[Dujon]

Barry,

Jerry is correct. I did some approximate calculations last night and came up with a difference of 6mm per leg of the dipole - depending on whether I used 186,000 miles per second or 300,000 Km per second as the speed of light. Both of these are approximations. Add in a little rounding of figures in my calculations and they are both 'near enough'.

You, in this case, are dealing with a free space wave length of around 20 metres. .006 of a metre will make no discernable difference to your reception (nor would, probably, a foot or 300mm to be honest). It's not as though you are trying to grab a narrow band signal - which you won't do with your receiver anyway, as it's designed as a broadband unit. So don't worry too much, and certainly not to millimetre accuracy, about the length of the dipole's legs. With what you are attempting I would consider 'close enough is good enough'.

Now, your receiver:

I am not familiar with the Kenwood unit you have to hand, but it appears that the various controls in your third picture, bottom row are as follows;

The group of four 'function' buttons - from the left

AM - this is amplitude modulation and is the same as the AM broadcast reception on a home radio. This method recognises the peaks and troughs of a signal in order to produce noise. It usually relies on the transmitting station sending a 'carrier' on which the modulation is imposed.

AM ANL - this looks like a noise limiting function. Most of these are set to take off (or filter) the short duration spikes of a received signal. If it works properly it will dampen such things as local power line interference and noise generated by such things as electric motors.

CW SSB - this mode is similar to AM but uses only part of the received signal. In effect it looks at a narrower band width than does AM and uses either lower or upper methods. I don't know which your unit uses as it doesn't stipulate. With what you are doing this probably doesn't matter. This, by the way, does not need the 'carrier' used by an AM transmitter.

FM BC - I'm assuming that this is FM (like the FM stations on your home radio). This, instead of using the amplitude of the signal to sort out the message, uses the change in frequency of a signal to produce the output you hear.

FM AFC - This is a guess, but I think this is simply a function enabling the radio to 'lock on' to an FM signal and, within reasonable parameters, keep the radio tuned to the signal being received.

Now the others:

It looks to me as though the RF marker is designed to generate a low level signal (internally) to enable calibration of the frequency dials. I am wide open to correction on this one.

The band selector, I would think, is reasonably self explanatory.

The antenna (aerial) trimmer is provided to 'peak' received signals. This is very handy when using the same piece of wire for various signals. It's a crude, but effective, matching unit.

AF - this is simply the audio frequency gain control - what most of us call a volume knob.

I hope that lot helps.

Ah, yes, the dual tuning drums.

Again I must emphasise that I am not familiar with this receiver.

The drums though could be a coarse tuner (the top one) and what is sometimes called a 'band spread' tuner (the bottom one). This enables you to set the upper drum to the frequency you are after and then fine tune using the lower one.

*edit*

I should add that I'm not too sure what you are going to gain out of the exercise. Have fun anyway.