[TowerTalk] Hygain to OWA

[Jim Thomson]

Date: Wed, 18 Feb 2015 06:15:29 -0500
From: "Ed Sawyer" <sawyered at earthlink.net>
To: <towertalk at contesting.com>
Subject: Re: [TowerTalk] Hygain to OWA

###  Did u put a wattmeter at the top of the 80 foot tower, and see how much
power u have there,  with say exactly 100w applied in the shack ?   IE, measure
the loss of the coax  to each yagi.   I have seen several cases where that was done,
with 10m yagi at the top of a tall tower, and the loss was incredible.   In one case,
with 1 kw applied in the shack, only 375 watts measured at the top of the 100 ft tower. 
That was a total run of 300 ft of RG-8U.   It was replaced with .875 inch heliax.  Then
over 900w was measured at the top of the tower.   It was like apples and oranges.

## How many db per S unit on your xcvr on 10M ?  My yaesu is like 4.5 to 5 db
between S8 and S9.... but drops way off below that, like 2 db per S unit. Shut the
agc off in the RX, and then back the RF gain way down.  Then the differences
in audio level, between the two ants is easily measured with any audio test gear. 

##  My buddys Icom, with all its pre-amps turned on, is 7 microvolts for S-9  !! 
I would not be using xcvrs S meter for some kind of meaningful measuring device.  

Jim  VE7RF
   


The 4el yagi is on top of the tower at 80 ft.  The 8 el yagi is at 30ft
fixed to EU.  So yes, there is sometimes some angle optimization that would
explain the larger than expected gain difference.  But it ALWAYS beats the 4
el yagi.  And not having an antenna range available, it's a good sanity
check that the antenna is performing to see always 1 and sometimes 2 S units
of improvement.

 

HFTA says that the 30 ft position should add 6 - 8 dB at its peak to Europe
but often its equal to or a few dB less than the top position.  I have never
seen the 8 el less than an S unit louder than the 4 el.

 

Ed