’s around 10 to 20. They seem to work fine. 

If you are building something for UHF then indeed the “microwave test” makes
a lot of sense. 

=====

When you do the “coil” part of the helical, turn spacing is one of the variables. 
You may find that a wide spaced coil works better than a close wound one.

Bob

> On Jul 16, 2020, at 11:50 PM, Dave Horsfall <dave at horsfall.org> wrote:
> 
> (Somewhat on topic, as I did use "glass" RTTY[*] some years ago, and am trying to find room for a real one).
> 
> I have a need to make a helical (easily concealed etc), but I am somewhat baffled by "common knowledge" so I figured that this list is the best resource :-)  A magnetic loop is too directional for my tastes, as is also far too high-Q i.e. needs to be re-tuned if you shift by a just a few kHz.
> 
> Metal is obviously right out, and I understand so is wood (because of its water content), so I thought about a length of PVC pipe with the helical wound around it.
> 
> Now, herein lies the tale...
> 
> Apparently PVC pipe may or may not contain carbon, and the only way to find out (apart from deciphering the manufacturer's code) is to place piece of it inside a microwave oven (with the wife not looking) with a glass of water to act as a dummy load to protect the magnetron.
> 
> If the PVC is warm, it contains carbon and is therefore unsuitable...
> 
> So, what is the veracity of this claim?
> 
> [*]
> And yes, I know about the CR/LF problem, as with 72 columns.
> 
> -- Dave VK2KFU
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
> 
>>>> Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
>>>> 2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
>>>> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to kb8tq at n1k.org