According to the ads from RME for the device, the HF-10-20 converter is of value for extending the usefulness of older boatanchor receivers with a limited top band. The converter is also an excellent accessory for a fixed-frequency receiver that can be fixed at 7 MHz.(For an example, see the Navy FRR-26 receiver. It is also useful for providing bandspread in the 10, 15, and 20 meter ham bands for receivers with no bandspread or with very limited tuning range for those bands. One example of such a set is the Hallicrafters SX-62. And, of course, it is fun to use one of these with a modern set such as the little Grundig.
Repairs After a thorough cleaning, application of deoxit on the controls and sockets, and the usual safety checks and slow power-up, I found this device was in good working order. No repairs were needed. I do not have a schematic, but the circuit is relatively simple. I tweaked the antenna and RF trimmers and adjusted the oscillator settings for each band for accuracy. A good frequency counter is handy for such adjustments.
Before experimenting with one of these, I did not know the various useful applications for such a converter. My thanks to John NC8V for giving this piece a good home.
The RS Science Fair "Globe Patrol", was the previous item on the bench.