Topband: C21MM

Wed Oct 23 22:32:38 EDT 2024

I did get thru this morning at 1104 utc, after calling for quite a while.
Good thing the weather is cool this time of year or maybe the 4sq would
have melted.  Signals went from -20 to as high as -4 and I squeaked out a
reply on the peak. He worked a few JA;s but I never saw any other NA in the
log then.  No shortage of stations calling.

On Wed, Oct 23, 2024 at 4:42 PM Michael Tope <W4EF at dellroy.com> wrote:

> This is an excerpt from the news report from C21MM website dated Oct 18,
> 2024 (https://c21mm.mydx.de/?News):
>
>       "We erected two 22m Spiderbeam fiberglass poles for 160 and 80m
>     verticals with one elevated radial. For 40m and 30m we use (rhombic)
>     loops with 50 Ω impedance and on 60m we use another vertical with
>     one elevated radial. DL8LAS and DL6KAC installed a DHDL receiving
>     antenna. This helps against the very high atmospheric noise (up to
>     S9). Fortunately, we do not have a lot of manmade noise at both
>     QTHs. Regarding the lowbands, we are very satisfied with the antenna
>     performance from 80m to 30m. On 160m we didn’t hear any station
>     until now."
>
>
> This feels like a long shot, but how sensitive is FT8 decoding to
> receiver settings in a high tropical QRN environment? I don't operate
> FT8 too much and I live in Southern California, so I really don't have
> any experience using FT8 in the presence of strong random bursts of
> noise. Does AGC pumping from static bursts clobber FT8? Is reducing RF
> gain and increasing AF gain the right approach?
>
> 73, Mike W4EF........................
>
>
>
> On 10/21/2024 1:34 PM, GEORGE WALLNER wrote:
> > Low band noise on DXpeditions:
> > It is easy tothink that going to a small island you will escape the
> > noise of modern "civilization". Far from it!
> >
> > If the islandhas some population, they will be using generators, solar
> > panels, inverters and electronics of the cheapest kind, with zero or
> > verylittle filtering. In one place, the TX vertical was picking up the
> > noise of the solar plant of a village (pop.300) from 1.5 miles!
> > Elsewhere, the DXpedition brings its own noise sources: generators
> > (especially invertergenerators), computers, switch node wall-warts,
> > inverters and so on.
> > Unless they the station is very close to the water, grounding will be
> > difficult asmany islands have very poor ground (coral rubble and
> > sand). And unlike with a home station, there isn't enough time tohunt
> > down, filter and eliminate all the noise sources. If it is a tropical
> > island south of the equator, the TS noise fromthe Inter Tropical
> > Convergence Zone (ITCZ) and then after about 10:00 Z, the TS noise
> > emanating from Papua NewGuinea/Indonesia will add to the local noise.
> > At all our recent DXpeditions (VP6A, E51D, K8R, T32JV, FW7JV and N5J)
> > noise was the biggestissue on TB. We spent precious hours and days,
> > hunting down sources and filtering them. There are many things that
> > can be done,including placing the generators at a distance, grounding
> > them and filtering the power cables, etc. Grounding all thestation
> > equipment also helps. Installing clamp-on ferrites or pre-made common
> > chokes can reduce the noise radiated bycables and the noise carried to
> > the antenna on the outside of the coax shields. You can go on like
> > that ... until you find that theDXpedition is over and it is time go
> > pull it all apart... without the noise being completely eliminated.
> > What I've learned is that, apart from good basic noise reduction
> > practices at the station, a good RX antennaplaced at a substantial
> > distance is the best and the most "time-effective" way to improve
> > reception on TB. TheDXpedition that seriously wants to work CW on TB
> > (and most promise) should prepare in advance and carry all the
> > material needed toinstall an RX antenna on the second day. (On the
> > first day you are working the big guns... buteven then.) A flag at 500
> > to 1000 feet from the nearest antenna and the station, fed via a well
