[Icom] Coax Switches Revisited

[Lefczik, Larry D]

100Watts - 50 dB = 0.001Watts  1mW into the front end of a receiver.  Scary?

 
+ Frank, I have run those test on the Diawa cavity switches in 
+ the past.  If
+ memory serves, they provide about 50db of isolation per port 
+ to about 300
+ mhz and about 40db above that.  Dave
+ 
+ 
+ > >
+ > >Hi Folks,
+ > >
+ > >Well on Thursday I decided to start doing some tests on my 
+ XXX brand coax
+ > >switches as to the amount of isolation between the 
+ selected rig and the
+ > >other 5 "grounded" positions.  I do have external grounds 
+ run to the case
+ > >of the switches.
+ > >
+ > >I used some very small wire and a little pickup coil run 
+ to the outside
+ the
+ > >box to a small 12 volt light bulb. When running 100 watts 
+ to the dummy
+ > >load, the bulb would light at about 50 to 60 % of it's 
+ normal output,
+ > >interesting.
+ > >
+ > >Next I unhooked the other 5 rigs from the switch and 
+ hooked the bulb to
+ one
+ > >of the unused coax connectors and fired up a rig at 100 
+ watts in RTTY to
+ > >the dummy. Guess what? the bulb blew.., Burned out, toast etc.
+ > >
+ > >So, I have to wonder what is this doing to the other 5 
+ rigs hooked to the
+ > >switch even though the rigs were off?  I think I know now 
+ why my Icom PCR
+ > >1000 had the front end fried on it.
+ > >
+ > >So, major changes took place based on these tests.
+ > >
+ > >I removed the switches and went back to my old method of 
+ isolation and
+ rig
+ > >switching by using feed thru bulkhead coax connectors 
+ mounted on a panel
+ > >with the various rigs hooked to the back side and then the antenna
+ > >selection just hooks to whatever rig I wish to use at the 
+ time. Simple
+ but
+ > >I feel it is whole lot better and safer. I will update the 
+ pictures on my
+ > >web page later tonight.
+ > >
+ > >This was my test run under controlled conditions and your 
+ mileage may
+ > >differ.
+ > >
+ > >73
+