| Offset dish vs. prime focus dish... ...dyskusja... |
| Ciekawa dyskusja...warto sie zapoznac... Dnia Wtorek, 22 Listopada 2016 20:57 <dl7yc@snafu.de> napisał(a) > Just another comment regarding the discussion offset dish vs. prime focus > dish: > > > Both "sides" claim better results, but reality shows the truth, hi. > > If you calculate the "shadow" of the feed-system (in my perspective > including the WG-switch, preamp, transverter AND TWT with power supply for > 10 GHz OR 24GHz) its 1-2% of the whole surface only !! (based on my 2.4 m > precision prime focus dish) > > The results for such a setup showing moon- and sunnoise results very close > as predicted in VK3UM`s programs. Compared with other well equiped stations > nothing is worse, therefore the effiency should be as high as caculated. > And...... the feed design and focal point adjustment / calculation is VERY > easy. > > Looking to my friends having offset dishes the same size, its all a bit > motre complicated. I know all the recommendations from Hannes well and they > where all very helpful. Even the "trick" with the waterhose, I think Dick, > PA2DW told this, is very nice and helps a lot.... > > But the offset feed design and adjustment to its phase center is much, much > more complicated than it looks. I personally know some very wellknown > Microwave EME friends, struggeling many times to "optimize" their dish > performance. > > If one loose 5% effiency due to a "bad" phase center, not perfect adapted > feed in respect to the dish`s f/D (i.e. wrong feed system selection) and > therefore spillover results in AZ or EL orientation due to "breaking" > the -10dB rule in one direction at least, this all together is MORE worse, > than a 2% "feedbox"-shadow of a prime focus RX/TX setup with no extra line > losses !! Its true ... , especially for the more rectangular beam of the > Super-VE4MA-Feed (Kumar feed / see W1GHZ handbook). > > Therefore, it could be allready an open question!! If one have a PERFECT > offeset dish setup, this might be 2% better compared to the same prime focus > dish setup ?? But if NOT, hmm.... > > My reccommendation: > > Try to put the equipment you need for the given band straight inline with > the prime focus feedhorn and beat your neighbour with more moonnoise > performance, hi. Forget struggeling and time consuming processes to optimize > overall performance of microwave EME dishes. > But, .... you really will loose the possibility to SIT on the ground for > adjustment of your offset feed, because NO adjustment is neccessary > anymore!! And the focalpoint of an 2.4m prime focus dish is 1.2 m far from > the surface only (plus some extra cm) Feed change is not a dangerous thing ! > > I NEVER re-adjusted the feedsystems in its focal point after a perfect > calculation and mechanical measurement by a laser distance meter from a > hardware shop. > > BUT at the end: its much more important to be QRV than to grab the last > tenth of a dB !!!!!!!!!!!!!!! > > Vy 73 Manfred, DL7YC > > > 2.4m precision prime focus dish (Areal OY Finnland), f/D 0.4 used for 10 GHz > and 24 GHz > VE4MA "Super feeds" for both QRG`s > 0.6dB NF (10GHz) 1.3dB NF (24 GHz) > DB6NT transverter with 10 MHz time base connection (GPS) > modified RW1127 TWTA`s with RWN 320 PSU`s > Output: > 90 watts (10GHz) 40 watts (24 GHz) > Autotracking NITEC rotator > > > -----Ursprüngliche Nachricht----- > From: moon-net-request@mailman.pe1itr.com > Sent: Tuesday, November 22, 2016 8:37 AM > To: moon-net@mailman.pe1itr.com > Subject: Moon-net Digest, Vol 289, Issue 16 > > Send Moon-net mailing list submissions to > moon-net@mailman.pe1itr.com > > To subscribe or unsubscribe via the World Wide Web, visit > http://mailman.pe1itr.com/mailman/listinfo/moon-net > or, via email, send a message with subject or body 'help' to > moon-net-request@mailman.pe1itr.com > > You can reach the person managing the list at > moon-net-owner@mailman.pe1itr.