> > choked coax(check Jim, K9YC's excellent write up on chokes at
> > http://k9yc.com/2018Cookbook.pdf ) will be often sufficient. It will
> > be much better with a remote low-noise pre-amp. A DHDL will be even
> > better but it is a verylow gain antenna and a low noise remote pre-amp
> > at the antenna is a MUST! All that should be prepared in advance, not
> > jerry-rigged on site
> > from available bits and pieces.
> > If you do it right, you will get emails like this:
> > "...incredible ears on E5-N, this morning, at 1107 UTC, just before
> > local SR, I worked E51D QRP, using a "nothing special" Inv-L. "
> > It wasn't the ears, which are not what they used to be. It was a 50
> > foot long DHDL pointing NE with a low-noise pre-amp, at the end of
> > 1000 feet of quad-shield coax with three chokes, grounded at two
> > points, feeding a Flex 6700 via the RX ANT port. That's all.
> > 73,
> > George
> >
> >
> >
> >
> >
> >
> >
> > On Mon, 21 Oct 2024 01:47:59-0700 Michael Tope  wrote:
> >> C21MM has been in solid for well over 1.5 hours on FT8 tonight and
> >> it's stillearly. They were loud enough at times (at least on my end)
> >> for a CW QSO, but they didn't decode my signal on FT8 untiltheir
> >> signal peaked up to R=0, whereas on this end I was decoding solidly
> >> down to R=-20. Clearly they have some receivechallenges. The DHDL
> >> antenna that C21MM plans to use for receive has been employed by
> >> AA7JV on some of his expeditions,so it's got a proven track record.
> >> Perhaps there is a storm that is very close to them causing unusually
> >> high QRN.
> >>
> >> I need to go to bed, today is a work day 🙁
> >>
> >> 73, Mike W4EF.................
> >>
> >> On 10/20/2024 6:13 PM, Wes Stewart via Topband wrote:
> >>
> >>>  The realities aboutsome of these DXpedtions is that they are
> >>> organized by Europeans and favor working EU. Take the just concluded
> >>> (if theykept to schedule) PX0FF expedition.  The ops were all
> >>> Europeans and >60% of their Qs were with EU and only 21%were with
> >>> NA.  They didn't even operate 160 CW.  They made 1046 FT8 QSOs on
> >>> 160 out of >150,000 total.
> >>>
> >>> 8R7X was another one with EU 54% and NA 31%.  Of course propagation
> >>> favored EU, but they were activelong enough that I worked them on
> >>> both 160 CW and FT8 as well as 22 other band/modes.Ditto A8OK that I
> >>> worked on 33 band/modes, none on topband.  EU 64%, NA 19%.I'm not
> >>> trying to disparage our EU friends, I'm just pointing out the numbers.
> >>> C21MM will be QRV for at leastanother week.  So far they haven't
> >>> made any topband CW contacts and only 6 with NA presumably on FT8.
> >>> Theyclaim to have installed an RX antenna, but have high noise.  So
> >>> we shall see, but I'm not holding my breath. To their credit they
> >>> have worked about the same number of CW and FT8 Qs and a few on
> >>> RTTY, three of them mine.
> >>> AA7JV is a dedicated 160 man, who will put in the hours needed.
> >>> These other guys are not so motivated and want torun up their Q
> >>> count by working the most productive bands, or by turning on the FT8
> >>> robots.Wes  N7WS
> >>>
> >>>
> >>>
> >>>     On Sunday, October 20, 2024 at 12:11:54 PMMST, Jim Brown
> >>> <jim at audiosystemsgroup.com> wrote:    On 10/20/2024 11:14 AM, Steve
> >>> Harrison wrote:
> >>>> If possible, please spend some timeattempting to work some North
> >>>> American stations on *160 and/or 80m **CW*. A few minutes here and
> >>>> there
> >>>> is NOT enough; HOURS on the low bands are needed in order to catch the
> >>>> propagation peaks all across the NA and SA continents.
> >>>>
> >>> YES! Veteran expeditionerAA7JV recognized that topband openings
> >>> tendedto happen on one or two nights of a multi-week activation, and
> >>> developednetworks to allow simultaneous operation on CW and FT8
> >>> during every hourthere's a possibility of propagation. One of the
> >>> most glaring failuresis abandoning the band at the first hint of
> >>> daylight, when propagationPEAKS over the next 45 minutes to an hour!
> >>> 73, Jim K9YC
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