Re: [amsat-bb] Yeasu 736-R Question

[Douglas Cole <n7bfs@xxxxxxxxx>]

Bruce Bostwick wrote:
> 
> >Please be careful not to change transmit modes while d/c is on! The other
> night
> >I was changing band by pushing the band button and it threw a spike up the 2
> >mtr.
> >coax. Sounds really strange, but I guess anything is possible.
> >Steve / KB8VAO
> 
> Pity there aren't any circulators/isolators for 2m .. this would be just
> the application for an isolator .. downconverter sees in the input of the
> radio, radio sees a 50 ohm dummy load.  If the IF was on 432, an isolator
> would be a little more feasible, but for this application I don't think
> it's possible.  Something to think about though ..
> 


Ok , so I am a little confused here , as there -are- vhf isolators that
will work on amatuer bands ( I am using one on my IRLP repeater) , the
only trouble I can see is they don't give you -complete- isolation (
around 30db ) so there will be a sizeable signal going back to the IF
output of the converter ...

Maybe using pin diodes to shunt the leftover rf to ground would work
....

Or in my case I just ran a couple of rx input jacks on the back of my
ft847 to the rx input on the main boards and just bypassed the main
antenna input , this to me is the best solution , though I am not sure
how do-able that is for other radios , it was nice in the '847 ......

my 2c

-- 
Douglas Cole   N7BFS
AMSAT#26182 , K2 # 544
http://www.users.qwest.net/~cdoug3
Registered Linux user # 188922
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