Tuesday, 24 July 2018

3D printing UHF filters


3D printing UHF filters






https://all3dp.com/1/creality-ender-3-3d-printer-review/







Settings
https://www.youtube.com/watch?v=umulfK775i0


https://ultimaker.com/en/products/ultimaker-cura-software


https://ultimaker.com/en/resources/50296-which-material-should-i-use


Copper and silver plating
https://bryancera.blogspot.com/2014/09/copper-electroplatingforming-3d-prints.html
https://www.riogrande.com/category/tools-and-equipment/plating
https://janekits.com.au/products/copper-mix-inc-cumac-4-ltrs/
http://www.vitec.com.au/shop-online/pat-coleby-minerals/copper-sulphate

https://www.finishing.com/111/72.shtml
https://www.eevblog.com/forum/manufacture/my-way-to-professional-prototype-at-home/25/
https://www.thinktink.com/stack/volumes/voliii/consumbl/cplatmix.htm
https://www.thinktink.com/faqs/cupltfaq/cupltf01.htm












HP AGILENT 8935 E6380A RF TEST SET


HP AGILENT 8935 E6380A RF TEST SET

Service Monitor for HF and 2 way radio. They all generate AM, FM and have a calibrated output signal generator, have 2 separate audio tone generators, have 2uV sensitive "off the air receivers" with antenna input, encode/decode standard tone (PL) (CTCSS), have sinad, distortion, S/N meters, receive AM, FM and SSB, have modulation / deviation meter, frequency error meters.





Overview and screens for HP 8935 E6380A
http://www.amtronix.com/e6380a.htm


Comparison with other HP test sets
http://www.amtronix.com/diff.htm



All manuals available through Keysight, just search E6380.

Sunday, 15 July 2018

Commercial low power UHF DVB-T pass-band/notch filter

Commercial  DVB-T pass-band/notch filters: What we can learn

Introduction

Low power, UHF and VHF DVB-T pass-band/notch filters are commercially available at relatively low cost, ~US$750 that seem suitable for DATV. They seem a good off the shelf solution.

By examining such filters, it seems possible to see how they might work, giving some insight into possible home-brew.

The filters have two notch filters, one for each side of the signal, as per my earlier posts, to notch the TX skirts.

In addition, they have cavity pass-band filters to take out artefacts further out. A manufacturer indicates that the pass filter is a combline, but the mechanical construction suggests cavity filters with openings between cavities for coupling.

It seems possible to separate the notch and band-pass filters. For wideband UHF, two notch cavities and a pass-band filter. For 2m, two notch cavities and a single pass cavity may suffice.

Low-pass filters are still needed for odd harmonics in addition to a DVB-T filter.

Commercial filters DVB-T (UHF and VHF)

The UHF first commercial filter seems to have five band-pass cavities and two notch cavities, one at either end. The input, notch and first pass resonator seem to share the same cavity, similarly for output. Three of the resonators are in individual cavities. On the top, RHS of the filter are the resonator tuning knobs.

 http://www.com-tech.it/products/cl-series-c/




From the response curves, the two sharp notches are evident to filter the skirts. This is similar to what I found in earlier posts on notch duplexers for DVB-T. However, one pair seems sufficient, something I have been working on, rather than 3 pairs in a duplexer.

How the notches work is not particularly evident. The connector has a loop coupling per the manufacturer's claim of DC to earth for lightning protection. There is a protrusion on the opposite side of the connector, the purpose of which is not evident. The notch and first pass-band resonator seem to be in the same cavity. Each resonator may be energised, one as a notch, the other as the first resonator of the pass-band filter.

The response shows the five minimums in SWR from the five cavities. The pass-band is shown without ripples, which seems a bit optimistic.

The response also shows the filter losses, less than 1 dB according to the specifications; quite remarkable!



The filter is meant to be a combline, presumably similar to the diagram from Piette 2010.


However, the cavities seem to have openings between them as the line of screws do not go all the way. It would seem to be similar to the band-pass filter from Piette 2010. It is not clear from the first drawing if there are screws to adjust coupling, but there seems to be another adjustment next to the resonator tuning.

