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."

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."

On Wed, 27 Jan 2010, Edmund H. Ramm wrote:

In e.net Michael Black writes:

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?

Have you overlooked "latter", which refers to "used"?

The fact that you aren't likely to find a T/R switch at your local
ham store (if you happened to still have such a local store) is
an indicator that they aren't used, because if there was demand
surely there'd be a commercial product. One would also see the lack of
separate receivers and transmitters, as I already mentioned, so one
could gather there is less reason for such a device nowadays, and even
fewer are using non-matched separates, so that S-line or the SB-line
or whatever handles the switchover.

The fact that some still use them doesn't negate his statement. Surely
it's only a relative handful, and they aren't visible enough. Enough
time has passed since they were common that many hams likely don't even
know what they are.

In the old days there were multiple reasons for using them, and they
were often simpler than the alternatives. Nowadays, other things take
care of the task, whether it's a current equivalent of the TR switch
hidden away inside that transceiver or something else, so the only
people using them are those who want to run an old type station, or
have some specific use for it.

If he'd asked somewhere else, chances are good nobody would question
his point about "nobody using them" since there is less likely to be
users except by boatanchor types, and chances are good that if posted
elsewhere someone would say "what's that?".

Michael VE2BVW