Nowadays we have a huge amount of RF repeaters in use for several services,
like , Wi-Fi , LTE4, Data links. Microwave links, FM stations link, TV video
links.
All these systems has a receiver and a transmitter. The intermediated
frequency used can be close to few MHz depending the services. Like video.
Our HF signal can become data in these system,. A lot of this system does
not have the quality necessary, price is always a sales point, so poor
shield is very common.
SDR technology that provide long delays, and with very bad IP3 front end
are very common used on these system.
The long cables with not appropriate ground can become efficient antennas
for low bands, the common mode noise can get into the IF system and on the
receiver side and retransmitted on the transmitter side.
My point is that atmospheric plasma loops may not be the only answer for
250ms echo's. It is most unlike due the small power used during the event
observed. Manmade echo are more likely to explain the echo.
73's
JC
N4IS
repeaters, ----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Tim
Shoppa
Sent: Sunday, February 05, 2017 4:44 PM
To: on7eh <on7eh@skynet.be>
Cc: topBand List <topband@contesting.com>
Subject: Re: Topband: Echo on 160m yesterday morning
I have heard echoes of my own signal under some circumstances too. More
often on 80M but a couple times on 160M. Often in the hour before dawn.
These echoes were also heard on other stations within a few hundred miles,
especially ones to my north.
For the 160M echoes, some stations in W1 were nearly uncopyable on my
receive antenna (K9AY) because of the echo. The echo was very similar to a
dit length and very similar in strength.
Interestingly enough, if I went to listen on my transmit antenna (Vertical),
the echo completely went away.
Tim N3QE
On Sun, Feb 5, 2017 at 4:32 AM, on7eh <on7eh@skynet.be> wrote:
> For the first time,
> I heard my echoes on topband, yesterday morning starting around 05 UTC.
> They lasted for at least 1 hour, with some OFF-periods in between.
> I had to quit at 06 UTC. (still 1 hour before surise)
>
> The echoes were loudest on the short Beverages (<60m long) heading N/S
> and NE/SW and several dB lower on the NW/SE Beverage. (about 130m long).
> The Tx setup is modest with Elecraft K3/100 and inv L at 15m height,
> sloping down to 11m.
>
> Only DX heard that morning was USA (typical condictions) so I wonder
> what else does hearing echoes indicate?
>
>
> 73,
> Michel, ON7EH
>
>
>
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