[1000mp] Relay thing..deaf receiver

[Thomas Otterbein]

Hello, 

I watch the thread long time and I had also the described problems of the 
RX muting with my MkV in the past. 
My transceiver (FT1000MP MkV Field) were two times at the Yaesu repair shop 
in the Netherlands. They exchanged the relays RL1002 and RL1005 at the
RF-Unit and did some modification (as they described in the 
repair report).  Unfortunately I couldn't get any information what kind of 
modification they did. 

In the meantime I read several articles about electrostatic and thunder 
storms close to antenna systems. 

With the knowledge which voltage loads can occure during thunderstorms and 
caused by electrostatic charges at antenna systems I now always disconnect 
the antenna cables from the radio when I leave the shack. 
And since that time I had now more than 1,5  years no problems with the 
mentioned relays and RX muting anymore. Not one single time the RX was muted

due to relay problems. 

Beside this I read also an interesting article in a German ham magazine 
about coax cable and its electrical behaviour as a capacitor. 
The author wrote that he measured at a open coax feed line of a antenna 
system  (without earthing) after several days thousands of volts capacity. 
When you connect in this case the coax direct to the transceiver the ´stored

voltage´ will be grounded over the radio
and the related relays. 
I think no good conditions for the front end to survive :-). 

Be careful, not all coax switches connect the unused antenna port to
ground. For example the DIAMOND antenna switches CX-310, which I use, didn't

ground the unused port. 

Some Balun/UnUn systems are DC grounded and with this the above described 
´earthing´ will not happen. But for example direct feeded dipoles will act 
with its coax line as a big capacitor (for example RG213 101 pf/meter). 

With all this information I disconnect now always the feed line from the 
transceivers and ground it to avoid high voltage groundings over the radio. 
And up to know it helps and I hope it will keep it like it is :-). 


In my humble opinion the mentioned relays at the RF-unit are too sensitive. 
And when I see how many OMs wrote about their experience it is not a 
individual case but a common problem besides this in other respects fine 
transceiver. 

I would therefore recommend all MkV user, disconnect the antennas from the 
transceiver when not used and ground the coax feed line. 


73 
Thomas 
DG8FBV 
--- 
www.dg8fbv.de