Topband: LU5OM update (29 day reception report, plus more)

Don Kirk wd8dsb at
Fri Aug 11 08:59:27 EDT 2017

Mistake on my math,

I should have said I could copy him 26 out of the 29 days, I could just
detect him 1 day but not copy him, and then the remaining 2 days I did not
listen for him.

Don (wd8dsb)

On Fri, Aug 11, 2017 at 8:55 AM, Don Kirk <wd8dsb at> wrote:

> This is a follow up to my post about a month ago regarding how well I
> heard Manuel (LU5OM) when he was using a dipole (mounted as an inverted
> vee) on 160 meters.  Since then I have made a point of getting up everyday
> (typically 5 am EDT) to listen for Manuel, and to spot him if and when I
> hear him.
> The main reason for this post is to say how amazed I/we have been that out
> of the last 29 days, I have been able to hear Manuel each day with a few
> exceptions (25 days I could copy him, 1 day he was faint but not really
> able to copy him and on the remaining 2 days I did not try to copy him
> because one day he was not on, and the other day I had a bad lightning
> storm).  It's like clock work that I turn the radio on, and there he is but
> sometimes faint (I would have never thought this possible).  Also I might
> mention that my RX antenna (pennant that's 51.6% the size of a full size
> pennant) is nothing to brag about, but it's definitely better than my TX
> antenna (my RX antenna typically has an approximate 2dB signal to noise
> level advantage for this long haul stuff).
> The main point I would like to make with this post is that during the 29
> day period it has not been like a open or closed propagation situation, but
> rather slightly better or poorer propagation regarding signal strength each
> day.  (Note: 5am EDT (0900 UTC) was about 1.5 hours before my sunrise, and
> just as long if not longer before Manuels sunrise).
> Also very early on during this 29 day period Manuel changed his feedline
> over to open wire feedline which allows him to switch his TX antenna from
> the inverted vee configuration to basically a top loaded vertical (what he
> has been calling a Marconi Tee).  Same antenna with the two feeder wires
> tied together at the output of his antenna tuner.
> In all honestly the dipole has almost always been as good if not better
> than the Marconi Tee configuration (often very similar results and with
> static crashes very hard to put firm signal strength numbers on each for an
> exact comparison).
> The dipole (inverted vee) also provides a lower receive noise level for
> Manuel, and therefore this is typically his configuration of choice.  I did
> some quick modeling, and the inverted vee configuration definitely does not
> hear well at low elevation angles, and this might be why the RX noise level
> is lower than when this antenna is in the Marconi Tee configuration when
> exposed to Manuels high noise level environment.
> Note: Modeling suggests that above an approximate elevation angle of 35
> degrees Manuels dipole (inv-vee) would have a gain advantage over his
> Marconi Tee configuration whereas below 35 degrees the Marconi Tee
> configuration should be better (I modeled his Marconi Tee using 4 full size
> elevated sloping radials to keep things simple, whereas Manuel is using
> buried ground radials).
> Note: Manuel runs 500 watts output power.
> Manuel apologizes for not hearing as well as he can be heard, and he is
> currently working on some different RX antenna configurations with hopes of
> improving his receive performance.
> Just FYI, and 73.
> Don (wd8dsb)

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