[Moon] FW: [Moon-Net] Test

Mon Jun 26 14:53:45 CEST 2017

Hi Dominique

It is not a clear decision on whether LP or CP is "best".

The Prague decision was made I think before CP was tested rigorously on
10GHz.  The main issue seems to be depolarisation loss, which 10GHz
measurements indicate is worse on CP than LP. It seems that the
depolarisation effects get increasing more significant as frequency
increases, and are becoming noticeable certainly on 10GHz.  More info
here:

http://www.eme2016.org/wp-content/uploads/2016/08/EME-2016-G3WDG-Presentation.pdf

I now am able to rotate linear pol very quickly,  using a newly developed
feed (that is soon to be published in Dubus).  I took the opportunity
during the contest to see who was using CP and LP , and almost everybody I
worked was on LP.

The "upside" of LP v CP, as noted in my paper, is that the CP to LP loss
is only about 2dB, so you don't lose as much as you think.  The paper also
notes that for ultra small stations to big station, or small/medium
station to small/medium  station LP to LP gives better performance
(provided spatial offset is small of course).

So,  for stations deciding to go with CP, you won't lose too much when
working linear stations provided your CP is good (ie low axial ratio). I'm
not sure how good in this respect all feeds currently in use are.

On this basis, I think CP and LP happily co-exist and we don't need to
"insist" on one or the other.

BTW, re "excuses", I built a CP feed last year that works extremely well,
with low loss and an excellent axial ratio, but do not now use it on the
air.

73

Charlie

> Peter, Vlada
>
> the fact that using a 2.4m dish LIN Pol can truly random copy CP signal
> from 1m dish with only 50W at PA output (net at feed maybe 40W) is a very
> strong argument to change to CP for everybody, as decided at the Prague
> EME conference  long ago.
>
> Given, the LIN Pol stn would have had CP instead, the signal would have
> been much easier copied, all losses by the not perfect CP feed included.
> The advantage would have been approx. 2.5dB.
>
> I made 2 fully random QSOs CP with 1m dish and moderate power. Already
> 1.2m dish would improve another 3dB. Btw: I like "insane" power  by
> others, it enables me to copy them even with small dish and WP "wrong
> Pol")
>
> I think time has come to go CP. No more excuses.
>
> 73 Dominique
>
> HB9BBD
>
>
>
> From: vlada [mailto:vlada.masek at volny.cz]
> Sent: Montag, 26. Juni 2017 13:23
> To: Hansen Peter
> Cc: Moon-net; Dominique Faessler
> Subject: RE: [Moon-Net] [Moon] Test
>
>
>
> Hi Peter,
>
> very well, you touched everything, so I have nothing to add to.
>
> Looking for another "insane" beacon power from you on 6cm !
>
> GL and 73,
>
> Vlada for OK1KIR
>
>
>
>
>
> ______________________________________________________________
>> Od: Hansen Peter <peter.hansen at dk.saabgroup.com>
>> Komu: vlada <vlada.masek at volny.cz>, Dominique Faessler
>> <dfaessler at bluewin.ch>
>> Datum: 26.06.2017 12:56
>> PÅ™edmÄ›t: RE: [Moon-Net] [Moon] Test
>>
>
>> CC: <moon-net at mailman.pe1itr.com>
>
> Hi Vlada I found the conditions quite good I had roaring echo during the
> weekend.
>
>
>
> I have also given the CP/LIN some thoughts and I get by using V pol and
> twist in case of need. Problem is no one get their CP Feeds near the
> performance of Lin feeds. There are additional losses in the CP feeds.
> Furthermore when one design a feed it is almost not fitting 100%
> illumination wise. Specially in Offset dishes that can be felt. Also
> dimensions are quite critical on 3cm making a good Circular Feed.
>
> I would need a waveguide Feed for Andrew/channelmaster dish.
>
> I am sure it will be hard to get all to agree on the topic.
>
> Agreed power is insane at JLW and at my Station. Well my TWTA is a Class A
> TWT and does like making max power out in the feed. Otherwise it is just
> dissipated in the TWT. It draws 3000W from the 230V when PTT. It delives
> around 750W on the flange but big loss in feeder system.
>
>
>
> Why alligator power ???. Well it makes everybody able to hear a signal
> from the moon same as the Beacon but only better as there Is actually a
> person behind.
>
> I try to infect as many as possible to this challenging part of our hobby.
> Hearing a signal from the moon makes them want more.
>
> Even my own kids are very amazed when I let them say a few words and hear
> them back from the Moon :o).
>
>
>
> Vlada it is stations like you that makes the band a success as it is
> always possible to work you.
>
>
>
> By the way soon I be QROO on 5.7Ghz also I just got the Waveguide feeder
> so will make 500W where around 300W will hit my Feed horn that actually is
> CP :O)
>
> Have a nice day both of you.
>
> 73 Peter LPR
>
>
>
>
>
> From: moon-net-bounces at mailman.pe1itr.com
> [mailto:moon-net-bounces at mailman.pe1itr.com] On Behalf Of vlada
> Sent: 26. juni 2017 12:26
> To: Dominique Faessler
> Cc: Moon-net
> Subject: Re: [Moon-Net] [Moon] Test
>
>
>
> Hi Dominique,
>
> first sincere congrats to 1st CW 3cm QSO.
>
> However something still to think about as the both OZ1LPR and SP6JLW have
> huge TX power.
>
> Have you ever found ours 50W signal during the contest ?
>
> FYI, we made 32 CW QSOs.
>
> E.g. we made also random CW QSO with OK2AQ with 1.2m dish and similar
> power (close to 50W at max) at spread of 120Hz, but with linear
> polarisation !
>
> Seems, these 3dB is terrible difference in real ether !
>
> Probably, we shall live with LP vs CP troubles for some years and for many
> it is not as easy to swap it.
>
> Vy 73,
>
> Vlada&Tonda
>
> OK1KIR
>
> www.ok1kir.cz
>
>
>
>
>
> ______________________________________________________________
>> Od: dfaessler <dfaessler at bluewin.ch>
>> Komu: Rainer <df6na at df6na.de>, Moon Reflector <moon at moonbounce.info>
>> Datum: 26.06.2017 08:43
>> PÅ™edmÄ›t: Re: [Moon] Test
>>
>
>
>
> Hello All
> Yesterday I wkd my 1st. 3cm EME QSO withOZ1LPR. It took almost 45 minutes
> to complete due to my small signal. Later I had another chance with
> SP6JLW, - same proceedure taking 30 minutes.. Easy copy at HB9BBD.No
> chatroom arrangement or internet stuff, real EME in CW.Thank you guys for
> this great fun!
> Rig at HB9BBD: 1M offset dish, CIRCULAR  POL, 50W, home made LNA 0.65dB
> NF.
> 73 HB9BBD, Dominique
>
>
> Von meinem Samsung GerÃ¤t gesendet.
>
> -------- UrsprÃ¼ngliche Nachricht --------
> Von: Rainer <df6na at df6na.de>
> Datum: 26.06.17  08:04  (GMT+01:00)
> An: Moon Reflector <moon at moonbounce.info>
> Betreff: [Moon] Test
>
> pse ignore
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