Looking for information on Dow-Key DKC-TR tube type TR switch. I have
one without documentation. I found the box it came in, no
instructions.
regards, cullen K5HAL

On Tue, 19 Jan 2010, cullen wrote:

Looking for information on Dow-Key DKC-TR tube type TR switch. I have
one without documentation. I found the box it came in, no
instructions.
regards, cullen K5HAL

What do you want to know? Any old Handbook is likely to have a circuit
that can't be too different from a commercial product (they all have to
be about the same) and describe how to hook them up.

If you're looking for historical information about the specific device,
then I don't know. What's so puzzling about the unit that you need to
know?

Michael VE2BVW

cullen wrote in news:26b23c2c-b593-43b7-98ca-
:

Looking for information on Dow-Key DKC-TR tube type TR switch. I have
one without documentation. I found the box it came in, no
instructions.
regards, cullen K5HAL

This maybe of some help:

http://www.n4mw.com/dkc-trm.pdf

--
Panzer

cullen K5HAL wrote:
Looking for information on Dow-Key DKC-TR tube type TR switch. I have
one without documentation. I found the box it came in, no
instructions.


Hi

I also have a DKC-TR, with no instructions.
It should be usable on 160 thru 10 meters.

The two SO-239 connectors that have continuity thru the center pins
are for antenna and TX connections (doesn't matter which is which).
The other SO-239 (at narrow end) goes to the RX.

The cable has a black lead to 6.3V, a red lead to approx 125 to 150 VDC,
and a shield to ground.

The tube used is a 6AH6 pentode.

You should include a low pass TVI filter between the TR switch
and your antenna.

The BAMA mirror site has instructions for the DowKey model TRM
TR switch, which includes general TR switch usage guidance,
but is a different design, using a dual triode tube type 12AZ7.
Keep the cable length between the TX and the TR switch as short
as possible, to avoid "suck out" effects on RX sensitivity.

Also, the TR switch should be used with a class C final, or one
which has cutoff bias applied to the finals during key-up, to avoid
increased white noise in the rcvr.

73,
Ed Knobloch

On Jan 19, 4:04�pm, Edward Knobloch wrote:
cullen K5HAL wrote:
Looking for information on Dow-Key DKC-TR tube type TR switch. I have
one without documentation. I found the box it came in, no
instructions.

Thanks everyone. I had found most of the references. The one piece of
information I did not have in hand was the wire color code. I used
this for years with an HQ-150, CE-20A plus the LA-1. The sheet on the
DKC-TRM did not satisfy my curiosity and my old handbooks are now in
storage.
Now that I have your attention, why is the tube type TR switch no
longer made or used? The idea seems great.
Regards, cullen

On Mon, 25 Jan 2010, cullen wrote:

On Jan 19, 4:04�pm, Edward Knobloch wrote:
cullen K5HAL wrote:
Looking for information on Dow-Key DKC-TR tube type TR switch. I have
one without documentation. I found the box it came in, no
instructions.

Thanks everyone. I had found most of the references. The one piece of
information I did not have in hand was the wire color code. I used
this for years with an HQ-150, CE-20A plus the LA-1. The sheet on the
DKC-TRM did not satisfy my curiosity and my old handbooks are now in
storage.
Now that I have your attention, why is the tube type TR switch no
longer made or used? The idea seems great.
Regards, cullen

Very few people use separate receivers and transmitters.

Few are interested in the sort of break-in that you could get
from a TR switch, they can live with relay changeover.

Transceivers sometimes use the same thing, but it's done with
semiconductors not tubes.

Michael VE2BVW

Michael Black wrote:
Very few people use separate receivers and transmitters.

Few are interested in the sort of break-in that you could get
from a TR switch, they can live with relay changeover.

Transceivers sometimes use the same thing, but it's done with=20
semiconductors not tubes.

And you can make a pretty good one for not much money using PIN diodes.
The Handbook even used to have a design.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Some transmitters produce a strong signal into the antenna
in spot mode when an electronic TR switch is used.
I measured about 275mW out from my Ranger II on 40m in "tune" mode,
and 125mW out in "standby" "VFO Zero" position.

You might consider switching in a dummy load before VFO-swishing
the band.

73,
Ed Knobloch

On Tue, 26 Jan 2010, Edmund H. Ramm wrote:

In cullen writes:

[...]
why is the tube type TR switch no longer made or used?

How did you arrive at the latter conclusion? I for one use an
E.F. Johnson T/R switch.

Have you been to your local ham store and looked over their selection
of T/R switches lately?

Michael VE2BVW

Michael Black wrote:
On Tue, 26 Jan 2010, Edmund H. Ramm wrote:

In cullen writes:

[...]
why is the tube type TR switch no longer made or used?

How did you arrive at the latter conclusion? I for one use an
E.F. Johnson T/R switch.

Have you been to your local ham store and looked over their selection
of T/R switches lately?

My local ham store doesn't have a good selection of anything other than
sealed appliance transceivers.

There are tube type TR switches made for military applications, but for
the most part they are too slow for modern signalling methods which is
why the PIN diode units are such a big deal.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."