Date: Sun, 04 Feb 01 07:10:10 -0800
Message-ID: <8179@gw.ab6qv.ampr.org>
From: yo2is@gw.ab6qv.ampr.org
To: rsgb_lf_group@blacksheep.org
Subject: LF: First OM <-> YO...on 137 KHz
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From: YO2IS
  Hello from KN05ps, am glad to report ( Rich, OM2TW already did it in the
DX-Clusters ) that the first ever VLF DX QSO was made from Romania, on the
3 feb at 06.30 when we ended the QRSS contact started at 06.00 with OM2TW
on 137.7 KHz. Was using the GRAM50 on my scrap 486DX50 with the mute on !
not listening the band only looking to the screen!. Got alerted by Rich on
the DX-Cluster that my signal was audible, put in hurry my headphones and 
was pleased to hear his normal CW with about 449 in the strong mains QRM. 
 Am realy happy that my three years of learning, building and dreaming LF
was not in vain. Thanks to all who did advice and help me, especialy to 
GW4ALG, G3YXM, ON7YD and OM2TW. TKS also for the stimulative 7S6SAQ and
7S6SAJ special VLF events cross band QSO's and their nice QSL cards.
 My obsolete rig is all home made: TX all tubes, differential VXO ECC82, 
EF184, EL84, 2 x GU50 (LS50) paralel, driving a Push-Pull 2 x GU13 (813)
GW4ALG design in class C, running 360 mA at 1600 V. Antenna a 41 m sloping
wire tunned with a 3.88 mH inductance ( three serial coils and a vario ) 
and a 50 / 130 Ohm matching trafo alowing a very good SWR, curent abt. 2A.
Take-off 320 to 045 deg. azimut. RX 137 KHz / 14 MHz XTAL converter with a
ua796 folowed by a 11 tubes double super, 500Hz mech. filter and L/C audio
filter. Receiving antenna 2m diameter 10 turn loop, rotated for minimal 
mains noise, at abt 360 azim (the wideband noise is centered on 136 KHz 
and can be lowered by 30 dB, the "cleaner spot" begins at 137.5 KHz) and
FET preamp with 10m coax cable down to the shack. The antenna is under 
the roof, at about 15m from three 10KV/380V power transformers and several
in/out underground cables. Grounding is the city central-heating network.
The rig is not ready "on the desk", its composed from 9 parts which have 
to be assambled / disassambled for every VLF tentative !.
 Am not an "exclusive LF" ham (have meet OM2TW on 2m and 160m either!) and
here is still a lot of work to detect/eliminate the mains noise problems
to be able to think about a future decent DX-VLF trafic from this downtown
location. 73 & DX, Szigy.