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Moon-net digest..." > > > Today's Topics: > > 1. Icom 9100 and RigBlaster Advantage (Richard Lawn) > 2. Re: FLEX 1500 & MAP65 (Edward R Cole) > 3. Re: 2.4M PRIME FOCUS / 2.4M OFFSET/ ALSO SEPTUM FOR 1296 > (Edward R Cole) > 4. Re: 3cx1500 or 3cpx1500 (Mark) > 5. Re: 2.4M PRIME FOCUS / 2.4M OFFSET/ ALSO SEPTUM FOR 1296 > (Hansen Peter) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 21 Nov 2016 18:24:12 -0500 > From: Richard Lawn <rjlawn@gmail.com> > Subject: [Moon-Net] Icom 9100 and RigBlaster Advantage > To: moon-net@mailman.pe1itr.com > Message-ID: > <CADQmrTGeLWopjcimwxCyaPX7fvKXcT5BchQc=_LnuQ-nZCjf_w@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > I took someone's advice and added the RigBlaster Advantage to my new EME > station. Now I'm getting sufficient audio in to WSJT and beginning to > decode some signals. Next step is activating PTT to the DEMI sequencer > which works great and PTT on the radio seems to work but I'm not getting > any audio in to the radio. I've fiddled and fiddled with the Icom menu but > to no avail. Someone out there must be using the 9100 with an external > sound card and I'd love to hear from you. > > 73 > Rick, W2JAZ > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mailman.pe1itr.com/pipermail/moon-net/attachments/20161121/12998028/attachment-0001.html > > ------------------------------ > > Message: 2 > Date: Mon, 21 Nov 2016 14:28:05 -0900 > From: Edward R Cole <kl7uw@acsalaska.net> > Subject: Re: [Moon-Net] FLEX 1500 & MAP65 > To: Cowles Andrus III K4EME <candrus@mgwnet.com>, Moon-net > <moon-net@mailman.pe1itr.com> > Message-ID: <201611212327.uALNRoje010308@mail42c28.carrierzone.com> > Content-Type: text/plain; charset="us-ascii" > > Cowles, > > I didn't reply on the Flex-1500 but have heard that quite a few who > bought them for eme or mw IF use with transverters had sold the Flex > citing freq instability and interfacing issues. > > I waited several years, using a FT-847 on 2m and on 1296 with144/1296 > transverter. But having heard such glowing comments on the K3 for > CW use, I decided using transverters with top-end HF radio made for a > superior eme and VHF-mw operation. I bought my K3 in 2010 and > commissioned DEMI to build a custom dual-Rx transverter to use with > MAP65 for adaptive-pol receiving (IQ+ was not available at that time). > > Since have acquired the 220, 432, 1296 transverters using 28-MHz as > std IF. I am not upgrading to the K3S as most of the upgraded boards > are available to install in my K3 (I bought the new synth boards > which I have not yet installed). I decided to buy the K3/10 which > does not have the 100w HF amp inside the radio. I also have a KX3 so > bought the separate KXPA-100 for use on HF/6m by either radio. Cost > is about the same. > > The K3S is expensive but ranks at the top of the list compared with > other HF radios and very popular with dxpeditions due to > size/weight. I think their transverter I/F is superb in comparison > with other makers. No computer I/F is required - > plug-n-play. Transverter output is 0.1-1.5mw so take that into > consideration for obtaining compatible transverters. Rx and Tx > separate connectors std. And great Tx-inhibit function makes > sequencing fool-proof. > > Guess you would say I like my K3. > > But saying that the KX3 is pretty nice and is usable with > transverters with a little more work in doing the I/F. > > 73, Ed - KL7UW > > At 09:35 AM 11/21/2016, Cowles Andrus III K4EME wrote: > > >I want to thank VE4MA, W2HRO, KC4SW and everyone else who responded > >to my email about using the FLEX 1500 with MAP 65. > > > >It appears at this time no one has been able to get theses two to > >play together, so I don't plan to buy the FLEX 1500. > > > >Some have recommended the Elecraft K3S! > > > >The K3S would cost considerable more than the FLEX 1500, so I may > >put the K3S on my wish list! > > > >Thank