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DJ7ST > QRP 23.05.03 09:05l 55 Lines 2456 Bytes #999 (10) @ EU
BID : HFAZ93DB0ABZ
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Subj: QRP-MINIMAL-ART-SESSION
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From: DJ7ST @ DB0ABZ.#NDS.DEU.EU (Hartmut)
To: QRP @ EU
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From: DJ7ST@DB0ABZ.#NDS.DEU.EU
QRP-CONTEST-COMMUNITY (qrpcc) 22-Mai-2003
c/o Dr.Hartmut Weber, DJ7ST
Dear QRP and homebrew friends,
in one week, at Ascension Day the 4th QRP-MINIMAL-ART-SESSION will
take place. There's still time to complete simple projects. Like e.g.
the "Michigan Mighty Mite" featured in SPRAT #105, a basic single-
stage crystal controlled solid state tx.
The complete QRP-MAS rules and a list of suitable circuits have
been posted to the packet radio network some weeks ago. (Search by
entering "C < DJ7ST").
Caveat constructor! Doing it with (almost) nothing is an art.
A simple tx producing a immaculate signal when connected to a dummy
load, may show ugly reactions when confronted with braid currents
and a mismatched antenna, resulting in chirps and worse.
When using a simple tx an additional antenna matching circuit, e.g.
a pi filter, is highly recommended, especially as it doesn't add to
the component tally. When not completely mis-dimensioned, the additional
losses will be negligible. It may even prove to be an advantage. The
"Piccolino" I built became more efficient with a pi filter added.
Apparently I used a less than optimum Q for the tank circuit, and
the pi filter matched "backwards".
So please test the miniscule tx connected to an antenna, with the
rx antenna disconnected or the rx input terminal grounded.
The QRP-MAS, during which no serial numbers are exchanged, thus is no
real contest, meaning we are free to use 3560-3580kHz. Expect MAS signals
between 3576 and 3579 from operators who knitted a simple tx around a
3579kHz (the experimenters' frequency) low-cost crystal. We shouldn't
disappoint them.
So please don't forget to monitor frequencies above 3560kHz, especially
3575-3580kHz.
And a tip how to "beat it to zero". Even a crystal controlled tx may
exhibit considerable retroaction when tuned to zero beat without its
final amplifier connected. Better results are obtained by tuning the
complete tx with full power transmitted into a dummy load. Then the
frequency will stay put. Power levels around 1w will not even overdrive
the rx when you disconnect its antenna.
BCNU in the QRP-Minimal-Art-Session on the evening of Ascension Day.
73/2 "Hal", Hartmut, DJ7ST (once again tks to Eddi, DK3UZ, for translation)
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