S meter

I saw a picture on Face of a Hallicrafters S-108 receiver with an outboard S-meter from Lafayette.  It was a TM-59a from the early 1960s, here is the catalog page from 1962:

And the inflated price:

Here is the schematic clipped from the BAMA manual:

A very high impedance triode DC amplifier.  It wouldn't be that easy to add to a transformerless set like the Hallicrafters S-120 though - powering the filament / lamps would mess things up for one thing.

schematic source is the TM-59 manual:

 https://bama.edebris.com/manuals/lafayett/tm-59a/

IF I ever do bring back my Hallicrafters S-120 as a receiver, an S-meter would be a nice thing to add.  

BTW, I'm still not sure what radio (with S-meter) was used on Mission Impossible:

https://wb9kzy.blogspot.com/2022/08/s-120-with-meter.html

but it was certainly in the same S-120 family.  The Lafayette HE-40 was similar to the S-120 but added the meter and a couple of switches:

the inside looks just like an S-120

The HE-40 schematic shows the S-meter connections:

The S-meter is a fairly simple meter/resistor connected to the AGC circuit.

I have seen these contemporary versions of the TM-59 on Ebay:

https://www.ebay.com/itm/365307385755

They are for the two Yaesu rigs (FT-857 and FT-897) but I wonder if the S-meter could be adapted to another radio.  The connection from the meter to the radio is via a stereo 3.5 mm plug.

LDG also used to sell something similar:

https://www.dxengineering.com/parts/ldg-ft-meter

manual: https://hamradio.vazenterprises.com/wp-content/uploads/FT-Meter-Manual.pdf

My FT-450D doesn't have the 3.5mm jack for such a meter, just the FT-857 and FT-897 rigs which are smaller units.  Anyway I wouldn't be buying due to the tariff tax.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm