[Elecraft] Mostly OT: TS-820

[Geoffrey Mackenzie-Kennedy]

Hello Tom,

Having spent countless hours in the company of members of the 6146 family,
from their conception, please be assured that even with zero RF signal drive
a 6146B will be undamaged provided that 1) Supply voltages are within
specified limits 2) "Real" DC bias is used for the control grid (Grid 1) 3)
Dissipation limits are not exceeded - in major part controlled by Grid 1
bias and 4) The circuit is stable and also free of parasitics. Grid 1 should
be RF loaded, as it will be in the transmitter. In other words the same
rules that apply to most tubes.

I do not know the Final's circuitry of the TS-820S, but I would guess that
it is two 6146s in parallel biased somewhere between AB1 and AB2. So the
caution about parasitics is relevant, but if that was a problem, it should
have shown up before when adjusting the output tank. I also assume that
there is a real" DC bias supply.

So have some fun! Good hunting!

73,
Geoff.
GM4ESD

----- Original Message -----
From: "Tom Skinner" <fzxtchr at verizon.net>
To: <elecraft at mailman.qth.net>
Sent: Saturday, February 26, 2005 1:53 PM
Subject: [Elecraft] Mostly OT: TS-820


> Hello group,
>
> I'm not sure where else to ask this question. I can't seem to get anything
> but an answering machine at the Kenwood Amateur Radio Tech support Center.
>
> While waiting for a new K2, I would like to get on the air (after a
> considerable absence) with an old (but very good) TS-820S. The problem
is -
> too much interference with the computer and TV at rated output. Since the
> neighbors are pretty close, I probably would interfere there as well.  I
> have done short tests at qrp levels with no interference.
>
> However:  Is it advisable to reduce the drive to qrp levels (for longer
than
> short tests) without damage to the 6146 finals?
>
> Thanks,
>
> Tom, K0PXL
>