Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV

Gary Pewitt wrote:
Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV

Ground the antenna, ground the rig chassis, float the rig RF In.

Gary,
The biggest problem would be in trying to use the radio without
connecting an antenna to it. If you can be sure of always doing that,
then I would ground the unused antenna (personal preference, radio is
grounded anyway). Same thing if you ground the radio's antenna
connection. If you forget, it causes problems, sometimes big ones. I
tend to make allowances for my bad memory. You may not have that
problem, so...
- 'Doc

On Sat, 11 Oct 2008 22:12:20 -0500, Gary Pewitt
wrote:

I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up.

Hi Gary,

I see your problem right here.

There are four ways to hook these up.

73's
Richard Clark, KB7QHC

Richard Clark wrote:


Hi Gary,

I see your problem right here.

There are four ways to hook these up.

73's
Richard Clark, KB7QHC

Hmmm, I guess you post implies you are a bit short on beginning with the
first way?

How typical ... yawn

Regards,
JS

On Sun, 12 Oct 2008 18:16:25 -0700, John Smith
wrote:

Richard Clark wrote:
There are four ways to hook these up.

How typical ... yawn

Go back to sleep, Brett. You certainly added nothing.

Switch one center posts: Rig - now called the rig switch
Switch two center posts: Antenna - now called the antenna switch

Rig switch position 1: both sides to ground
Rig switch position 2: both sides to antenna switch position 1
Antenna switch position 1: both sides to rig switch position2
Antenna switch position 2: both sides to ground

Rig can be
1. open
2. grounded
3. to switched antenna

Antenna can be
1. open
2. grounded
3. to switched rig

Both rig and antenna can be independantly open or grounded, or
interconnected. No real advantage in the open positions, but they are
available as a 6 state solution. As such, a 4 state solution that was
sought.

More switches, more states. Classic cross-point switching.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

...
Go back to sleep, Brett. You certainly added nothing.
...
73's
Richard Clark, KB7QHC

I'll wakeup, when something interesting comes about ...

Regards,
JS

Richard Clark wrote:
Rig can be
1. open
2. grounded
3. to switched antenna

Antenna can be
1. open
2. grounded
3. to switched rig

As a refinement I'd put a dummy load on switch #1 so that the choices would be:
Rig can be:
1. Open
2. To dummy load
3. To switched antenna

The antenna switch would remain the same -- open, grounded or to switched rig.

I'd rather run my rig into a somewhat reasonable load rather than a short to
ground during the inevitable instance of forgetting to set the switch properly.

If running less than say 200 watts output then one could even use an
incandescent light bulb for the dummy load. It would presumably light up if
one were to inadvertently transmit in that configuration. So, the rig would
be at least partially protected and the operator would have some indication of
why no one is answering his CQ. Maybe a *red* light bulb?

One could also physically (not electrically) parallel the switches so there
were only two configurations. The rig connected to the antenna =OR= the rig
connected to the dummy and the antenna connected to ground. That would be cool.

73,
--
HZ

On Mon, 13 Oct 2008 15:15:44 -0600, Hank Zoeller
wrote:

Richard Clark wrote:
Rig can be
1. open
2. grounded
3. to switched antenna

Antenna can be
1. open
2. grounded
3. to switched rig

As a refinement I'd put a dummy load on switch #1 so that the choices would be:
Rig can be:
1. Open
2. To dummy load
3. To switched antenna

The antenna switch would remain the same -- open, grounded or to switched rig.

I'd rather run my rig into a somewhat reasonable load rather than a short to
ground during the inevitable instance of forgetting to set the switch properly.

If running less than say 200 watts output then one could even use an
incandescent light bulb for the dummy load. It would presumably light up if
one were to inadvertently transmit in that configuration. So, the rig would
be at least partially protected and the operator would have some indication of
why no one is answering his CQ. Maybe a *red* light bulb?

One could also physically (not electrically) parallel the switches so there
were only two configurations. The rig connected to the antenna =OR= the rig
connected to the dummy and the antenna connected to ground. That would be cool.

Hi Hank,

Sounds like good advances toward full use of the two switches.

73's
Richard Clark, KB7QHC

"Gary Pewitt" wrote in message
...
Here's a simple question. I want to connect my transceiver to several
antennas using 450 ohm ladder line and a balanced tuner. I found a
couple of small double pole double throw knife switches for the ladder
line. There are only two ways to hook these up. I can hook the tuner
output to the center with the ground on the bottom and the antenna on
the top connectors. This will allow me to connect the transceiver to
the antenna or to ground. The second way is to connect the
transceiver to the top contacts, the antenna to the center, and ground
to the bottom contacts. This will let me connect the antenna to the
radio or to ground. Is it better to ground the radio and let the
antenna float? Or to ground the antenna and let the radio float?
Of course if I leave the switch handle sticking straight up nothing is
connected to anything.
I am inclined to think grounding the antenna is better but I have been
wrong before.

Thanks and 73 Gary N9ZSV

If you have a real problem with lightning in your area, do some reading on
the situation. You might drastically redesign your grounding situation. The
grounding should be tied together at the service entrance, so the antenna
entrance should be near there and all tied together with low resistance to
ground. This means the tuner should be there too or at the antenna The
radio should be grounded to the entrance also. It is important that all
grounding should be done outside the building rather than through the floor.
That would bring the major current of a strike through your house. There
are ARRL tis documents on the subject and a bunch of others.