Doug wrote:
> Here is the link, it is a product from LDG.
>
> http://www.ldgelectronics.com/products.php?cID=7&pID=2&v=1
>
> 73, Doug
> N9XTF
>
>
I have a bit of heartburn with this scheme. The LDG tuner is an L
network. The
Q of an L network is not independently selectable. It depends on the
ratio of
impedances to be matched. For example, to match the 135 Ohm impedance of
the pair of 813s under discussion, the L net would have a Q of only 1.3.
This is
far less than the 2 usually used in older amps or the 3 to 5 recommended
for solid
state drivers. It gets worse as the input impedance of the tubes
decreases. For
instance, a pair of 3-500Zs with an input of 60 Ohms, would result in a
Q of only
.45!
Another problem I see is that with a GG amp, the input and output are
in series.
With my old Drake L-7, if the output is mistuned, the input SWR is high.
This
causes my FT-1000 to throttle back the drive power automatically. As the
output
of the amp is tuned, the input SRW decreases and the drive power comes
up. This
make for an easy tuneup procedure. With an autotuner on the input, it's
going to be
constantly chattering looking for a match as the amp is tuned. Perhaps
it can be
programmed to come up in the preset mode rather than the auto mode.
Good idea....needs work.
73, Roger
--
Remember the USS Liberty (AGTR-5)
http://ussliberty.org/
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|