[Elecraft] Antenna switches

[Jim N7US]

That switch is rated at 2500W PEP but only 1000W CW.  Has anyone used them
at 1500W CW or RTTY?

73, Jim N7US

-----Original Message-----

Let's add some real numbers.

I have a mechanical A/B switch DIAWA Model CS-201.  Fairly inexpensive.
Internally, it has a cavity design to provide isolation between the ports.

Using an HP signal generator and an HP-3586C selective level meter the
isolation of the switch was measured.  The used port was terminated in a
50 ohm dummy load.  The "open" port went into the selective level meter
which had a input Z of 50 ohms.  The HP-3586C can measure RF power levels
accurately within a few tenths of a dBm.  Differences are at least as
accurate.

Here are some numbers:
160M/80M 80 dB isolation
20M      69 dB isolation
10M      60 dB isolation
6M (by extrapolation) 46 dB.
YMMV

Note the frequency dependence.

This switch provides the 40 dB isolation necessary.

I have no connection with DIAWA but was interested in this topic.

I suspect there is some real junk out there.  Obtaining 60+ dB isolation
isn't easy.

The slide switch "designs" described by some are likely in that junk
category.

If in doubt measure.  You have two rigs and an S meter.  Input .1 or 1 watt
to the switch terminated as above and look at the S meter for the rig on the
open port. Scale the results to 100 W. If it shows S9+80 dB or less, you are
likely OK.  Keep in mind many S meters are horribly inaccurate.  They tend
to be too generous at around S9.

Not knowing could be expensive.

73 de Brian/K3KO