Sylvania 5933 807W FU7 Vacuum Tube 13GB5 Plate Cap This trio of US-made 6X4

This trio of US-made 6X4 tubes was tested on our Paul Hart-calibrated TV7/U for shorts

" "My Darling's Ring

4-17 188-5 and 2-48 188-5 date/provenance codes

I am playing them now in my Radio Craftsman RC-2 mono blocks with Pink Floyd's "Obscured By Clouds" and they sound terrific

On the Maxi-Matcher

Sylvania 5933 807W FU7 Vacuum Tube 13GB5 Plate Cap This trio of US-made 6X4This Sylvania 5933 807W FU7 output tube was tested on our Maxi Matcher 2 for shorts, gas and transconductance with 400 volts on the plates and a bias of 48 volts. There were no shorts or gas. Plate current draw was 17. 2 milliamps while transconductance measured 2050 micromhos. (New 5933s typically test from the mid teens to mid 30s with transconductance from 2200 micromhos). I am playing it now in my Musical Paradise 301 MK 3 (with an adapter, not