By a "handwound" transformer, I presume you mean units from handwoundtransformer.com, perhaps? Though their transformers are of very good design and fine quality, their service is poor and extremely slow. I currently have a large quantity of iron on order from them that's now several months overdue. A friend of mine got his 300B transformers after nearly 3 months, while another's pair of 3.5K 5 watt SE OPTs took almost a year.

They've lied about half a dozen times and said they would ship within a few days, the last of which was about 2 weeks back. I'm fed up and requesting a refund next week if I don't receive the iron by then. If you don't mind waiting an average of 6 months for a set of x-formers to do an amp, I'd recommend them. If not, don't waste your time.

Hammond power iron would be good in your transmitter tube amp. As far as OPTs, there aren't many off the shelf units rated for that kind of voltage and offset DC current. I think Hammond makes one or two that can handle it, not sure. Perhaps Eric Barbour will see this and chime in, if he knows source of proper OPTs that you won't have to sell a kidney to buy!

Though offensively expensive, Plitron makes a couple models of transmitter tube OPTs. I've bought several OPTs from them before, both SE and PP, and they are unbelievable. The bass is very tight and extended, the midrange refined, fluid, and sweet, and the highs extended, completely transparent, detailed, and chimey. They seem to pass all the nuances and harmonic content that makes the music sound like REAL music. Though the highs are very similar, my Tamura F-475s sound veiled and grainy in the mids compared to my Plitrons, and the Plitrons' bass response and quality simply plows the Tamuras under. Plitron's service is also good; they WILL arrive on your doorstep within 4 weeks after you call in your order, bar none, and not a day later. I know I may sound like a Plitron salesman, but I'm not. They're just great iron.

Thermionic