The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

Hi all!

After some modifications and a proper re-alignment in order to let the radio perform perfectly for it's class, I would like to add one item to complete the radio's modification and that's an external S-meter.

Now, I might have a slight idea where to look on the PCB to find a point where I can hook up an external S-meter but I want to be sure and confident in identifying the particular points which are suitable as a source for an external S meter.

Any suggestions are greatly appreciated!

Cheers,

John

There is an integrated circuit (IC-1), you would hook up the S-Meter in this circuit off the cathode of D-14. Everything you need should already be there.

You will probably need a buffer amp as you may load the signal from the IC.
Just couple a 10 to 47pF cap an NPN transistor and make up a buffer amp.
This is the best way as you will get a better meter reading.

James.

Thanks for the helpful reply's!

I wasn't sure that the cathode side of the diode D14 was the right point for hooking up an S meter but I tried it a few hours ago and it seems to work perfectly!... However, it needs some alignment obviously due to the fact that the used s meter was a little too jumpy as signals with a santiago 8 a 9 reading on the display of the 2950DX hit 30db+ on the external s meter

Anyway, the trick at this point is to carefully attach a wire to the bandside of D14 and lead it to a jack chassis mounted somewhere at the back and we're good to go I suppose!

I'll keep you informed!

Cheers and thanks,

John

How did u get on with the meter mate someone round my way was wondering if it could be done

Hi!

First of all my apologies for the late reply! I just bumped into this old thread while searching the web for any more mods for my 2950DX!

Anyway, Initially I decided to let the idea of an external S meter go because I wasn't able to obtain satisfactory readings from this particular meter despite the fact that it's a good meter. I found out that the s meter had to share it's signal with the original s meter of the radio so the readings were not reiable. I think I have to interrupt the original feed to the internal s meter in order to get the full signal redirected to the external s meter for better readings.

Unfortunately this eliminates readings on the internal s meter decisively... However, I if manage to get a chassis for the external which switches between internal when the jack isn't plugged and external when plugged it should be fine.

I'll keep you informed!

Cheers,

Breaklight