[UK-CONTEST] Antenna height on 70cms

[Callum MØMCX]

>> you should easily become a multi millionaire overnight!

Firstly, thanks for the encouragement, I am indeed, not short of a few bob.
An amazing insight you have.

Secondly, I conducted a "real-world" test - so either I make all this crap
up or I'm completely mad. 

You decide.


Callum McCormick
http://www.m0mcx.co.uk/ 
Yahoo Groups:
- http://groups.yahoo.com/group/rsgb/
- http://groups.yahoo.com/group/narrowboats/
- http://groups.yahoo.com/group/nordhavndreamers/
t: 07976 631881
65 Glendon Way, B93 8SY


-----Original Message-----
From: David Barber [mailto:david.barber at dbelectronics.co.uk] 
Sent: 01 July 2009 19:38
To: 'Callum MØMCX'
Subject: RE: [UK-CONTEST] Antenna height on 70cms

Hi Callum

That is an astonishing difference!

For the figures quoted @ 432MHZ

25m WE103 = loss 1.88dB

30m Eco15 = loss 1.83dB

So a theoretical feeder difference in your setup of 0.05dB.

Now as an owner of a TS2000 I know the S-Meter on FM is a farce but for a
moment lets take it as being correct and an S point = 6dB increase so your 6
S point increase would indicate a signal level difference of 36dB at the
radio.

That really stretches the imagination and if correct you should easily
become a multi millionaire overnight!

:-)

Regards

David
G8OQW


-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Callum MØMCX
Sent: 01 July 2009 19:03
To: uk-contest at contesting.com
Subject: Re: [UK-CONTEST] Antenna height on 70cms

Two facts to bear in mind.

1) Henry quoted me losses for Westflex at 70cms as 7.5db per 100 meters.
Your losses may be a lot greater than advertised by James. I would be
tempted to go for a 5m pole with a 10m coax run if I had to. The real world
difference, assuming good take-off  at a good site between the two is hardly
measurable.

2) Last month, I conducted a real-world test comparing of 25 meters of
Westflex at 70cms -vs- 30 meters of Ecoflex 15. The difference between the
two was staggering. A local station on the Westflex at S1 became S7 on the
EcoFlex 15 using a TS2000 on FM. White dusty noise on the Westflex was fully
quietening on the EcoFlex. My TX signal also shot up.

In contrast, the differences at 144mhz was pretty negligible (an S point or
so) which led me personally to believe that using Westflex for anything over
2m was a waste of time.

EcoFlex 15 is *only* £5.80 per meter (!) currently with matching N-Types at
£10 a throw. So an expensive hobby for some.


Callum McCormick
http://www.m0mcx.co.uk/ 
Yahoo Groups:
- http://groups.yahoo.com/group/rsgb/
- http://groups.yahoo.com/group/narrowboats/
- http://groups.yahoo.com/group/nordhavndreamers/
t: 07976 631881
65 Glendon Way, B93 8SY


-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Ray James
Sent: 01 July 2009 12:27
To: UK-Contest; MM0BQI
Subject: Re: [UK-CONTEST] Antenna height on 70cms




--- On Wed, 1/7/09, MM0BQI <MM0BQI at blueyonder.co.uk> wrote:

> I have two options for mounting my
> 18ele 70cms antenna this weekend.  Site is on the
> highest point of a rounded hill with reasonably clear take
> off.
> 1.  5m above ground with a 10m run of Wesflex
> 2.  10m above ground with 20m of Westflex
> Does the additional height cancel out the feeder losses or
> is higher always better?
> Thanks
> Jim,  MM0BQI

Hi Jim,
You're only adding an additional approximate .375db of loss at the greater
height so that's what I would run with to get the antenna that bit clearer
of the ground. If it's only a "reasonably clear take off" then height will
be more important for directions that are not optimal.

73 Ray GM4CXM



      
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