[VHFcontesting] uWave Contest Rules Question

kr7o at vhfdx.com kr7o at vhfdx.com
Thu Aug 10 18:08:44 EDT 2006

I may regret stepping into this one.  First off, this clearly shows the 
problem with entry classes based on output power.  ERP is a much more 
equitable (uh-oh, here it comes) evaluation of station performance than 
output power.  While 10W may be QRP at VHF/UHF it definitely isn't at 10GHz 
and most microwave bands.  Likewise, 10W into W5UN's MBA is not QRP 
either.  Since ERP includes all external system gains/losses it is also a 
fair indication of RX performance (neglecting the performance advantage of 
mast mount preamps).  ERP is not that difficult to calculate and if a 
operator has done their required RF exposure calculations, one should be 
capable of performing ERP calculations.

Now, since most contest sponsors aren't on board with ERP based entry 
classes, things become interesting.  As Ev states, output power is 
"Traditionally, ... measured at the final
output stage of your station."  I haven't reviewed recent interpretations 
of the FCC rules, but I would expect this is still their standard also (and 
is my basis for operations).  This is all fine and good at HF and lower 
VHF, where minimal cable loss is somewhat trivial (except for those with 
big towers far from the shack).  But consider the following scenarios 

Station 1
Band 10GHz
Power 10w (in shack)
10 db cable loss (~50' 1/2" heliax)
Power at antenna 1w

Station 2
Band 10GHz
Power 10w (preamp and/or transverter + power amp mounted at antenna)
negligible cable loss (1' of 1/2" superflex)
Power at antenna 10w

ERP differential = 10db.  Power needed (in shack) for Station 1 to have the 
same transmit signal as Station 2 = 100w.  So which station will win the 
contest (all other things being equal)?

So in the case of Station 2, power output is (effectively) measured at the 
antenna.  The station setup for Station 2 is not uncommon and legal within 
FCC and all contest rules, so this does indicate a situation where power 
can be measured at the antenna.  If the desire of contest sponsors were to 
make their rules more equitable (here we go again), power should be 
specified at the antenna.

If you desire to have a competitive station and remain beyond reproach with 
the rules auditors, build to Station 2 standards, barring an explicit 
clarification from the contest sponsors.
Contests (expecially VHF+) will never be equitable, so just get on, do your 
best, and have fun!

At 06:53 PM 8/9/2006 -0700, Radiosporting Fan wrote:
> > If I have a small amplifier  brick in my 902 MHz
> > transverter putting out 20 watts PEP, and a
> > measured 4 dB worth of relay, connector, and coax
> > cable attenuation between it and the antenna, what
> > class am I in and why.
>Hi Keith,
>For the record, my opinion and $0.99 gets you a "Big
>Gulp" at the corner mini-market.  Here it is...
>Taking a close look at the ARRL rules for VHF
>contests, you'll notice that they *never* reference
>ERP.  On the other hand, they do reference the term
>"Power Output" twice (Rules 1.15, 2.2.1).
>Traditionally, this is the power measured at the final
>output stage of your station.
>I do not work for the ARRL, adjudicate for the ARRL,
>check logs for the ARRL.  I am happy, however, to
>drink a Gig Gulp between contest CQ's. :)
>Ev, W2EV
>Do You Yahoo!?
>Tired of spam?  Yahoo! Mail has the best spam protection around
>VHFcontesting mailing list
>VHFcontesting at contesting.com

73, Robert KR7O/YB2ARO, DM07ba/OI52ee  (ex.  N7STU)
kr7o at vhfdx.com

www.vhfdx.com (KR7O/YB2ARO homepages)

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