[Skimmertalk] Antenna for Quicksilver Receiver

[H Lawrence Serra]

Mack-

I now use an SDR-IQ (and formerly used my Racal 6790) to feed the Skimmer on an independent all-band antenna, which is very close to my xmit antennas (~50ft). Running 500W QSK I fried the front end FETs on the 6790 even with its internal 200usec T/R relay, which couldn't keep up with the cycling rate of fast QSK keying of the transmitters. 

So decided to add an outboard T/R switch which disconnects and grounds the ANT input to the Skimmer's SDR-IQ upon the first key-down of either SO2R xmtr, then keeps the ANT ckt grounded for an adjustable "hang-time" (0-15 secs, usually ~4 secs) while the xmtrs are sending the QSO exchange or calling CQ. [Circuit for hang-time T/R switch attached.]

I also use two pairs of cross-polarized 1N914 diodes across the SDR-IQ's ANT input, and a #49 pilot bulb in a socket in series with the ANT's center conductor. (#49 bulbs are a lot cheaper to replace than front end FETs; I just fried and replaced a bulb yesterday.)

Anyway, all this might be overkill, but it works like a charm, and I am confident I won't have to replace anymore Skimmer radios or front-ends.

73, Larry N6NC





________________________________
From: Mack <mccormick_mack at hotmail.com>
To: skimmertalk at contesting.com; dxatlas_group at yahoogroups.com
Sent: Mon, February 15, 2010 12:00:02 PM
Subject: [Skimmertalk] Antenna for Quicksilver Receiver

I plan to add a Quicksilver receiver to my station set up this week for
multi-band use with CWSkimmer Server. 

1. What antenna are you using? Height?

2. Is the antenna dedicated to the Quicksilver or are your sharing the
antenna with a transmit antenna?

3. If you're sharing the antenna with a transmit antenna is it sufficient to
place a receiver protector on the front end of the Quicksilver and to short
the antenna input to ground via a relay during keying? Of course, I
understand there are many variables here and will measure the input voltage
to the Quicksilver to ensure I'm not exceeding 0.3mv. A mechanical relay
error that would send 1.5kw into the input of the receiver does make me
shudder.

I plan to use this limiter on the input to the receiver:
http://www.iceradioproducts.com/reconly.html#rflimiter 

73,

Mack de WB4MAK
http://www.nfarl.org
http://www.sedxc.org


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