Using a 4m dish on 144 MHz makes only sense when using an offset dish to avoid blockage by the feed in my opinion.
I tested once my 7.3m offset dish on 2m feeding it with a 3 element quad, in average JT65 was 3...4dB better than on my 13 element yagi, receiving stations simultaneously. Simulation by NEC resulted in 19dBi gain.
As far as I remember many years ago Sergey, RW3BP wa using a 1.4m offset dish with success on 70cm.
Simulation can tell you more if you can expect an acceptable result with a prime focus dish. With luck even some gain enhancement might be possible with special distance between feed and reflector.
73
Hannes
---- Bob Atkins schrieb ----
> That dish would only be two wavelengths in diameter. I suspect gain
> equations probably don't do a great job at gain prediction
> under those conditions and the calculation of the radiation pattern
> would likely be inaccurate. I also doubt the pattern from a 2
> wavelength diameter dish is clean. I'd also assume almost any
> 144 MHz feed with a reflector will result in significant blockage or a
> 4m dish. There's this feed - http://www.ok1dfc.
> com/eme/technic/144feed/loop_feed_for_144_mhz.htm <http://www.ok1dfc.
> com/eme/technic/144feed/loop_feed_for_144_mhz.htm>. It's 1.26m in
> diameter and designed for f/d 0.4 though. I suspect the results
> will be disappointing. My 3m dish just about works on 432, but that'
> s a 4.25 wavelength dish, With a 2 wavelength dish (1.4m) I suspect I&#
> 39;d have problems! That being said, it would be an interesting
> experiment. You'd probably be able to hear/work something. You could
> probably work the biggest stations with a dipole! Good Luck, 73
> Bob, KA1GT From: Moon-net <moon-net-bounces(a)mailman.pe1itr.
> com> on behalf of Paul Andrews via Moon-net <moon-net@mailman.
> pe1itr.com>
> Sent: Monday, January 28, 2019 11:17 PM
> To: Moon-Net
> Subject: [Moon-Net] 144 MHz feed for a 4m dish Does anyone
> have a design for a 144 MHz feed that would fit on a 4m dish. My
> 2 x XP28 yagis produce nearly 20 dB gain. A 4m dish could produce
> 14 dB gain but with a much cleaner radiation pattern. This is an
> interesting experiment. Do I need a simple loop feed?
> Folded dipole and reflector? Some else? 73 - Paul - W2HRO
>
Does anyone have a design for a 144 MHz feed that would fit on a 4m dish.
My 2 x XP28 yagis produce nearly 20 dB gain. A 4m dish could produce 14 dB
gain but with a much cleaner radiation pattern. This is an interesting
experiment.
Do I need a simple loop feed? Folded dipole and reflector? Some else?
73 - Paul - W2HRO
All,
Seen many designs for 1Kw sspa on 144 Mhz with single LDMOS blf188/blf578 ( or the freescale devices with the long numbers ..)
Anybody seen a sspa for 432 Mhz with a single LDMOS fet that could deliver 1kw ??
Or is such a design on 432 Mhz just impossible due to the low impediance and too much heat .. ??
Should I concentrate on a 432 sspa single LDMOS device around 500 watt out
73's Rick ,PA1BVM
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Hi all
Has anyone successfully used the RTL dongle SDR Sharp combination to run
MAP65?
I am aware of the G4DCV article describing his using the RTL dongle with
HDSDR.
I already have Sharp SDR running well on a seperate pc and have installed
a VB cable.
My intention is to run MAP65 simply to monitor activity on the 2 meter
EME pass band.
Any thoughts or suggestions would be most appreciated.
Barry
ZL2LN
For Sale:
Brand new, never used, never outside PST2051EL Elevation Rotator. New
original bolts and nuts cable plugs.
I have mounted an external pot modification for a 3 turn 500 ohm pot, if
you want it. Otherwise I will remove it and you may use the original
positioning circuit, which is still intact.
Control box not included, rotator only.
$650 plus shipping from 40391
Dave, K4TO
>From 20 october - 29 october 2019 is A21EME in KG25wk QRV,
>From 20 october - 25 october 2019 6m, 2m, 70cm EME. Mode JT65 and CW.
>From 20 october - 29 october 2019 23, 13, 9, 6 and 3cm. Mode JT65 and CW
Group members:
Lins PA3CMC John ZS6JON Chris PA2CHR Paul ZS6NK Andrew ZS6AVH Bernie ZS4TX Sam HB9COG Dan HB9CRQ
Station:
6m 6M8GJ2m 2 x 12el X pole design I3DLI
70cm 2 x 28 el. m2
23, 13, 9, 6 and 3cm 1.5m dish 1x2mm mesh, automatic az and el control
1296: 100W at feed, circular, preamp at horn
23xx: 80W at feed, circular, preamp at horn
3400: 80W at feed, circular, preamp at horn
5760: 80W at feed, circular, preamp at horn
10xxx: 50W at feed, v-pol, preamp at hornAny donations are welcome.
