If they were using 1975-vintage radios, with vacuum tube front ends, I'm
not surprised there was no damage. And if there was damage, I wonder if
the typical, non-contester, Field Day operator would even notice !
Operating with a "general purpose" radio club, how many times have we
walked up to a Field Day operator, on what should be a wide-open band,
only to discover he/she as made no QSO's in the last hour ? We snoop
around, and discover obvious issue(s).
73,
Steve, N2IC
On 06/17/2015 06:49 AM, Joe wrote:
I'm curious,
This conversation has been interesting for sure. But I wonder if the
risk of damage has or is being exaggerated some. Reason thinking this is
for one thing. What is gonna happen in a little over a week. Field Day.
Field Day, pushes the damage potential to the extreme far more than SO2R
could ever be. And in many instances filters are not even an option for
protection. As in the case of a say 40 meter phone station, CW station,
and ex Novice Station ( Now the GOTA Station ) all on 40 meters at the
same time.
Yet I have been doing Field Day since 1975, from simple 1A efforts to
2A or 5A and even up to once a 12A group. Yet I have not in my mind
ever known of any damage that has ever happened to any of the rigs. Even
one group one year was a 3 A Operation and all they had were multi band
verticals for each station and they were all mounted on the same barb
wire fence than was their ground system. and the 3 antennas were at the
most maybe 100 feet apart MAX. Granted in this setup they were not able
to operate all 3 on the same band, the overload desence was terrible.
sounded like a big vacuum cleaner on the band sucking up all the
signals, but no damage happened.
Hmmmm?
Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 6/16/2015 5:14 PM, Jeff AC0C wrote:
The amount of work a guy may want to put into checking out the setup
for isolation is in direct proportion to the cost of getting a
potentially expensive RX repaired. My view is that until you have
TESTED to BE SURE the isolation exists, you have to assume it's going
to fry gear.
And don't let the thought that "I'm only running 100W" be of any
consideration. That's +50 dBm and you want to be very much under +20
dBm to avoid damage - and less than that in some cases. I think W2VJN
recommends 0 dBm as the damage threshold target. That means you need
30-50 dB of isolation, on every band and directional combo - something
which takes time to check out. The isolation is easy to achieve with
natural coupling loss and a stub.
You really will probably not be happy if you just try it, trusting
luck alone, only to find out luck ends up against you.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
-----Original Message----- From: Jeff Stai
Sent: Tuesday, June 16, 2015 12:31 PM
To: Mike Smith VE9AA
Cc: cq-contest
Subject: Re: [CQ-Contest] LP SO2R with no filters?
On Mon, Jun 15, 2015 at 2:53 PM, Mike Smith VE9AA <ve9aa@nbnet.nb.ca>
wrote:
Has anyone ever done SO2R with no bandpass filters?
Buy the W2VJN book from Inrad. It will explain everything:
http://www.qth.com/inrad/book.htm
But in a nutshell, just try it. It sounds like you have both
horizontal and
vertical antennas, which will give you 20dB of separation at the outset.
That could very well be enough for your conditions. If you need more,
stub
filters can be very effective for the cost of some scrap coax.
73 jeff wk6i
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