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G3WCB England flag England

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Hi, I've had my call-sign since 1967, and have mainly been active on the LF bands and VHF. Professionally I have worked for the UK Department of Science and Industry, British Airways, INMARSAT, and most recently a large multinational Aerospace company, Thales Avionics. One of my main amateur radio interests is on LF/137 kHz, and MF/630m. I operate QRSS, CW and WSPR on these bands.

The LF station comprises a MOSFET PA running 150W RF out, and an ICOM PCR-1000 rx with G3YXM fet pre-amp. The antenna is a 20m inverted-L at 6m, but I'm always tinkering with it to improve the performance!

I've included a few pictures of my 137 kHz equipment, including two examples of a 136 kHz low pass filter.

The MF station runs 30W RF out from a MOSFET Class-E PA, and for WSPR the PA is driven by a QRSS Labs "Ultimate 2" Beacon TX. There are some pictures of my 475 kHz equipment below.

I'm also active on 6m, 2m and 70cm, particularily during UK Activity Contests in support of the Drowned Rats Radio Group.

I'm a member of the Radio Society of Harrow, G3EFX, and the Drowned Rats Radio Group, M0HRF. I currently hold NOV for the INMARSAT Club station, G4SAT.

Until Easter 2015, I lived in a village called Iver, which is about 5km north of London Heathrow airport, and just outside the M25 motorway. Whilst I do still occasionally operate from the Iver location (IO91RM), following retirement the main station was located for a while in Moreleigh,IO80DI, which is near Totnes in Devon. The current, hopefully permanent, QTH is located in Dartmouth, Devon, IO80EI. The Dartmouth QTH is poorly situated for VHF except for a narrow "squint" to the East, but there is a hill nearby (Firebeacon Hill) with a good take-off to the South and East, and I regularily operate /P from this location (IO80EJ)

QSL via RSGB bureau or direct.

73, Dave G3WCB


15 Nov 2014

14 May 2015

200 watt 137 kHz Low pass filter, using T-200 toroids. It has an RF voltmeter, and a small fan that is controlled by the PTT line

200W 137 LPF with RF Voltmeter and cooling fan. It uses T-200 toroids and polypropylene capacitors.


The polypropylene capacitors have a habit of going open circuit, so they are mounted on screw terminals for a quick change!


This is an earlier version of the 137 kHz LPF. It uses a mixture of toroidal and air-cored inductors. The capacitors are RF mica types, which are better than polypropylene types, but much harder to find.




475 kHz loading coil in garage

475 kHz loading coil in garage at Iver.


475 kHz vertical antenna

475 kHz vertical with capacity hat attached to garage.

The chicken weathercock isn't part of the antenna!


U2 internal view

QRSS Labs "Ultimate 2" beacon TX kit built into re-purposed enclosure.


U2 another internal view

QRSS Labs "Ultimate 2" beacon TX internal view.


portable operation on 70cm from IO80di - on a nice day!    

Portable operation on 70cm from IO80di - on a nice day!

The mast is three sections of Wickes 25mm diameter aluminium TV mast, and is mounted in a "drive over" plate. The mast is self-supporting in calm conditions, but can be guyed if necessary. I've since found out that B&Q sell 32mm diameter TV masts, which would be a bit more rigid.


7340849 Last modified: 2016-05-26 21:35:21, 4845 bytes

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