you & 73! > > > >Cowles K4EME > >Home page: <http://cowlesradio.webs.com/>http://cowlesradio.webs.com/ > >_______________________________________________ > >Moon-Net posting and subscription instructions are at > >http://www.nlsa.com/nets/moon-net-help.html > > 73, Ed - KL7UW > http://www.kl7uw.com > "Kits made by KL7UW" > Dubus Mag Business e-mail: > dubususa@gmail.com > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mailman.pe1itr.com/pipermail/moon-net/attachments/20161121/d5b0fc96/attachment-0001.html > > ------------------------------ > > Message: 3 > Date: Mon, 21 Nov 2016 14:54:38 -0900 > From: Edward R Cole <kl7uw@acsalaska.net> > Subject: Re: [Moon-Net] 2.4M PRIME FOCUS / 2.4M OFFSET/ ALSO SEPTUM > FOR 1296 > To: serge <ve1kg@eastlink.ca>, moon-net@mailman.pe1itr.com > Message-ID: <201611212356.uALNuGoa023083@mail40c28.carrierzone.com> > Content-Type: text/plain; charset="us-ascii" > > Serge, > > Just my opinion but if you can acquire an offset feed dish I suggest > its slightly better: > 1. Feed does not block part of the dish surface (no apparent shadow) > 2. It requires a narrower beamwidth feed that may improve rejection > of ground noise pickup (lower sidelobes; better G/T) > 3. You can mount all the electronics at the feed eliminating > feedline losses (max bang for the buck) > 4. Often these dish surface are rated to 10-12 GHz so multi-band use > is greater. > > The feed support would need to be robust to handle the higher weight > at the feed. > Dish may be fiberglass vs mesh so heavier weight. > Cost may be higher > > Az-El requirements are the same. > > Offset dish needs a feed designed for a F/d of 0.6-0.7 (W2IMU would > work). Ordinary septum would not be good. > I believe VE4MA is using one on 24/47 GHz so ask him about feedhorns. > > I have a idle 1.8m offset feed dish I am considering for 10-GHz > use. It used to be our satellite-TV dish until recently switching to > Direct-TV (which included free dish and HD receiver). Recently > occurred to me that 6-foot (1.8m) makes it a candidate for portable > use with our RV trailer. > http://www.kl7uw.com/1.8m_dish.jpg > > 73, Ed - KL7UW > > At 12:00 PM 11/21/2016, serge wrote: > >Which is best a 2.4M prime focus dish or a 2.4M offset dish? & WHY? > >What kind of septum would you use on both dishes for 1296??? > >Thank you > >Serge, VE1KG > >_______________________________________________ > >Moon-Net posting and subscription instructions are at > >http://www.nlsa.com/nets/moon-net-help.html > > 73, Ed - KL7UW > http://www.kl7uw.com > "Kits made by KL7UW" > Dubus Mag Business e-mail: > dubususa@gmail.com > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mailman.pe1itr.com/pipermail/moon-net/attachments/20161121/22463f92/attachment-0001.html > > ------------------------------ > > Message: 4 > Date: Tue, 22 Nov 2016 00:23:04 +0000 > From: Mark <EA8FF@yahoo.com> > Subject: Re: [Moon-Net] 3cx1500 or 3cpx1500 > To: moon-net@mailman.pe1itr.com > Message-ID: <3e5c9c39-211b-84e7-d078-7d83d4999470@yahoo.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > Hi, > > 3cx1500 and 3cpx1500 are the same tubes, they were probably selected > after production on flashover voltage and stamped differently. the > 3cpx1500 were more expensive than the 3cx1500. Nowadays new design uses > LDMOS and most people think the 3cpx1500 is only for pulse, thats why > there less expensive. Same thing with 3cx800 and 3cpx800. > > 73, Mark EA8FF > > > > ------------------------------ > > Message: 5 > Date: Tue, 22 Nov 2016 07:36:40 +0000 > From: Hansen Peter <peter.hansen@dk.saabgroup.com> > Subject: Re: [Moon-Net] 2.4M PRIME FOCUS / 2.4M OFFSET/ ALSO SEPTUM > FOR 1296 > To: Edward R Cole <kl7uw@acsalaska.net>, serge <ve1kg@eastlink.ca>, > "moon-net@mailman.pe1itr.com" <moon-net@mailman.pe1itr.com> > Message-ID: > <8d659953b4264132b3a5212f53301d4f@corpappl841.corp.saab.se> > Content-Type: text/plain; charset="iso-8859-1" > > Hi All I am an