[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
Power 10w (in shack)
10 db cable loss (~50' 1/2" heliax)
Power at antenna 1w
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.
>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. :)
>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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