Band Switch for high power rf

[KL7OF]

I have used mostly surplus switches in the past.  those are becoming scarce and they are not up to the higher voltages and currents in use.  What is available...?  I googled and I'm not finding anything usable...I have an old Ohmite ceramic body 13 position rotary with 1/4 inch spacing between the 3/16 diameter contacts that has  more potential as the surplus stuff.. What are builders using?  I see some of the well engineered, high budget home brew transmitters using large bandswitches but details are lacking.. I am working in the 5- 7.5 kv range and as soon as I got above 5.5 kv little band switch arcs occured..the swith in use has 3/16" spacing between contacts so  it is marginal ...

[K1JJ]

Check on e-Bay every day for "rotary bandswitch," "bandswitch," "radio bandswitch."

Here's one up there now, though probably too small for your use:

https://www.ebay.com/itm/1-NOS-2-1-2-Ceramic-Rotary-Band-Switch-for-Amplifier-7-positions-2-section/313288670571?hash=item48f175bd6b:g:eNgAAOSwyARfpKQW

Ham flea markets are by far the best source of big bandswitches.   The T-368 surplus bandswitches did a good job in the past if you can find them.

I use 6" diameter or larger ceramic switches for my big rigs. You will have to eyeball it and figure out the contact spacing and potential arc paths.  Much will depend on the Q of the circuit, loading and of course the level of peak voltage, especially if plate modulated.

T

[KL7OF]

There are always plug in coils....

[Jim, W5JO]

Ameritorn is a source, a bit pricey, but the one for the AL 1200/1500 is the old Centralab Ceramic switch.  Use only the portion you need.
The Ameritron advantage is it is new. 

[W3SLK]

I always keep a 'folder' for places that advertise parts and such. I have no connection with this person nor have I purchased anything from him but you can try it as a resource.

http://www.ur4ll.net/

[KD6VXI]

I always keep a 'folder' for places that advertise parts and such. I have no connection with this person nor have I purchased anything from him but you can try it as a resource.

http://www.ur4ll.net/

I have purchased stuff from Alex, UR4LL, for a couple decades..  And have friends that have as well.  He was one of the original pioneers of the surplus Russkie stuff.  He has some nice switches as well.  They have switched multiple kilowatts with ease.

Another good thing about buying from Alex is that you are supporting doctors whom do procedures and wellness for children in the Ukraine and elsewhere.  His operation helps to fund this, and is a major reason I have supported him.  Not to mention, his prices and customer service is really hard to beat.  He sends you a tube that is damaged in shipping or doesn't work?  OK.  New tube on the way.  No, don't worry about returning it.

Also, with the cheap price of the commie vac relays, a simple rotary switch will allow you to make a killer bandswitch with vac relays.

--Shane
KD6VXI

[WA2SQQ]

MFJ sells parts and they have a few amps.

[KL7OF]

Thanks for the link to Alex....I plan to get a few hi voltage caps from him.....I solved the bandswitch problem.....I found a 23 uH roller coil in the hanger junk...I disassembled it and cleaned it up , and it works gud so far...It looks like a 2 KW coil   .Im at 4500 volts with all bands working ...I try higher voltages tomorrow.  Shane... I like those relays...some of those amp pictures are great ...Thanks for telling of you experience with Alex...

[nq5t]

A roller inductor is a good option, and no where near as hard to find as a suitable switch.

Multi-Tech Industries bought out Radio Switch back in the 90's.  They still make these high voltage ceramic RF switches, but I imagine the one-off price for a custom switch could be substantial.  It might be interesting to find out …

https://www.multi-tech-industries.com/rswitches.html