Before we were allowed on 5mHz, I heard a chap talking about it on 40 metres. He said that he'd applied for his NOV and intended to "coordinate five meg activity". I believe that too many people have tried to do this, resulting in so many big brother issues that people have been frightened off.

We are being monitored, you must use the SINPO method of reporting signals, you must send in your log sheets, you mustn't do this, you must do that, you have to carry out aerial experiments... It's no wonder that people have run away. I'm now back on 5 megs with an 88 foot doublet at 25 feet above ground fed with 300 ohm twin. And it works very well. So, what is the five megs experiment all about? Read on...

NVIS

NVIS stands for, Near Vertical Incidence Skywave. Basically, this means firing your radio signal straight up to the ionosphere where it is reflected and comes more or less straight back down. What's the point? The idea is that, in jungle or mountainous terrain, you can get your signal over obstacles to the receiving station. Straight up, and straight back down the other side of the mountain. See the diagram below.

VHF and UHF signals won't go through the mountain or bounce off the ionosphere. The only way to contact the receiving station on the far side on the mountain is to use NVIS. Horizontat dipoles, as low as five feet above the ground, are ideal for high angle radiation.

The MUF, maximum usable frequency, is the highest radio frequency which can be successfully reflected off of the ionosphere at a given time. Obviously, it is important to know the MUF when using NVIS.

When working across town on 40 metres, there are two factors to consider. Is your ground wave reaching the other station? Is your Near Vertical Incidence Skywave reaching the other station? In reality, the station on the other side of town is probably receiving a combination of both.

When testing your new 40 metre dipole, don't try contacting your mate a few miles away. The chances are that he won't hear you. Or, at the very least, your signal will be weak with him. On 80 metres, the chances are that your ground wave will travel further and your skywave will come straight back down from the ionosphere. QSB and strange phasing effects can be troublesome when working stations a few miles away.

I often monitor RAF Volmet on 5450kHz. This makes a good beacon station as they're on twenty-four hours a day. The computer generated female voice can get somewhat boring at times, but it's a good indication as to conditions on five megs. Actually, I have heard that the female is in fact a blow-up doll. ???###!!!

CCF... The combined cadet force

What happened to the CCF boys? They used to come on five megs during the school dinner hour and after school later in the afternoons. There were 19 sets fired up all over the country, and now there's nothing. Delta Oscar and Tango Golf were two channels I often monitored. I used to have some fun with one five alpha, the call sign of a college close to my QTH. And some of the naughty schoolboys would fire up on 6.6mHz. Good grief, perish the thought!

THE SINPO CODE

	1	2	3	4	5
Signal	S1 to 2	S3 to 4	S5 to 6	S7 to 8	S9 or over
QRM	S9 or over	S7 to 8	S5 to 6	S3 to 4	S1 to 2
QRN	S9 or over	S7 to 8	S5 to 6	S3 to 4	S1 to 2
QSB	> 6 S points	6 S points	4 to 5 S points	2 S points	NO QSB
Overall	Difficult	Poor	Medium	Good	Excellent