An Introduction to 4m - Part 1

An Introduction to 4m - Part 2

An Introduction to 4m - Part 1 of 2

A bit about four metres

The 4m band, once activated only by a few G stations, Gibraltar, Cyprus and a few other countries, is now a band with increasing activity. Many European countries are now licenced for 4m. Some ready-made equipment covers 4m: ex-PMR for FM, a handful of commercial transceivers for SSB/CW, and transverters to add on to HF radios. Antenna manufacturers sell antennas with a range of gain and size. Many 4m operators have built their own equipment and there's a good community of knowledge.

In this short introduction, we cover what you might find on 4m, how you could get started, plus some links to help with further searches.

• The Four Metres Website contains a wealth of information, including up-to-date information on countries with a 4m allocation.

• Wikipedia has an entry about 4m.

• Yahoo has a Group dedicated to 4m.

We have no connection with any commercial companies or products mentioned. If we omit someone’s product this is an oversight on our part and not an implied criticism.

Operating and Propagation

Several modes of operation are in regular use on 4m, FM and SSB/CW being the most popular:

FM is popular for local operating, and occasional DX via sporadic E propagation. Currently, 12.5kHz-spaced channels are allocated in the band plan between 70.3 and 70.5 MHz. The FM calling channel is 70.450MHz, and 70.425, 70.475 and 70.400MHz are the most popular frequencies for simplex working.

Look for an FM net in your area. FPARC’s own G3XUX runs a net on 70.325MHz on Sunday mornings starting at 0900 clock time. He is usually located near the summit of Hampshire “mountain”, Butser Hill (locator IO90MX) and is joined by stations from Bournemouth to Bognor Regis and from the Isle of Wight to Wales. Other nets in the south of England that we are aware of include:

• G0AYZ (Wednesday 0900 clock time 70.325MHz)
• G0UZL in Dorset for the Blackmore Vale ARS (Wednesday 2030 clock time 70.475MHz)
• G8ROG in Reading (Sunday 0930 clock time 70.425MHz after RSGB News)

The nets are friendly gatherings and are ideal places to get reports on the effectiveness of your equipment and antennas.

There are no repeaters in the 4m band!! Instead, you may come across a “parrot” which records incoming FM signals and then replays them over the air. Note: CTCSS tones are sometimes required. The following parrots have been active at some time:

• MB7FM in Tring
• MB7PA in Louth, Lincolnshire
• MB7PB in Ludlow, Shropshire
• A DX parrot has recently started at ON0ABT

SSB and CW activity is centred on the calling frequency 70.200MHz and is highest during contests and during the Sporadic E propagation season. Horizontal polarisation is the standard. You can make contacts using most of the normal methods available for VHF.
Abnormal tropospheric conditions and sporadic E (Es) ionisation are the most common ones. Es occurs mainly during the summer months June and July, and sometimes also in December.
Dramatic DX can be worked with modest equipment and dipole antennas.

• G0MJW has a website which gives some background to the mechanisms thought to be behind Es

• Beaconspot has a useful map displaying several beacons in the UK and in continental Europe.

The previously mentioned Four Metres Website has a useful list in their "DX Survival Guide” which can be found on their website in the second page under the Operating tab.

4m DX contacts are reported on the cluster networks.

• DX Maps often shows Sporadic E contacts in near real time, and also estimates the MUF (maximum usable frequency), so it’s a good source of information about current Es. It will even email you with notifications. Here's an example map from dxmaps.

A few contests take place on 4m, mostly run by the RSGB:

• 1st and 2nd contests, on a Sunday usually in April and September
• Trophy contest on a July Sunday
• UK Activity contests on the 5th Tuesday in a month

A typical map of contacts made by FPARC members during the Trophy contest in 2014 is shown below right:

Auroral reflection, meteor scatter and digital mode QSOs also take place on 4m.

• OZ2M has a website with some useful information.

The first EME (earth-moon-earth) QSO on 4m was made between GD0TEP and ZS6WAB in 2009

This article continues with An Introduction to 4m - Part 2

Page content by Chris G3WIE and Ted G3XUX gratefully acknowledged.