Paypal <info(a)pa3cmc.nl>
Bank IBAN NL58INGB0006770934 BIC INGBNL2A
QSL direct or via buro
Direct wit SAE and €2 or $2, if not enough postage QSL send back via buro.
PSE NO IRC's NOT Accepted here. All sponsors automatically recieve QSL direct.
L Berben
Simonshoek 2
5768 CS Meijel
Netherlands
More will follow on my website www.pa3cmc.nl
73 Lins PA3CMC 2m EME DXCC #30
EA5/PA3CMC ZS/PA3CMC Z21CMC 3DA0LB
Member of Z21EME EME DX Expedition 2014Member of HV0A EME DX Expedition 2015
Member of 3DA0MB EME DX Expedition 2017Member of<http://www.pa3cmc.nl><http://www.mmmonvhf.de><http://www.mmmonvhf.de>
<http://www.pa3cmc.nl>
FS are (3) NOS, male-to-male (SMA), armored jumper cables. One is 60"
long and two are 240" long. They are made here in Pennsylvania by
UTI-Flex. These are lab quality & made with 26 GHz phase & amplitude
stable cable terminated with 18 GHz SMA SS connectors.
The model number for the 60" is UFA210B-1-600-300300 while the 240" are
UFA210B-1-2400-300300. From their online PDF the numbers mean:
UF – Light Aqua, FEP, A – Low Loss, 210 – Cable Diameter (inch x 1000),
but this is the inner coaxial cable. The outside Dia = 0.410" because it
is armored, B – 19 Strand Silver-Plated Copper wires for the center
conductor for maximum flexibility, Option 1 – Polyurethane Jacket Over
Braid & Stainless Steel Armored Spiral Guard, 600 & 2400 – Cable
assembly length (inches) i.e., (60.0") 5' or (240.0") 20', Connector
Option 300 – SMA male Plug, 18 GHz, Absolute max SWR of 1.16:1 to 18 GHz.
What is great about these cables is that they are very flexible yet up
to 450 pounds/in crush rated, double-shielded, armored, yet very soft,
flexible, & durable. Bend radius ~2" & can withstand 25,000 flexes of ±
90° around a four-inch (101.6 mm) diameter mandrel.
Asking $75 & FREE SHIPPING (in USA) for each of the 20' and $40 & FREE
SHIPPING (in USA) for the 5' jumper. Below are some pics of the two:
https://drive.google.com/open?id=1Wu_FybFtgZJthEgejmnu5Ebcm3FtAk_7https://drive.google.com/open?id=1n6rW-hnPCAhrbKteFPZIGcIpD_XvS7q0
Gedas, W8BYA
Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
One of the nice aspects of using linear actuators
(satellite dish arms) is the pulse train position
signal is monitored and disables 36v control
voltage if not present. These actuators have
huge torque thru helical screw jack which would
cause motor heating if stalled. Many come with
physical limit switches to stop over-travel. My
controller has end of movement electronic memory
which is programmed. Old stuff from 1980's but they were thinking.
Both my 2m and 6m arrays use Von Wiese actuators
(with 900 lb. thrust) and share same
control/PS. They are integrated into my RazTrak az-el control system, as well.
My dish uses actuators for both az and el
movement using Astron 28v PS and manual switching (so far).
GL with your efforts,
73, Ed - KL7UW
At 04:54 AM 1/25/2019, Paul Andrews via Moon-net wrote:
>My SPID RAS control box will stop sending DC
>power to the motors if movement (pulses) are not detected for 5 secondsÂ
>
>However, the program that drives the RAS control
>box does not get a message to stop trying to
>move the rotor. The tracking program continues
>to try and move the frozen rotor.
>
>This may have been why the Yaesu AZ/EL motor was
>damaged. Not one long burn but dozens of shorter burns.
>
>To Jan's point. a well written tracking
>program will report a rotor fault to the
>operator interface and terminate additional attempts to move the rotor.
>
>73 - Paul - W2HRO
>
>On Fri, Jan 25, 2019, 08:02 Jan Kappert via
>Moon-net
><<mailto:moon-net@mailman.pe1itr.com>moon-net(a)mailman.pe1itr.com wrote:
>To my honest opinion, it should not be to
>difficult to add some lines in the software,
>which checks actal movement after a command to move.
>Like check after 5 sec the command is given.
>When there is no movement, it will abort the command.
>Br. Jan
>_______________________________________________
>Moon-Net posting and subscription instructions
>are at
><http://www.nlsa.com/nets/moon-net-help.html>http://www.nlsa.com/nets/moon-net-help.html
>
>_______________________________________________
>Moon-Net posting and subscription instructions
>are at http://www.nlsa.com/nets/moon-net-help.html
73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
dubususa(a)gmail.com
Thank you all for your comments and opinions!
Some friends say "it is ok 13x13", according to W1GHZ and its mesh calculation sheet, this is a very poor gain (15db).
I'll see data from VK3UM, but I think mesh x2 is the only possible alternative.
I hope 2019 to be on the moon with you.
73, Ric Cx2SC
