Tube Depot had these R-Core power trannies on sale (USD $39.95) last month, so I bought two for experimental fodder..
http://tubedepot.com/tr-pw-879s.htmlAs produced, these have a 100 VAC primary, and 260VAC @ 150 mA, and 6.3VAC @ 3A secondaries.
These can be run with 120VAC on the primary, and the secondaries will then be 312 VAC, and 7.56 VAC, under rted current loading.
For my test, I fed the primary with 100VAC from a Variac, with the 260VAC winding loaded with a 40W, 230V Philips ligght bulb (approx 180 mA load at 260V),
and a 6080 (2.5A load) on the 6.3VAC winding, and ran it for several hours,. The R-coe transformer just barely got warm, so I would presume
that it could handle even heavier current loading, by at least 20%.
I have an idea for a good application for these trannies, and that is an 8BQ5 / 8CG7 stereo SE amp. With 120VAC on the primary,
the lightly loaded filament winding would deliver fairly close to 8VAC, and the HV secondary, at 312 VAC could then be FWB rectified,
with a CLCRC filter string, which would deliver around 360VDC for the power stages, and 300-325VDC for the driver stage, which could be either a standard
grounded cathode, or with an extra tube, SRPP drivers. (I've used 6CG7 SRPPs, driving EL84s and 6GK6s with very good results).
Such a circuit would consume approx 80-85 mA B+ current, and either 1.65 or 2.1A filament current, which are well below the winding's 3A rating.
These power trannies were originally designed for this Japanese stereo 6L6GC SEP amp kit,
http://tubedepot.com/diy-ek-tu-879s.html so the lesser-powered 8BQ5 design would be a relatively lightand easy load for the PSU.
I don't know of an 8V filament version of a 12AX7A, otherwise this would work nicely with the Budgie SE circuit board (though not fit on the Budgie's top plate.
8CG7s would not have sufficient voltage gain for proper operation with the NFB loop, but are OK if no NFB were used.
The Russian 6N2P which is essentially a 6AX7, could be used with a 5 to 6 ohm, 2W dropping resistor in series with the filament.
/ed B