Does anyone have the schematic for the vintage tube-based KROHN-HITE
MODEL 440-A Oscillator that they could scan and send me, or point to a
link (I haven't found one.) It's bigger than some boatanchors!
Mind has just died - no oscillation (but it was working.) I have
found a dead 6H6 tube (double-diode, heater open circuit - it may not
be critical and I could replace it with a 6AL5 with a base adapter);
also found a low emission 6AU5 (beam power tube) - it seems to be a B+
regulator but I still seem to have good B+. All 6SL7's test OK to
"good"; I subbed the worst one but still no oscillation. All other
tubes test OK to "good+". Now I'm stuck! I'm blind w/o a schematic on
this one.
Thanks for all replies.
Cheers,
Roger
PS. email address shown is fake (anti-spam.) Kindly use analogdino at
(ta-boy) rogers dot(ty as they) com(e), suitably decoded. Tks.
PPS. Also posted on RAR+P and sci.electronic.repair as group readers
differ but do overlap. I hope no-one is offended.

Engineer wrote:
Does anyone have the schematic for the vintage tube-based KROHN-HITE
MODEL 440-A Oscillator that they could scan and send me, or point to a
link (I haven't found one.) It's bigger than some boatanchors!
Mind has just died - no oscillation (but it was working.) I have
found a dead 6H6 tube (double-diode, heater open circuit - it may not
be critical and I could replace it with a 6AL5 with a base adapter);
also found a low emission 6AU5 (beam power tube) - it seems to be a B+
regulator but I still seem to have good B+. All 6SL7's test OK to
"good"; I subbed the worst one but still no oscillation. All other
tubes test OK to "good+". Now I'm stuck! I'm blind w/o a schematic on
this one.
Thanks for all replies.
Cheers,
Roger
PS. email address shown is fake (anti-spam.) Kindly use analogdino
at (ta-boy) rogers dot(ty as they) com(e), suitably decoded. Tks.
PPS. Also posted on RAR+P and sci.electronic.repair as group readers
differ but do overlap. I hope no-one is offended.


I found the cheapest KH 440-A service manual at
https://www.ridgeequipment.com/store...hp?query=440-A

--
David
dgminala at mediacombb dot net

On Jan 30, 9:31*pm, "Dave M" wrote:
Engineer wrote:
Does anyone have the schematic for the vintage tube-based KROHN-HITE
MODEL 440-A Oscillator that they could scan and send me, or point to a
link (I haven't found one.) *It's bigger than some boatanchors!
Mind has just died - no oscillation (but it was working.) *I have
found a dead 6H6 tube (double-diode, heater open circuit - it may not
be critical and I could replace it with a 6AL5 with a base adapter);
also found a low emission 6AU5 (beam power tube) - it seems to be a B+
regulator but I still seem to have good B+. *All 6SL7's test OK to
"good"; I subbed the worst one but still no oscillation. All other
tubes test OK to "good+". *Now I'm stuck! I'm blind w/o a schematic on
this one.
Thanks for all replies.
Cheers,
Roger
PS. *email address shown is fake (anti-spam.) *Kindly use analogdino
at (ta-boy) rogers dot(ty as they) com(e), suitably decoded. *Tks.
PPS. Also posted on RAR+P and sci.electronic.repair as group readers
differ but do overlap. I hope no-one is offended.

I found the cheapest KH 440-A service manual athttps://www.ridgeequipment..com/store/manuals/search.php?query=440-A

--
David
dgminala at mediacombb dot net

Thanks, Dave, I may get it. At $15 plus mailing it's the same price
as I paid to for the 440-A!
Cheers,
Roger

On Jan 31, 1:43*pm, Engineer wrote:

(snip)

Thanks, Dave, I may get it. *At $15 plus mailing it's the same price
as I paid to for the 440-A!
Cheers,
Roger

Oops, perhaps not!
Subtotal $14.99
Shipping $23.75 (per this site)
Tax $0.00 (but see below...)
Total $38.74
Then there's 13% local Canadian sales taxes plus an iniquitous $5 fee
to collect them
Total $48.78
Plus about 5% x/c
Total over $51.00

I'll keep looking!
Cheers,
Roger