Pro-2042 alignment

[Edelweiss]

Hi!

My 2042 has gone a bit deaf on UHF, I cannot find any service manual for it. Maybe it's age related. Has anybody got some alignment instructions? Have access to radio test kit.

Much appreciated!

Mike

 

[Ubbe]

If you check different frequency bands and it's only UHF, 450MHz band, but both lower and the higher 800MHz bands are ok then it can only be the bandfilter for UHF that's gone bad. All amplifier components are the same and for each band there are switching diodes, that can go bad, that connects the different filters that are passive filters with capacitors and inductors. The components that can be bad are probably covered in epoxy and makes it impossible to repair.

There's no service manual that I know of but there's schematics on the internet and Optocom and Pro-2035 have an identical RF design.

Check that it's on the correct frequency. Over modulate with a 1000Hz signal until it barely starts to sound distorted and tune the signal generator +/- around the frequency to find the center where it has the least distorsion. If it's more than 3KHz off then set the correct RF frequency and tune the master oscillator. Do this with a 800MHz signal as the error will be worse the higher up in frequency you go.

/Ubbe

 

[Edelweiss]

Thanks @Ubbe, it is doing well on VHF and I do not know or have the circuit, UHF airband it's bad. On the BCT15X there is a a row of switched filters and LOs for each band if I remember and it may be that one of them is off if it is the same as well on this one. But ont he BCT there is not much scope to tune anything for each band. Have not opened it before. I saw that in the 15X that they cleverly put epoxy (looks like Araldite) over the filter SMD components which is nice but makes it a throw away item when you need to get to one. I saw a note from someone to adjust just one coil or so probably one of the master LOs or so but as I said it basically works, it is just one band that has the issue I believe. I also do not know what the transition frequencies between the bands are to do some more meaningful testing. OK, will have a look at this alignment for the master LO but don't have much hope. Maybe a diode switch is no good...

Cheers

M

 

[Ubbe]

When I looked at the Pro-2035 schematics it turned out to actually be the service manual. So now you can study the component layout and see if some of the switching diodes for the 280MHz-520MHz filter are not covered in epoxy and free to be measured.

realistic_pro2035 service manual.pdf

drive.google.com

/Ubbe

 

[iMONITOR]

Hi!

My 2042 has gone a bit deaf on UHF, I cannot find any service manual for it. Maybe it's age related. Has anybody got some alignment instructions? Have access to radio test kit.

Much appreciated!

Mike

You might have to worry more about failing capacitors than alignment.

 

[Ensnared]

I have this radio. Here is what I found:

Realistic Realistic-Pro-2042-Users-Manual- Realistic-pro-2042-users-manual

I am looking for the service manual.

 

[Ensnared]

Here is what I found:

Service Manual REALISTIC PRO-2042 SCANNER

 

[Edelweiss]

Thanks for the digging! A bit on the pricy side! Would you know if there are actually some alignment instructions in there as the preview just lists components. Often these manuals are very sparse...
Cheers Mike

 

[Edelweiss]

When I looked at the Pro-2035 schematics it turned out to actually be the service manual. So now you can study the component layout and see if some of the switching diodes for the 280MHz-520MHz filter are not covered in epoxy and free to be measured.

realistic_pro2035 service manual.pdf

drive.google.com

/Ubbe

Thanks @Ubbe ! How similar are these units? Will need to take the unit out of the rack and first do some quantitative measurements with some sig gens...

 

[Ubbe]

How similar are these units?

Almost identical. It was mostly firmware differences. PRO-2042

/Ubbe