HOW TO CONVERT AM BROADCAST RADIOS TO RECEIVE ONE SIXTY METERS.


If you don't have a coms or general coverage receiver you can convert an ordinary am wireless. As most broadcast sets cover up to about 1630khz it is possible in most cases to tweak them upto above 1.8mhz.

With a signal generator and other service equipment the job is easy but I will explain how to do it with minimal gear.You will need two radios, one to be verted and the other to use as a signal source. Try to pick a nice sensitive one for the conversion to one sixty, as am radios can be picked up for a few dollars at junk sales these days it should not be to hard to find a suitable one in fact its often possible to obtain at very reasonable cost a general coverage set that covers the band, but most miss out on the lower Short wave portion of the spectrum. I have not had much luck converting a set from 2.3mhz down to 1.8mhz.

Back to the instructions, first tune the signal source set to about 1400khz this will, assuming a 455khzIF stage as in 99% of sets put the local oscillator on about 1855khz which can be used as a local signal in the set to be converted identify the local oscillator coil and slug, its usually painted red and when turned
it changes the stations, what you want to do is adjust this so all the am stations move down the dial. Put the two radios near each other and tune the to be converted set to the top of its dial ie the hf end, adjust the coil until you come across the carrier from the local osc of the set being used as a signal source. In most cases this can be achieved without to much trouble. The next step is to tune up all the rf and ant stages so they peak on one sixty this can be done by listening to the band noise and and adjusting for maximum sensitivity, for a wide band noise source go near a light dimmer or flouro light and tune for the loudest buzz.
Some times one can not obtain much sensitivity this is usually due to the fact that even with all the trimmers fully out the stages will not resonate high enough in frequency, this is bit of a problem but often one can just disconnect the trimmers and it will peak ok on one sixty, the problem with this is that the tuning won’t track so it will be very deaf on the normal broadcast band but since most people have plenty of radios to listen to it doesn’t matter, you can fiddle with r/c values and the rest but it all takes time so if a set is hard to convert just try another one.

Car radios are very good but hard to change, the simplest method is to remove all the ferrite cores from the inductive tuning arrangement, this will make it resonate close to 1.8mhz and use the local osc coil
slug to tune in the stations.

SSB RECEPTION (yuck)

Although we use AM because of the volume and clarity and easy reception with bash radios, a lot of the stations heard will be on ssb, to hear this just use the local oscillator of another radio as a bfo, this system works quite well on these frequencies, depending on the strength of the signals heard change the
distance between the two sets for the best result.

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