I purchased a Supreme brand "frequency modulator" ,Model 529, some time ago but have been unable to find any detail info despite looking through USA sites for test equipment.
What I believe I am looking at is a device which converts a CW signal to a FM signal.
The input sides are "CW & Gnd", the output side is "F.M. & Gnd" and lower down the front panel are two inputs (?) for "timebase".
The front panel connections match some of the info for other Supreme equipment but this item is not discussed beyond availability.
Inside are a couple of valves and a sealed block which seems to contain frequency reliant components.
Very nice cabinet and overall finish which is the reason I purchased this unit several years ago.
I am hoping someone else has some more ideas.

Descriptions here:

http://www.supremeinstruments.org/catalog1937-39page2.htm

and on page 48 of this document:

https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi9m7aAtdHzAhWS63MBHUjYDFMQF...

Add http://supremeinstruments.org/ Then analysers

I actually sync an oscillosope to the Signal Generator for alignment. At times it shows you nasty problems.

Thanks to GTC, the ad version is very similar to one I read some time ago but the 529 in my possession has a toggle switch at top centre and a lamp at bottom centre instead of the wo dials. I'm thinking there may be differences in age, but great starting point.

Thanks to Marcc, your link helped somewhat. It shows the 529 with the same front panel as mine and mentions that there is a later version with different layout which, also, is shown.
I guess I will need to make some time to generate a circuit for this.

I am a moderator on the US forum I can lodge an enquiry in their test quipment section. However, reverse engineering is common here.

Make absolutely sure that you take good quality photo's of the internals and the tripod is not obsolete. I start with a layout diagram by drawing, or retrieving valves pots & switches etc. and placing them in their relative positions, using the ancient AutoCAD.

The next step is to play "join the dots" & add the components & wiring. Once you have the layout its easier to translate that into a circuit.

As there is no obvious circuit on that website I have placed a request on the American site to see what transpires.

The ancient AutoCAD was bought with its optional Electrical symbols.

Marcc,
I don't use Autocad because in the professional work I have done I have found it to be backwardly unusable. What I use is "Turbocad" which reads and saves any Autocad file into any format, including Autocad - whatever version, for my access.
Thanks for your background work, I will advise when I have some detail and will require for yourself and GTC to complete a download to this forum when my work is complete. Not this week.

I am finally getting far enough out of covid lockdown to make my first visit to my latest Grandchild.

I have another request which I will post later with reference to an Australian made signal Generator from ITC. I have some background on this product, but will need time to collate a responsible data stream.

I do have a ligit. copy of TurboCAD but not currently on a computer. It does not have the battery of symbols that the older one has. The old oneis called Autosketch and is from around 1995. Its running on a computer built in 2000.