Elliott,
You may do more harm than good using a directional antenna for access to a
DX PacketCluster node. While improving the signal strength on both ends, you
may find that under certain local user conditions, you will constantly
become disconnected from excessive retries due to your packet signals
colliding with those of another station who is located in a null position of
your yagi. The vast majority of sysops recommend that omni directional
antennaes be used for best truput and frequency utilization. Being able to
"hear" every station that the node hears would provide optimal conditions
for avoiding packet collisions and subsequent retries. An omni directional
antenna is the best way to accomplish this. Since users are usually spread
out over a wide area, any antenna with various nulls in its pattern will not
hear many of the stations in the those null areas, causing packet
collisions. Your TNC will only go into transmit mode if the frequency is
apparently clear. With another user in a null area is transmitting a data
packet and you're not hearing him, your TNC sees it as if the frequency is
clear, when, in fact, it is not, resulting in a probable collision and
retries to the node from one or more of you. This can be magnified with
other users in your yagi null areas!
Suggestions would include a higher gain omni antenna such as a collinear,
lower loss feedline, higher RF power, (if the problem is YOUR signal
strength into the node), and/or, of course, getting the antenna to a higher
elevation. Another solution may be found by digipeating through another
node user who has a reliable connection. OR finally a better and higher
antenna at the DX PacketCluster node station, which you'll most likely not
have any control, except maybe by making large donations to your sysop and
hoping.
73 and Good Luck, -=Rog-K9RB=-
-----Original Message-----
From: Elliott Lawrence <edl@pacbell.net>
To: towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Thursday, July 23, 1998 1:08 PM
Subject: [TowerTalk] 2 Meter Antennas
>
>I need a small 2 meter yagi to improve the signal into a DX cluster.
>Considering the M2 2M4 4 element or 2M7 7 element. Any comments on these
>antennas would be appreciated.
>
>73
>Elliott WA6TLA
>
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>
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