[TowerTalk] perspective

[Ray LaRue]

Been at the business over 40 years.  Been lurking this list 
a long time to, but I gotta get into the fray with a possible 
resolution to the "1 db" question.  

It seems like all the hyperbole about 1 db making much 
difference, is easily settled.  

Those of you that are concerned enough with the truth 
of the matter, can prove the question for yourself, rather 
convincingly.  You can build a 1 db switchable, power, Pi type
attenuator.  

Operate your station with it over a period of time with 
and without the attenuator inserted between your exciter 
and your amplifier, (or your antenna direct, if no amplifier).  
You will be amazed how little effect it will have on your 
"contacts", at the weak signal or strong signal ends, of the 
spectrum.

Pi-attenuator formulas calculate 2- 828 ohm and one 5.7 ohm,  
will give you -1 db of loss.  Although the 828 ohm resistors 
calculate at 6 watts dissipation, with CW and SSB duty cycles, 
5 watt carbons will work fine with up to 100 watts drive, for 
short term tests..  

Select values you can find as close as possible to this.  I 
took some old carbon 5 watters that were near and filed them 
to the correct values.  Six ohms and 2- 828 ohm resistors 
will give you -1.05 db, close enough.  

A DPDT switch, 2 UHF connectors and a small box, completes 
the package.  Wire it with the switch to cut the pad combo in 
and out.  ee: When the switch is open the pad is engaged.  
When the switch is closed, the pad is excluded.

If you build it with short leads inside, in a small box, 
it should be good to at least 30 Mhz without a lot of 
stray reactance.  Make sure you use a decent DMM for 
the resistor checks.  (That will be at DC but it should be good 
enough for HF).  The instrument you use will effect your 
tolerances and thus the accuracy, of your tests.

Try several QSO's transmitting and receiving, with and without the 
attenuator in line.  I think you'll find it's real hard to 
justify worrying about the differences.  

For me, any DX station that is within a db or so of the noise, 
I don't  want to bother with.  I suspect also, if you're only a db 
or so, above the QRM to him, he won't bother with you either.  

Been there done that!

OK ya'll, the floor is yours.  Here is a way for possible resolution of
the question.  Get out you soldering irons...  Let's hear the results of
your actual tests.
73,
Ray LaRue, W4BYG, XT2AR 
A1-Op, BPL, PSA, ARRL life, past SCM Georgia
List Admin: aea-tempo, areu, azden, elmers, fieldday, flham, homebrew,
            kachina, morrow, test-equipment, tvi-rfi-emi @qth.net
VP Engineering, Dominion Video Satellite, Inc. (SkyAngel DBS)

--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com