The AM Forum

I am growing tired of switching my open wire line from each of my WRL stations. 

one station is a Globe Champion 300 with my new Globe Matcher SR antenna tuner. 

The second station is my Globe king 500C with the johnson KW matchbox.

My open wire line enters the wall and runs to the KW. I would like to stack the Globe matcher ontop of the KW and find a knife switch to switch the feedline from one tuner and station to the other.

I searched around and cant seem to find anything that will work. I need one input and two ouputs. 

By the way.. This I got the Globe matcher SR. today and it is in fact brand new in the original carton!  Its rated for 600 watts AM phone input power but its small size tells me not to run it behind the King 500C. Even though the manual states you can.  I have decided to not take a chance and to just run it with the Champion. At 220 watts output, I wont have any worries!


Clark

how about one of these?

http://cgi.ebay.com/ANTIQUE-TRUMBULL-BATTERY-SWITCH-PORCELAIN-KNIFE-SWITCH_W0QQitemZ400062113752QQcmdZViewItemQQptZArchitectural_Garden?hash=item5d258f67d8&_trksid=p3286.c0.m14&_trkparms=65%3A1%7C66%3A3%7C39%3A1%7C293%3A1%7C294%3A100

Check out this ebay switch, ebay item # 220453388094.

Also there are a lot of knife switched on the link below.
http://www.shopwiki.com/KNIFE+SWITCH+DOUBLE+POLE+DOUBLE+THROW

Al, n7ioh

NICE!  Thats exactly what I need. This way, I can put the switch in the middle for total disconnect! 

Clark

Al and Clark,

This triple pole double throw switch is the best in my opinion. You can use the third pole to switch a DC ground for a light to show you at the operating position which TX is hot. AND it will handle the Globe King 500 output more dependably.

Mike

The double throw type is nice for grounding as well, one position being to the rig and the other to ground when you're not around. Not sure how you can best accomplish that otherwise, either using alligator clips or placing yet another switch in the line for grounding.

I like the light idea, Mike. Also a good reminder of whether or not the ant has been grounded.

When I search ebay, I get lists for Pocket knifes.  Only a few smatterings of Switches. I see the old Ceramic type. The other links are for boxes of 10 or 20. LOL

Mike, My antenna is already grounded through coils. I just need to switch from one station to another.  So double pole and double throw right?

Clark

Yes Clark, a DPDT is all you need now. This switch

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220453388094&ru=http%3A%2F%2Fshop.ebay.com%3A80%2F%3F_from%3DR40%26_trksid%3Dm38%26_nkw%3D220453388094%26_fvi%3D1&_rdc=1 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220453388094&ru=http%3A%2F%2Fshop.ebay.com%3A80%2F%3F_from%3DR40%26_trksid%3Dm38%26_nkw%3D220453388094%26_fvi%3D1&_rdc=1)

will give you the DPDT switch you need with the power handling potential of a kilowatt DC or more plus an extra SPDT for a light or whatever.

Todd has a point in my opinion. I use the same inductors you use for static and they ARE a direct DC path to ground but I think a direct, high current path to ground during a storm is better. I add jumpers direct to earth when storms are in the forecast.

Maybe reconsider the spark plugs for the high current arc path and the switch above for inside the shack. You'll be styling in Old Buzzard Fashion.

Mike

Clark, when you do a search for say a knife switch put quote marks around it like this, "knife switch".  Whether on ebay or just doing a search on Google it will look for that phrase exactly rather than knife and switch separately.  You can also use several phrases in a search like, "knife switch""Johnson Viking Ranger". 

Al n7ioh

The one that Mike gave a link for is what you need OR try Surplus Sales of Nebraska

Fred

Are DPDT knife switches another common every-day item that has now been "discontinued"?

Last time I  needed one, probably 20 years ago, I could have bought all I wanted at the local electrical supplier.

Probably "too Dangerous" for the average Joe,

If you weren't carefull you could get across the blades while switching something and get a nasty shock and sue someone...

I like that Signal corps one!

Thanks for the tip on the searching. I should have known that.


I cant find any new made knife switches that are up to the task. I have found a slew of ones marketed towards Science labs at schools. These are small and made for low voltage DC. 

Thanks again guys!

Clark

I bought two of those Signal Corps jobs from that guy, they are mint NOS and totally FB for the task.  Bid on! 8)

Clark, would one of these do?

I have collected quite a few smallish ones, maybe 2.5"x5" size. I don't need all of them, but had to take the "lot" to get what I needed. They are some kind of black bakelite or hard plastic. The center "off" position has a detent. Anyone ever seen this kind?

I considered using them for:

1.) moving the "C" from radio to antenna side of the "L" in the balanced-balanced tuna

2.) earthing the tuner input indoors (in conjunction with disconnecting and grounding it outdoors with a much bigger switch)

Can anyone guess the current handling per pole, and, if mounted on an insulating sheet, the voltage rating?

can handle 1KW CW or 4KW PEP (12.6 peak amps/632 peak volts @ 50 Ohms)? (also might like to use for off the air tests) haha maybe that's too much..

I would think that would work just fine.  The champion is 220 out.  The King is 375 out.   The Slop bucket station is 1500.  Not sure that it will handle the 4-400 twins.   But I dont think my 18G open wire line will either..!!! :o

PM me your address and I will send it one you.