Topband: RX/TX Antenna decoupling, (OFF LIST)

[HAROLD SMITH JR]

Sorry to let you know that a brilliant light that was Price was dimmed on the 21st. Price is a silent key now. He will be missed.XYL  Inge

      From: Rob Atkinson <ranchorobbo at gmail.com>
 To: topband at contesting.com 
 Sent: Friday, October 6, 2017 5:15 AM
 Subject: Re: Topband: RX/TX Antenna decoupling, (OFF LIST)
   
> Thanks for sharing this info.
> Would you please provide more information on the relay model number and how
> it is wired into your system.

I used a P&B open frame relay 4PDT but a single throw will work.
What's important is that the relay use metal other than steel (or
other magnetic metal) for the RF path.  The P&B PM17DY satisfies this
requirement.  I mounted it in a plastic box and mounted UHF jacks on
the ends and ran copper strap and AWG10 stranded to the relay, using
the AWG10 for the center conductor.  I used two poles for the center
and two for the cable shield.  On rx the relay is open and the
inverted L is disconnected from the shack and common mode RF prevented
from continuing to the shack.  The plastic box is important for this
-- a typical metal box would allow the shield RF to continue from the
UHF jack flanges around the relay at all times.  The relay I used has
a 24 v. coil because my T/R sequencing system runs on a 24 v. DC
supply.  This as all antenna relays should be used with a sequencer to
avoid hot switching.  Obviously this is not a solution if one desires
QSK.  In that case a faster switch is needed.

73

Rob
K5UJ
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