VHF AM controversy

This Sunday's RSGB News contains a piece about AM operation on 145.8MHz in Scotland and alleges that some AM operators have been deliberately interfering with International Space Station communications on the same frequency. I do not know if this is true or not. If it is, then it should stop: there is no place for such behaviour in our fine hobby.

What I do know is that the RSGB has been EXTREMELY slow in publishing frequencies for VHF AM in the UK. Although people have been urging the RSGB to put an AM "centre of activity" or calling frequency in the band plans, this has still not happened, although a brief mention of 144.55MHz has been added in the footnotes a few months ago.

My recommendations are:

(1) All AM users in the UK migrate to 144.55MHz.
(2) AM operation on 145.8MHz should be phased out as soon as possible.
(3) Use of 145.8MHz for AM should be done with care to avoid any interference with ISS operations.
(4) The RSGB should publish 144.55MHz in the 2m bandplan as the agreed centre of activity for AM users.

AM is a great mode allowing simple homemade gear to make useful contacts. It would be a shame if AM users got a bad name as a result of this negative publicity.

VHF AM Yahoo group

This is a picture of G4BYE's version of my own Fredbox 2m AM transceiver design - a neat unit his is complete with proper PCB.

Many blog readers are already members of the Yahoo VHFam group. To join visit http://groups.yahoo.com/group/VHFam/ and follow the joining instructions.

At last VHF AM operation has got a mention in the latest UK VHF bandplans with the agreed "centre of AM activity" being notified in the footnotes as 144.55MHz. This spot in the European all-modes area is also used by some other users - I hear SSTV here sometimes - so it is NOT an exclusive spot, rather somewhere to look for 2m AM activity in the first instance. There's some AM activity on 145.8 still in Scotland but it would be good if users there would move to 144.55 so this became a UK-wide spot on which AM activity is likely to be found. Users can also be found on 70.26MHz on 4m.

VHF AM gear can be very simple to make and AM is an ideal mode for QRP building and experimenting. There's plenty of ex-PMR AM gear still to be found for next to nothing, ripe for use on 2m/4m AM.

2m AM now on the RSGB band plan

At last 2m AM gets a mention in the bandplan as published in the Feb 2009 edition of RadCom. Sadly not as the 144.55MHz "centre of activity" on the 2m chart, but rather as a comment in the footnotes.

Still this is better than nothing and people interested in 2m AM now know that 144.55MHz is the place of preference to centre AM operations. There is still interest in 2m AM as (a) simple gear is easy to build and (b) there is a lot of surplus ex-PMR AM gear around going for almost nothing. Also it is interesting to compare AM and FM as part of self-training.

It would be good if the AMers in GM-land would migrate off 145.8 down to 144.55 now so that all AM in the UK was on/around one common frequency.