It was a toy in the beginning, the more I use it, the better I like it! Actually, I like it that much that I ordered a second one.
There are plans for this second one. Since there is a lot of space inside its' housing, there is room for modification and experimentation. Many years ago, I heard about a kit that converts a FRG-7700 into a transceiver. Cool, I thought, and forgot about it again. And now, the idea is back, with something that connects in either of the two, the FRG-7700 or the HF3. Both are double conversion superhets, both use a lower intermediate frequency of 455kHz. Using the generated frequencies, one could imagine to convert a single side-band signal all the way back from 455kHz to whatever the receive frequency would be.
I figure, it would be the question of just some NE612 mixers and two crystal filters, one for 455kHz (side-band) and one for the first intermediate frequency.
One further could consider to add some temperature control to the reference oscillator.
And, who knows, maybe this could be an easy way of producing some QRSS-signals too.