[Milsurplus] WWII Japanese 94-5 Rcvr Raises Again.

[David Stinson]

Thanks to kind help from Bill Howard, Philip McCoy and others,
the WWII Japanese 94-5 receiver is currently listening to
80-mtr CW.  I brought the B+ up slowly and saw no problem
high currents or overheating components.  Clean/Lube and
a battery pack and the set is playing, sans audio PA stage.
Like all simple regen sets, the tuning and settings are
touchy, but workable.  There is some pulling of the
oscillating detector when I bring my hand near the antenna,
indicating less isolation by the RF stage than expected.

As Bill Howard said, the audio output transformer primary
is open- doubtless the result of a ham trying to use
a 90-volt supply with B-minus grounded ( no, no, NO!),
resulting in no grid bias and a burned-open primary.
It quickly joined "the choir invisible" along with
countless BC-474 and BC-348 audio output transformers,
murdered in the same fashion.

I was determined this unit was not going to be modified,
nor have parts removed.  I therefore used a trick from
my work with ARC-5 receivers.  I tapped off the audio PA
grid with a .1 uFd cap and ran a lead out the headphone jack
to an external amplified speaker.
I could also have jumpered headphones across the open
primary, but I don't like having B+ voltages running
over my head and hears, especially if the weather gets hot.

I've heard people say these WWII Japanese radios were not
built well.  From a mechanical standpoint, I must
disagree concerning this radio.  It's hand-crafting is
at least as good as any early war Allied ground set
I've seen, and better than some.
It looks quite well made to me.

A few notes-
The radio is extremely microphonic- the worst I've ever seen.
I have to locate the external speaker a few feet away
to stop the feedback.
Seems to center on the triode detector, which is mounted
on a shock base- an attempt to address this problem, I suspect.
Padding the tube with tissue didn't help much.
I hope this is an itchy detector tube and not "standard issue?"

Band #1 does not work, but the rest function well.
Is an open in the band #1 section of one of the coils common?

Are these original tubes 1.2 volt, or 1.5 volt?

Anyone have a 94-5 transmitter they'd like to trade?
Once the microphonic problem is fixed, this would
make a dandy little field rig.  I'd dearly love to
display it next to my SCR-288;
they were contemporaries in the Pacific Theater.

More as I learn more, and thanks again to everyone for
the help.

73 DE Dave AB5S