[ICOM] IC-756PROIII No Transmit

[mikea]

On Tue, Mar 24, 2009 at 04:29:08PM +0000, Alex wrote:
> > Guys: Products like the Burghardt BEV-756 are designed to serve as a front end
> > saver for those hams who may not understand that one cannot safely transmit on
> > one antenna and leave another one such as a Beverage receive antenna  still
> > connected to the receiver. I am amazed at the number of hams that I know who may 
> > do this without realizing the possibility of damage to the radio.
> 
> What should amaze you more is that manufacturer's of radios don't
> build in this kind of front end protection while they do include
> protective measures to prevent a PA from transmitting into a bad load.
> I'm not surprised that some hams come to expect such a protection
> to be there, especially since it's such a well understood problem
> and has been around since RX-only antenna options have been added to
> radios. Of course someone's going to say that it would make a rig more
> expensive...

Amen. I find it difficult to see that another dollar or two in the cost
of a top-flight rig would dissuade a great many folks, and it would
drop P(failure) nicely. My R-390, R-390A, and R-1051 receivers all have
such protection, and I believe that my Racal 6217E, DEBEG 2000, and
ITT/Mackay 3020E also do. It's not rocket science: just sense the input
signal and trip a relay or drive a transistor to disconnect the rest of
the front-end from the antenna while there's an overload coming in, or 
have a low-voltage Ne lamp across the input. 

Increased complexity? Yes. Increased cost? Yes, again. Would I prefer 
a rig with such protection to one without? You Betcha. 

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin