Hey Paul,
I'm doing the same thing here except I had
a new pair of EL-34's kicking around so I chose to
use them. I'm not as far along as you are, I just
brought the LV up yesterday and am getting nice
waveforms to the EL-34 grids.
You mention that your using the stock speech
amp. Is that to say you didn't change it per Tron's
article? I also wonder what Ranger you have? The
EARLY Ranger without Taps for the bias board on the
power xfmr, or the later model with the "Y" taps?
I am using the WA3DSP scheme here, which differs
from Tim's in that both half of the phase inverter are
powered from the LV supply and only uses 1/2 of the
12AX7. The owner of this unit wanted the fully adjustable
output power and the heat reducing items that are
implemented in this article.
http://www.crompton.com/hamradio/JohnsonRanger/RangerRestoration.html I made solid state plugins for the rectifier tubes
on this one and have been trying to keep the LV to
around 300V, but as it sits now with the tube fil. at
6.3 VAC the LV supply is just above 440 VDC. Normal
AC line voltage drives the fil. voltage to about 6.8
and the LV is close to 450 VDC. I already have the 5.0
volt winding wired to buck the AC line but need to add
an external job. "I luv my Variac!"
The VFO crapped out somewhere along the line here
so I need to get that going before I can do much more
with the Mods. This Ranger came here all "Cooked" out
from excessive Line Voltage. It's an "Early" model
without the "Y" taps. I wonder if Johnson added a few
turns to the secondary side of the later production Xfmrs
to keep up with the ever rising line voltage?
It's quite an interesting Mod. and I am enjoying
doing it. I'll try to get some pix of my waveforms later
today. I wonder if your distortion is from excessive
voltage. My 12AX7 has Ep 120 and the 12AT7 phase inverter
has Ep 240 triode 1 and Ep 250 triode 2 with my LV
adjusted to 300 VDC. Of course the fils are only at 5
volts. Waiting for MOSFETs for regulator.
GL
Please keep us posted as the situation develops!
Thanks
/Dan