[Lowfer] Coil Forms at 1750-Meters

[Howell, Laurence (Shanghai/Singapore)]

Ive got a free running stable vfo with a open coil using an "air type"
former. For a rough and ready check of the net impact of any material to
be used as a former or whatever I offer up a piece of the material near
the coil and using an SSB receiver see how much the frequency changes. 

Offering it up and what you hold it with has to be considered of course
but doing this has made the choice of formers from cheap materials to
hand here in Asia easier. Ive ended up using hard clear Plastic tubular
small round shampoo bottles and drilled out vertical lines down the
length to retain the round shape but make it a mix of air and
plastic....

The less net effect or freq/amp change the better the choice (for this
freq range) It quickly became evident of the massive variation in what
plastics/polymers must have in them and the net effect therein.

Laurence 3D2KL



-----Original Message-----
From: lowfer-bounces at mailman.qth.net
[mailto:lowfer-bounces at mailman.qth.net] On Behalf Of Ed Phillips
Sent: Friday, September 19, 2008 7:34 AM
To: Discussion of the Lowfer (US, European, & UK) and MedFer bands
Subject: Re: [Lowfer] Coil Forms at 1750-Meters

Hi All,

I know from articles that I've read in the past that black PVC plastic
plumber's tubing is a poor choice for antenna trap coil forms at
HF...but how does it rate for 160-190-KHz...?

The goal here is to wind my own RF tank coil / antenna link for a HB
tube-type transmitter for that band, & I'm wondering what I might come
to expect in terms of losses, performance, etc. BEFORE I start cranking
wire...! Hi Hi

Any & all comments based upon real-world experiences are solicited and
welcomed! Thanks in advance...

~73~ Eddy VE3CUI - VE3XZ"

	All depends on the particular black PVC - some is lossy and some
is not but probably none so lossy as to be useless.  Grey and white are
better and make neat looking coil forms.

Ed


_______________________________________________
>From the Lowfer mailing list
Send messages to: Lowfer at mailman.qth.net
To sub/unsub visit: http://mailman.qth.net/mailman/listinfo/lowfer