QFH vs Turnstile

[Grumps]

Hi
This is probably not the ideal NG to post to, but you're all
knowledgable radio enthusiasts.

So, considering complexity of build, size and amount of material used,
which is the better antenna for 137MHz NOAA reception?

Ta.

[David Taylor]

The QFH is preferable as it has the correct polarisation (right-hand
circular) and the better polar diagram (more gain towards the horizon
where you need it). A Turnstile is simpler. I'm not a metalworker at
all, but I did enjoy getting some copper pipe, right-angle joints, and
using a blowtorch to solder it all together!

https://www.satsignal.eu/wxsat/equipment.htm

--
73,
David GM8ARV
Web: http://www.satsignal.eu

[Brian Howie]

On 31/05/2019 22:15, Grumps wrote:

There are some comparisons om GM8ARV's website.

https://www.satsignal.eu/wxsat/equipment.htm

Brian

--
Brian

[Grumps]

Thanks both.
Did you have any issues with the plastic pipe whilst you were soldering
the elbows? That is, did the pipe melt?

[David Taylor]

On 02/06/2019 09:16, Grumps wrote:
[]

> Thanks both.
> Did you have any issues with the plastic pipe whilst you were soldering
> the elbows? That is, did the pipe melt?

Not that I recall, no. I guess you could put a damp cloth near the
plastic pipe if needed. The soldering process is quite quick as the
bends are pre-supplied with solder.

I hope this is all correct as it must have been getting on for 20 years ago!

--
Cheers,
David
Web: http://www.satsignal.eu

[Grumps]

On 02/06/2019 15:47, David Taylor wrote:
> On 02/06/2019 09:16, Grumps wrote:
> []
>> Thanks both.
>> Did you have any issues with the plastic pipe whilst you were
>> soldering the elbows? That is, did the pipe melt?
>
> Not that I recall, no.  I guess you could put a damp cloth near the
> plastic pipe if needed.  The soldering process is quite quick as the
> bends are pre-supplied with solder.
>
> I hope this is all correct as it must have been getting on for 20 years
> ago!

Thanks.
I've done a fair bit of soldering with 15mm and 22mm pipe (both solder
ring and end feed). I'm sure that 8mm will solder very quickly, and
solder ring elbows quicker than end feed. And the wet rag will be a
belt'n'braces measure.

[Brian Reay]

On 01/06/2019 07:15, David Taylor wrote:

As per David's comments, if you can make a QFH that is the way to go but
they are a 'faff' and, if, as happened to mine, the mast topples, (in my
case when lowering it), impossible to salvage.

I'd rather assumed the dimensions of a QFH were supercritical but checks
with a return loss bridge indicated otherwise (I'd expect a 'sharp'
response if the dimensions were critical, the response was quite broad-
from memory over 5 MHz.

A turnstile (with a matching 'cross' under the main elements) is far
easier to make and I've had good results from one in the past.
Certainly, if you are a beginner, I'd recommend making one and seeing
how you get on. You may well find, provided you have good location etc,
you get adequate reception for your needs.

[Grumps]

On 02/06/2019 15:47, David Taylor wrote:

> On 02/06/2019 09:16, Grumps wrote:
> []
>> Thanks both.
>> Did you have any issues with the plastic pipe whilst you were
>> soldering the elbows? That is, did the pipe melt?
>
> Not that I recall, no.  I guess you could put a damp cloth near the
> plastic pipe if needed.  The soldering process is quite quick as the
> bends are pre-supplied with solder.
>
> I hope this is all correct as it must have been getting on for 20 years
> ago!

Thanks all.
I have decided to make a QFH as per various online instructions and a 3D
model.

This is from the 3D model (where the little pipes join):
https://flic.kr/p/2gasSNg

These are my pipes, all cut to length:
https://flic.kr/p/2gathhz

But can you do this instead:
https://flic.kr/p/2gasSKW

I know it'd be impossible to solder these elbows withing the PVC pipe,
bit I could solder on the bench and cut slots in the PVC, and then glue
a cap on the end.