Topband: Protecting RX input & FK8CP this morning

[Jeff Maass]

> -----Original Message-----
> From: topband-bounces at contesting.com 
> [mailto:topband-bounces at contesting.com] On Behalf Of Paul Kelley N1BUG
> Sent: Wednesday, April 04, 2007 9:42 AM
> To: Topband
> Subject: Topband: Protecting RX input & FK8CP this morning
> 
> Greetings fellow Topbanders,
> 
> When my rig comes back from the repair shop I want to modify 
> it to add a RX antenna input. My current method of selecting 
> RX antennas is awkward and may have resulted in the damage 
> the rig is now at the shop for! I had a relay glitch just 
> prior to the rig's demise. Some of my Beverages run quite 
> close to the transmit antennas and I am concerned about 
> damage to the receiver from excessive RF levels while 
> transmitting. I thought about adding a relay to disconnect 
> and/or ground whatever antenna is connected to the RX input 
> during transmit, but since I will also be working on station 
> mods to allow QSK I am interested in keeping the number of 
> relays to a minimum. 
> Are there other ways of protecting the receiver? Or is the 
> relay my best bet?
> 
> 73,
> Paul N1BUG
> _______________________________________________


G'day Paul:

An I.C.E. #196 or #197 "RF Limitor / receiver protector" is one option, which requires no
no power and no switching on transmit - just plug it into the RX antenna line.
http://www.iceradioproducts.com/reconly.html

Not a good solution in a M/S, M/2, or M/M contest station, though - it will block the
signal to the RX input when any signal exceeds it's limits on the RX antenna, even on the
other HF bands! 

We bought four of the ICE #196 devices for PJ2T in November, but cannot use them in that
station since we are almost always multi-transmitter in contests. They test out fine,
working as advertised, though. I'll be selling the ones now at PJ2T when they come back to
the USA next week. 

Other options, which require power and a switching line from the transmitter/transceiver
on transmit, are the KD9SV "Front End Saver" (http://johnjeanantiqueradio.com/gary.htm,
available at http://www.radio-ware.com/) and K9AY's "RIP-1" (which was available at Array
Solutions / WX0B, but may no longer be available), both of which work well.

Or, you can homebrew a simple (fast) relay to switch the RX antenna line to the radio.

73,  Jeff  K8ND