[Antennas] Diminishing Returns

[Chris Boone]

-----Original Message-----
I guess I'll have to chime in as I was the instigator of the project
KA4INM refers to.

Tony W4TAS was the builder of the HF to 440mhz linear translator.  He
did an excellent job in designing and building it.  The first stage was
a passive mixer with a good high level of injection.  

We checked it thoroughly for it's noise floor, compression limits and
linearity within the designed input operating range.  It had less than 1
db variation at all expected operating inputs/outputs.  Within the same
narrow frequency and input range, it was very accurate.  This was
considered more than sufficient, for our intended purposes.  

It allowed: unattended remote operation of the sense antenna,
translator, etc. and all interested parties to be at one test site where
a reference transmitter, etc. and the Tektronix 2710 SA were located.
The microprocessor in the 2710 did the signal calculations for us.

We spent the entire day testing a number of vertical fixed and mobile
antennas on 40 and 20 meters.  We did it mainly for the benefit of those
who participated, but did not intend to publish the results.  We who
were there did not consider it a "waste of time".  All thoroughly
enjoyed and learned from the exercise. 

I still have the original data and translator.  The translator performed
so well, I will use it again.  

Anyone can attempt the same thing with their own set of criteria and
equipments.  But please don't knock someone else's efforts to gain new
insights and understandings, into the antenna sciences.

Raymond LaRue
Vice President, Broadcast Engineering
SkyAngel US, LLC
3001 Keith Street, NW
Cleveland, TN 37312

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Interesting project...and I applaud the effort...but then:

A spectrum analyzer 1000ft away was easier, faster and more reliable,; I
understand your reasons but even so,
the HF to 440 translator:
1) required an IDER on the output (did it have one?) no matter what the
power output, it is an intentional radiator in the ham bands
2) the unit could NOT be overloaded or else the output would be overdriven
and not linear...thus skewing the results of the UHF signal...kinda hard to
do without a GREAT AGC..
3) The cost of designing and building one was probably more than what the
price of a good spectrum analyzer (Even rented!) would be...just having one
person at the analyzer take readings would be faster and much more accurate.

Just my $0.02...

Chris
WB5ITT
Former Chief KDMX/KEGL/1190 Cheap...eerrrr Clear Channel, Dallas
Also former Contract Engineer, KSBJ Humble/Houston 2004 (ring a bell?)
SBE member for 30years (on and off)
Was Asst Chief Engineer of KLVI 560kHz 5KW DA-N, Beaumont TX at age 17....we
rebuilt the phasor and networks on the 4 towers (only 66deg tall) before I
left and got rid of the 3 wire open line and went to 7/8in Heliax to
stabilize the array. Number 1 tower btw STILL has a Negative Impedance (not
reactance!) at night and is the omni during the day...Been there, got the T
Shirt..