Ian White G/GM3SEK wrote:
Brian Kelly wrote:

.. . . .

I need some sort of relays which can handle 2kV of HF RF at 2 amps.
Single pole NO non-latching reed switches would do the job.

I know I can use surplus vacuum relays but at $35-40 a pop that ain't
gonna happen.

Any and all suggestions will be appreciated.

By coincidence, I was reading an electronics mag over breakfast today,
and saw this press release:

"Crydom has launched a high performance miniature reed relay boosting
carry currents by 33%. Fitting a full electrostatic copper screen that
completely enshrouds the relay coil, a reduction in power loss is
achieved. Lower loss means lower self heating - enabling an increase
in carry currents to an industry leading 4A RMS at 30MHz from the
miniature 30mm x 10mm package.

"The 6 Series is designed for next generation HF antenna couplers and
filter circuits where improved RF performance and higher packing
densities are required.

"The hermetically sealed high vacuum reed switch will isolate 3kV
minimum (DC or RF peak) making it suitable for a range of Test Equipment
and Electromedical applications where high voltage, high current pulses
are generated."

They sound like they'd definitely do the job but so far I can't find a
U.S. source for them.

Without necessarily endorsing that particular product, there are a few
interesting points:

* Switching in HF antenna couplers and filters is now a recognized
market.

* Reed relays can handle this kind of service.

Exactly. They're showing up everywhere in recently-designed ham
equipment - to the 2kW level and beyond. Big amps, big autotuners, etc.


In prior times the coax could be remotely switched but the only relays
which could handle high RF voltages were pricey vacuum relays. It's the
recent advent of these inexpensive new type reed relays which led me to
reconsider using end-fed half-wave verticals.

* Coupling into the coil can be a problem, which may suggest making your
own. Crydom use a shielded coil, and an alternative idea ISTR is to wrap
the glass relay tube in foil instead of the coil. (In both cases the
shielding would need to be overlapping but non-shorting.) Which is the
better would depend on the application, and how much shunt capacitance
it can tolerate.

I don't understand the shielding/loss problem. I wouldn't be using
these relays inside equipment where shielding as such might matter. How
how significant are these losses? I'm switching the bottom ends of more
or less resonant wires from wire to wire and from tuner to tuner in
some arramgement or another TBD. All of it out the yard where I hope I
radiate as much RF as possible.

More details and a data sheet at:
http://www.crydom.co.uk/Webpages/arc...d_rf_relay.htm

Nice specs, I'll continue the hunt for a source.

--
73 from Ian G/GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Thanks Ian.

w3rv