CTE Internaional (UK) sold the TR45 transverter (40 meters) in 1980s.The PC boards are silk screened Electronic Systemshttp://myweb.tiscali.co.uk/hotfusion/tr45.htm
Electronic Systems TR-50, 6-meter transverter (circa 1996), schematichttp://snoopy.tippete.net/~ik5pvx/ElectronicSystem_Transv50MHz_sch.pdf
Jesús M. Losada, EB1AGG (Spain) has one of these HF transverters, he may have a manual.
An ES TB3 just sold on eBay by a Canadien seller, islanderonbowen,
auction #300945595992 on August 13th.
ES (Electronic Systems) LB3, 3-band HF transverter (seller description).It covers frequencies around the 20, 40 and 80 meter amateur bands.
It was made in Europe and originally was intended, from what I can gather, to take input from a CB radio,
and put the operator in the "shortwave pirate" broadcast bands just below these amateur bands.
It takes a radio from 27.5Mhz to 28Mhz, it will cover each of these shortwave broadcast/amateur bands.
3-4 watts in gives you 20-30 watts out, depending on frequency and band.
Here's how it works (this is from what I pieced together, as there is very little documentation available anywhere).
You inject a signal into the transverter, it uses 3 crystals (one per band) to subtract from the injected frequency and give you the final frequency. The crystals are 13.400 for 20 meters, 20.692 for 40 and 24.000 for 80.
So if you set it to 20 meters, and you are operating your radio on a frequency of 27.600 Mhz, say, that will give you a final frequency of 14.200 (27.600 minus 13.400). It works in the same way for the other bands.
The resulting frequency is pretty accurate, but you also have a clarifier on the transverter for fine tuning.
And, of course, it will operate in whatever mode your radio operates in.