> To: Bob Perring
> I still need the schematic.
OK, I'll try and get one in the mail to you. Keep my email address around
and remind me in two weeks if I get side tracked.
> BTW, if you have one of these guys, how has/does it play?
Fine, when they work. I have 2 actually....
(For those not familiar, the Dentron GLA-1000x series is a four tube
desktop amplifier using 6LQ6/6JE6 "horizontal output" type beam tubes.
Although they have been around for many years, the low cost and avail of
the these tubes made them popular. The first version of this amplifier
lacked tuned input, they all lacked proper (common sense) cutoff bias in
the receive mode, were very non-linear when overdriven, exceeded the
recomended max plate voltage of the tube and in general... went up in
smoke quite a bit.
They are now found at flea markets in various conditions, cheap.
I enjoy using the parts as building blocks in new projects.
> I picked mine up for $200.00 in mint shape and have it in a hard
> case brief case...... Ready to travel.
When transporting the unit, I would pop the cover off and provide
additional packing around the tubes for support.
For a "working" unit that's at good deal. The sweep tubes are getting
kind of expensive now to replace. There are some serious design problems
I would address with the amp. First, a simple mod to cut off the tubes
when in the receive mode. It uses the "extra pair" of relay contacts on
the main TR relay. You can add tuned input to a GLA 1000 and 10 meters to
a 1000C if it's not onboard already.
There is a crazy PC board anchor point for the tube anode leads at the
top of the HV choke. I would remove it as it's one heck of a big
reactance.
I wrote the entire mod(s) up as an articly for QST years back, but the
amp quickly fell from favour (as did a lot of Dentrons) and the article
was never turned in.
There are people who will state that Beam/Sweep tubes are not very
linear. This is true for the most part, especially when "overdriven".
Just for the record, General Electric designed a "sweep tube" just for RF
service. The 8950 is this tube, no longer mfgrd that I know of and hard
to find. The 6LQ6/6JE6 and similar family of tubes are avail, but the
prices are way out of line to purchase new.
> Just hope it works as I expect.
> Right now, I can read 650 watts output on my Bird meter,
> so I am happy.
Use with low duty cycle modes only...
I would only use it with SSB, look up the amplifier tuning aid on Rich's
web page. Or at seriously reduced input power levels for CW/AM
> I can sure use the schematic.
You'll need it sooner or later.
Cheers
Skip wv6f
mays@indigo.ucdavis.edu
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