24-12-2013, 03:21 PM
The low ohms readings will depend on the minimum indication that the test meter can resolve, they can vary between types and makes.
On the face it looks like you have low ohms readings which would indicate that the coils are ok.
It is possible to tweek the RF alignment without a signal generator, if you look at the manual the RF alignment instructions are in there.
In all this we are assuming that the radio is in a good or reasonable reception area....
Before attempting any RF alignment you need to check that the Oscillator is running at the right frequency, you can check this without a signal generator, tune to a known station near the low end of the band and then one near the high end of the band, these should more or less coincide with the correct position on the tuning scale, most station frequency/wavelengths etc can be found on the internet. If the stations are to weak to identify then connect a few feet of wire to the external aerial socket (Skt 1) If all is ok then you can proceed.
There are two RF adjustments for MW, one will be for the RF tuning coil on the ferrite rod (L4/L5 assembly), to adjust that then first make a reference to where the coil is on the ferrite rod, you can do that with a pencil so that the coil can be returned to its original position if needs be then tune the radio to 600Khz (500 meters) with the radio switched to MW, if there is no station at 600Khz then adjust the coil assembly by sliding the coil former either way along the ferrite rod for maximum background noise, you might have to crank up the volume, be careful not to force the coil, be careful not to damage the coil windings, the coil former might be sealed on the end with some wax or other substance to the ferrite rod or it might have a thin piece of material running between the coil former and the ferrite rod, either way you will need to make the assembly slidable along the rod without excessive force.
Once that is done then you need to tune the radio to 1.5 Mhz (200 meters) then adjust TC4 for maximum background noise. TC4 is the MW RF Trimmer, that also might be sealed with either wax, a blob of paint or varnish, any seal should crack off when you adjust the trimmer. Before you adjust the trimmer make a note of the position of the screw or nut and also the direction and number of turns you adjust it by or parts thereof either clockwise or anti clockwise so that it can be returned to it's original position if needs be.
These two adjustments are interactive so you might have to do them both a couple of times in succession to obtain maximum background noise at both alignment points.
Lawrence.
On the face it looks like you have low ohms readings which would indicate that the coils are ok.
It is possible to tweek the RF alignment without a signal generator, if you look at the manual the RF alignment instructions are in there.
In all this we are assuming that the radio is in a good or reasonable reception area....
Before attempting any RF alignment you need to check that the Oscillator is running at the right frequency, you can check this without a signal generator, tune to a known station near the low end of the band and then one near the high end of the band, these should more or less coincide with the correct position on the tuning scale, most station frequency/wavelengths etc can be found on the internet. If the stations are to weak to identify then connect a few feet of wire to the external aerial socket (Skt 1) If all is ok then you can proceed.
There are two RF adjustments for MW, one will be for the RF tuning coil on the ferrite rod (L4/L5 assembly), to adjust that then first make a reference to where the coil is on the ferrite rod, you can do that with a pencil so that the coil can be returned to its original position if needs be then tune the radio to 600Khz (500 meters) with the radio switched to MW, if there is no station at 600Khz then adjust the coil assembly by sliding the coil former either way along the ferrite rod for maximum background noise, you might have to crank up the volume, be careful not to force the coil, be careful not to damage the coil windings, the coil former might be sealed on the end with some wax or other substance to the ferrite rod or it might have a thin piece of material running between the coil former and the ferrite rod, either way you will need to make the assembly slidable along the rod without excessive force.
Once that is done then you need to tune the radio to 1.5 Mhz (200 meters) then adjust TC4 for maximum background noise. TC4 is the MW RF Trimmer, that also might be sealed with either wax, a blob of paint or varnish, any seal should crack off when you adjust the trimmer. Before you adjust the trimmer make a note of the position of the screw or nut and also the direction and number of turns you adjust it by or parts thereof either clockwise or anti clockwise so that it can be returned to it's original position if needs be.
These two adjustments are interactive so you might have to do them both a couple of times in succession to obtain maximum background noise at both alignment points.
Lawrence.
