[1000mp] RX antenna port

[Tod - MN]

> In my case, after studying the 
> FT-1000 MkV Field's schematic and querying Yaesu Tech 
> Support, it was verified that during transmit ALL receive 
> inputs are completely disconnected & attenuated.


I am in MN and my FT1000MP service manual is in ID. However, I thought that
I had done a careful job of checking the schematic of the two TX/RX inputs
(ANT A & ANT B) and the RX input located on the rear of the radio. When I
finished my examination I immediately purchased a Front End Saver (FES). I
wish I could say I never make mistakes, but I can't. I may simply have
thought there was a chance for disaster where none exists.

Either I misread the schematic for the FT1000MP, the comparable circuits in
the Field and the MP are different or you and Yaseu's Tech support have made
an error. 

I do recall that there were relays that might have grounded the RX and
unused ANT A or ANT B signals. BUT, if so, the grounding took place after
the signal had traveled through various transformers. If you are quite
certain that your RX input voltage is so trivial that it will not harm these
transformers I suppose there is only a moderate risk. 

I recall that as an exercise in preparation for building an SO2R station I
measured some of the voltage on various antenna feed lines when transmitting
on a different one. When I injected less than 100 watts into some of the
antennas the voltages on the unused feed lines measured in volts, not
millivolts. (I used an HP RF millivoltmeter on its highest scale).

Maybe it is just a problem peculiar to my QTH and your setup will not have
such high voltages coming into the radio on the RX antenna(s). I am sure the
Yaesu Tech will not repair your radio for free and pay shipping both ways if
he was wrong. Be sure to test your RX arrangement during the non-contest
season so if a repair is needed it will not impair your serious operating.


Tod, KØTO