[1000mp] (Non) Switching of RX Ant (was RX Ant Out)

[Barry N1EU]

N4ZR: "It appears that RL-1002 in the Mark 5 opens the RX input line to 
protect the receiver from RF coming in on a separate receive antenna when 
the transceiver itself is transmitting.  The overview also says that the 
Mark 5 incorporates a surge suppressor on the RX antenna circuit -- looking 
at the schematic, it appears that there's a small inductor in series with a 
100-ohm resistor to ground which presumably does this job.  It would be 
interesting to know from someone more technically qualified than I am 
whether this surge suppressor affords any useful protection for the front 
end from strong signals originating in another transmitter, for example in 
an SO2R setup."

I'm not expert at reading schematics, especially the MP schematics, but I 
believe the MP circuit is slightly different. The RX ANT IN goes through 
RL-1001, which is controlled by the RX ANT switch on the front panel.  It 
then goes through RL-1002/3 which are the switchable attenuators, and on to 
the front end.  It does not appear that the RX ANT IN is turned off during 
transmit.  Yikes!  Perhaps someone more expert can take a look and comment.

I'm also not sure that an inductor to ground through 100 ohms provides much 
surge suppression.  Does it?

73,

Barry N1EU
www.albany.net/~bg









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