Re: Center-fed antennas
Posted by
Joe Subich, W4TV-4 on
Oct 10, 2019; 11:57pm
URL: http://elecraft.85.s1.nabble.com/KX2-Antenna-Curiosity-tp7655612p7655638.html
The one "multiband" antenna one can use in a multi-transmitter
configuration is the flat-top with open wire feeders and a
*Link coupled* tuner. The link coupled tuner is a bandpass filter
that significantly reduces harmonic/broadband noise just like the
"Q" of a single band antenna.
73,
... Joe, W4TV
On 2019-10-10 7:44 PM, Don Wilhelm wrote:
> Bob,
>
> Bandpass filters at each station will help a lot, but they do not have
> infinite out of band rejection.
> There is still a huge benefit with single band antennas. My club uses
> both.
>
> Last Field Day (3F operation) one station got on the air with a
> multiband vertical, and all other operators jumped on that operator to
> shut him down quickly! The multi-band antenna radiated harmonics of the
> radio. Even though the transmitter met the -43 dB harmonic required by
> the FCC, the proximity of the multiband antenna to other antennas caused
> problems (that station was not using a bandpass filter).
>
> So for Field Day multi-station operation, single band antennas, bandpass
> filters and transmitters with low phase noise are important. We were
> not able to orient the antennas end to end due to space considerations
> at the EOC site, so we had to compromise on that, which makes the other
> factors very important.
>
> I need to point out that as an experiment, a 2nd station used an antenna
> on 20 meters separated from the main 20 meters, and we were able to
> operate one on CW (K3) at the same time as the other station (Icom) used
> digital and SSB modes. We had some mutual interference, but it was
> minimal. The K3 did not interfere much with the Icom due to the K3's
> low phase noise, but the Icom did raise the background noise level on
> the K3.
>
> 73,
> Don W3FPR
>
______________________________________________________________
Elecraft mailing list
Home:
http://mailman.qth.net/mailman/listinfo/elecraftHelp:
http://mailman.qth.net/mmfaq.htmPost: mailto:
[hidden email]
This list hosted by:
http://www.qsl.netPlease help support this email list:
http://www.qsl.net/donate.htmlMessage delivered to
[hidden email]