[JMS] 90801

[Wilson Lamb]

Do we have any actual operators of the 807 exciter?
I have one now and am planning to drive it with my Variarm.
Does anyone know where to find a genuine Millen schematic?
I have one from the web, but it's not stamped, so I don't know if it's accurate.
It's been interesting to start looking at the exciter, which seems strangely designed, to me.
Why a 6L6 first stage?  It's not a great osc tube and is WAY too big for driving an 807!
Even going down to a 6V6 seems more reasonable.
And how strange the rig throws away bands by not being able to run the 6L6 straight through.
If one has a Variarm, 90700 version, one cannot operate 80m, because of the 6L6 problem.
Looking at the schematic, it seems I can jump3 and 5 on the 6L6 socket, with the B+ disconnected from the tank coil, and plug a B&W coil into the xtal socket.
I don't have the coupling unit for the Variarm, so I could feed it to the link on the B&W coil and be all set.
My Variarm puts out a solid 2W on 80m, which should be more than enough to drive the 807.
And is the 807 reliably stable?  They are notorious oscillators and the 90800 has no neutralization or even a parasitic suppressor in the plate!
I want to run the 807 with fixed cutoff bias, as recommended in the manual, but with osc keying, so it has to be stable key up.
And why in the world would anyone bury all those components in a skinny chassis, with very poor access?  Any serious work around the osc socket will require removal of components!  Using a removable top plate on the chassis would solve this problem.

Speaking of design, my unit has a variable coupling cap, but it's shown as fixed on my schematic.
The manual talks about changing it if more drive is needed, so I expect mine is a retrofit?

I don't have a lot of time for this stuff, but will plug along until it's working reliably, so I can use it in CX.

Any operational experience or voltage measurements would be appreciated.

BTW, the Variarm is quite stable and has a fine note, very usable.
I've talked to SC, IL, MA, NY, and PA, mostly with good reports and I have good reports, amazing really, from NH and VT on the Reverse Beacon Network, amazing!

Wilson
W4BOH