coden 7727TB

The formula to calculate wavelength is:

wavelength = speed of light/frequency

ie wavelength = 299,792,458 meters per second / 5110000 Hz

= 58.6678 metres

You would get by with a 5/8 wave antenna for a simple test so you need

Hi gunabat,
the good-enough formula for wavelength is
300/f where f is in megahertz

you will need a 1/4 wavelength so:
for 8020 you need 9.35 metres,
for 5110, you will need 14.68 metres

you should also connect the body of the radio to a good earth, or run a length of wire along the ground (a counterpoise). The length should be at least as long as the ones above. It doesn't need to make electrical contact with the ground - just be laying along it.

The 7727 was a good radio in its day. Just an expensive hassle if you have to fit out channels in it. If you got it at a good price and it has the VKS channels fitted, then that's all you need.

Gerry

The formula for calculating 1/4 wavelength horizontal HF longwire aerials is:

Length in meters = 71.49 divided by the frequency in Megahertz.

Gunabat - Others have given you the facts on length. It's worth mentioning that the end of the aerial wire remote from the transmitter must be well insulated and people kept clear of it. There can be high voltages there when transmitting and these can cause a nasty burn.

HTH

John

A lot of the above rings true to my observations - just a couple of points - a guru pointed out to me awhile back that a realistic calculation for long wires is a little different to pure high school physics re the speed of light - I was given 71.25 / frequency in MHz = a quarter wave wire for the frequency in question. Also, its best to elevate the far end of the wire if possible (in a tree etc ?) and broadside to the direction you want to send. If you can't elevate the wire, it can trail along the ground (strange but true) pointing to the direction you want to send. IF you had an extendable rod to support it, straight up is good too. As mentioned, don't touch the wire when TX'ing because energy levels can be high.

Thanks to all that replied. That is what I wanted to know I should have asked on the number one site in the first place. I'll know better next time thanks again.
Greg