AM radio mod for 40 and 80 M

[pasha]

Hello i am wondering if anyone has ever tried modding an am radio for use in the ham bands. the things that should be done, i think, would be adding external antenna support, and changing the values of either the variable capacitor or the inductor.could i just add an inductor in parallel for this? it doesn't have to be great, i just want to have a portable receiver, as i already have a good sw receiver. thanks in advance

[5B4AJB]

You can add SSB quite easily, all you need is a small oscillator (455kHz if I remember it right) which has a wire coming from the oscillator that wraps around the radio. The oscillator can be tuneable up & down about 5khz for fine tuning, but this is not essential.

I made one once using a 555 IC, long before I was licensed and it worked a treat!

It works by injecting a beat to the receivers intermediate frequency oscillator, causing a nasty hum (resolving SSB in the process)!

Here's a circuit diagram:- http://www.qsl.net/vu2ave/downloads/Bfo_455.pdf

[pasha]

so far i just have a standard 0.53-1.7mhz AM radio wouldn't i have to expand the range first? if i added an inductor in parallel to the inductor in the resonator circuit wouldn't that do the trick? thanks a lot this sounds really cool.

I should be able to get my license in the next week or so, so i am really excited. hope to be on the air soon.

[5B4AJB]

Like a lot of things in amateur radio, experimenting is half way to understanding, try adding several different, switched inductances and/or several different, switched capacitors.

There might not be very much on SSB within your standard tuning range, but plenty outside of it!

Try constructing a multi-turn MW loop antenna and inductively couple it to your radio (that is, just put it near your radio).

Your resonant frequency can be worked out with:-
1/(2*pi)*(sqrt L*C)
Where L is the inductance and C is the capacitance

I think that's right for the formula, just have a check on the web, you should find a calculator for it...