extensive user of a Offset dishes. > I started out with a 1.8meter offset dish (6foot) with 35W in the feed. I > worked easily 35initials on CW and it would have been going on. But 1? year > ago I changed to a 2.4meter Offset dish and this really opened the world. I > use the dish on 3 and 6cm currently but will do 24Ghz also. My dish is > channel master/Andrew dish. The mesh is small enough for use on 24Ghz. > I can confirm most of the things KL7UW states. The dish is easy to feed > linear on 3cm as there are waveguide feeds used originally that works great. > On 6cm where I am circular I designed my own feed type as I find W2IMU feed > little off peak being used for my dish. I had 0.2dB too little Moonnoise on > 6cm. I know I could have tried with larger W2IMU feeds but I went another > way. > Efficiency is much better on the Offset dish due to low blockage and higher > efficiency in the Feed to illuminate a higher F/d. > > What can be worked on a 2.4meter ?? > 3CM > I worked a 90cm that was using 12W in JT4F EME > I worked a 90cm that was using 25W in CW > > 6CM > I worked a 1meter and 10W in CW > > Many qso is possible just try it out. > > All forgot one VERY NICE feature on Offset dish. When I work on my Feeds, > Change system etc I simply sit on the ground and have the feed just in front > of me. Or I can tilt the dish and work on it standing up. > > > 73 Peter OZ1LPR > > From: moon-net-bounces@mailman.pe1itr.com > [mailto:moon-net-bounces@mailman.pe1itr.com] On Behalf Of Edward R Cole > Sent: 22. november 2016 00:55 > To: serge; moon-net@mailman.pe1itr.com > Subject: Re: [Moon-Net] 2.4M PRIME FOCUS / 2.4M OFFSET/ ALSO SEPTUM FOR 1296 > > Serge, > > Just my opinion but if you can acquire an offset feed dish I suggest its > slightly better: > 1. Feed does not block part of the dish surface (no apparent shadow) > 2. It requires a narrower beamwidth feed that may improve rejection of > ground noise pickup (lower sidelobes; better G/T) > 3. You can mount all the electronics at the feed eliminating feedline > losses (max bang for the buck) > 4. Often these dish surface are rated to 10-12 GHz so multi-band use is > greater. > > The feed support would need to be robust to handle the higher weight at the > feed. > Dish may be fiberglass vs mesh so heavier weight. > Cost may be higher > > Az-El requirements are the same. > > Offset dish needs a feed designed for a F/d of 0.6-0.7 (W2IMU would work). > Ordinary septum would not be good. > I believe VE4MA is using one on 24/47 GHz so ask him about feedhorns. > > I have a idle 1.8m offset feed dish I am considering for 10-GHz use. It > used to be our satellite-TV dish until recently switching to Direct-TV > (which included free dish and HD receiver). Recently occurred to me that > 6-foot (1.8m) makes it a candidate for portable use with our RV trailer. > http://www.kl7uw.com/1.8m_dish.jpg > > 73, Ed - KL7UW > > At 12:00 PM 11/21/2016, serge wrote: > > Which is best a 2.4M prime focus dish or a 2.4M offset dish? & WHY? What > kind of septum would you use on both dishes for 1296??? > Thank you > Serge, VE1KG > _______________________________________________ > Moon-Net posting and subscription instructions are at > http://www.nlsa.com/nets/moon-net-help.html > > 73, Ed - KL7UW > http://www.kl7uw.com > <http://www.kl7uw.com/> "Kits made by KL7UW" > Dubus Mag Business e-mail: > dubususa@gmail.com<mailto:dubususa@gmail.com> > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mailman.pe1itr.com/pipermail/moon-net/attachments/20161122/e8850b4a/attachment.html > > ------------------------------ > > _______________________________________________ > Moon-Net posting and subscription instructions are at > http://www.nlsa.com/nets/moon-net-help.html > > End of Moon-net Digest, Vol 289, Issue 16 > ***************************************** > > _______________________________________________ > Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html |