Tag Archives: IC7100

RSGB AFS Phone Contest

On Saturday 16th January George M1GEO, Chris G8OCV and Dave M0TAZ took part in the RSGB AFS phone contest. The idea was to give the Secret Nuclear Bunker Contest Groups first outing of the clubs call MX0SNB. The clubs contest site benefits from having a large doublet antenna (40m per leg) 30m up on the large onsite mast.

Using the Icom 7100 and 100w we noticed quickly while it was possible to match the antenna it didn’t seem to be working very effectively.  The shack is located 20m below ground, in the original Home Office radio room. Once inside the bunker you have no idea what may have occurred. We decided to go back up to the mast and check, and on taking the doublet down we discovered one of the 300 Ohm feeder legs had become detached.

The antenna is located close to 30m above the ground, and the mast is already very well elevated, making it sometimes hard to maintain a working HF antenna in the winter weather. A quick fix later and we was soon back on the air.

George M1GEO

We operated from 3 till 5 PM and managed to work over 100 stations. The contest was well supported with many club stations and members from around the country. It was just a casual entry, but enabled us to get our club call on the air. Thanks to everyone we worked. 73 MX0SNB

50/70/144/432MHz Christmas Cumulatives

The RSGB 50/70/144/432MHz Christmas Cumulatives Contest series run from the 26th to the 29th of December each year and are intended as a bit of fun in the contester’s calendar.  The contest exchange is the usual RS(T), Serial Number and 6 character locator (e.g. JO01DQ).  These contests are really easy to become involved in, and often provide a good excuse to escape the house after Christmas.

This year, Dave M0TAZ, Dave M0YOL and George M1GEO decided to operate alfresco from the Bunker for the final two days (George having put in token entries on the 26th and 27th for 144 MHz from Home).  We operated on 50 MHz, 70 MHz and 144 MHz for the full 2 hours on a picnic table, in large overcoats on cold winter afternoons, packing up in the dark!


144 MHz was to be our main band. For that we used an Icom IC7100 transceiver, DG-8 masthead-preamplifier (GM3SEK design/M1GEO construction), and 9-element tonna (10m AGL), powered from a large 60 Ah sealed lead acid battery.


50 MHz and 70 MHz were run as a sub station. Again, using an Icom IC7100 transceiver and an InnovAntennas 6-element dual band (50/70MHz) yagi (7m AGL), with an 85 Ah leisure battery. The battery also provided mains power via a small inverter, which charged the logging laptops.


The table below shows the number of QSOs made per band on each day, as well as the best DX station callsign, locator and distance. In order of fairness, we switched callsigns on the second day, all points awarded to the SNBCG.

Band  Info 28 Dec 2015 (M0TAZ/p) 29 Dec 2015 (M1GEO/p)
144 MHz # QSOs 30 40
(IO64XL 525km)
(IO74PC 430km)
70 MHz # QSOs 7 10
(IO81MX 226km)
(IO92XW 141km)
50 MHz # QSOs 8 13
(IO81KQ 236km)
(IO74PC 430km)

The map below (click to zoom) shows the worked locators for the Contest. Almost all of the DX was worked on 144 MHz. Produced by OpenContest’s EDI Visualiser.


A very enjoyable activation.  Even if it was a little cold! Lots more photographs here.