From the mechanical design, it does not seem to be an inter-digital filter.


The filter is quite small,

Third harmonic?

Size Power


http://www.com-tech.it/products/cl-series-c/
http://www.com-tech.it/glossary/xline/
http://www.sira.mi.it/en/products/broadcasting/8/uhf-dtv-filters/287

http://www.microwavefilter.com/FCC_Repack.html
http://www.sira.mi.it  http://nintermedia.com/pdfs/tv/CTV-V-DVB-025.pdf

Homebrew DVB-T TX filter?



http://www.ocicom.com/index.php/amateur-radio/products/440-mhz-bandpass-filter
Bernard Piette 2010 VHF/UHF Filters and Multicouplers: Applications of Air Resonators










Wednesday, 11 July 2018

450 MHz CDMA duplexer tear down and analysis


450 MHz CDMA duplexer tear down and analysis- draft

Introduction


Why?

I am interested in how modern duplexers work. The club purchased a new 70cm duplexer, only 50 mm tall and not obvious how it worked, but they didn't want me opening it for a look!

I purchased a CDMA duplexer from Russia on the 450 MHz band on eBay. It was similar to the 70 cm one. I could get some idea how the UHF one works and some(?!) chance of re-tuning it for either a 70 cm DVB-T TV filter, 7 MHz bandpass, or as a 70 cm narrow pass band repeater duplexer (or both, as there are three chains of seven cavities in the device.

Unfortunately, I did not take photos of the duplexer's response before I opened it. However, it was a 6 MHz pass band, with steep skirts, and low pass in the 450 MHz band. I will do it when I put the top back on, but have probably disturbed the tuning. CDMA signals are 1.23 MHz wide, so it is unclear why the pass band is 6 MHz.

The outside, with a zillion screws out. The left three connectors are all SMA, the right are 7/16 DIN and N adaptors that I added.

The gizzards!

Click photo to see captions larger!!


It is a complex beast, requiring a very detailed examination to see all its features. Pore over the photo to see.

?? = I think!

The duplexer has three chains of cavity filters, RX (top), RX monitor (middle) and TX (bottom). RX has its own antenna. TX and RX monitor share an antenna, but are on different frequencies. Tx input is to left. The resonators use big capacitive hats to electrically shorten the resonator to one rack height, otherwise four rack high. The resonator adjustment screws are the larger screws.

The filters are pass band and low pass. The low pass comes from the capacitive tuning into the resonator??

The filter chains are pass-band, iris-coupled (port-tuned) filters that have a sharp cut off. The iris-coupling screws are the smaller screws. In addition to iris-coupling, both inductive (on lid) and capacitive inter-cavity coupling are used. I don't know why, presumably to get a sharper response (or impedence matching??). There are no notch filters, as are used in DVB-T filters, to get a very sharp cut at the edges of the pass band.

The input/output are either a separate smaller resonator with a gamma match?? coupling (left), or a conventional gamma match?? coupling direct to the main resonator (right).










Sunday, 8 July 2018

Rohde & Schwarz CMU200 Universal Radio Communication Tester resources

Rohde & Schwarz CMU200 Universal Radio Communication Tester resources

Introduction

This post is a collection of information for the Rohde & Schwarz CMU200 Universal Radio Communication Tester that I have purchased. They can be bought on eBay and other places often for a very reasonable sum. In its day it was an expensive but capable instrument.

While the CMU200 is primarily designed for testing now obsolete mobile phone equipment, it can be used for working with analog radio. It has a spectrum analyser, RF generator, RF power measurement and with the option, an audio test set. While not directly having a tracking generator function, there are two PC programs that allow it to be used for testing filters. It can also be done with a noise source or an external tracking generator.

The CMU200 uses an embedded Celeron or similar AMD processor running MS-DOS. It has an internal IDE HDD that is wise to replace as the instrument can do tens of thousands of hours. An IDE SSD allows the instrument to boot much faster.

Documentation is available from R&S. The CMU200 is discussed often in the eevblog forum.

The CMU200 can be used with a PC via a GPIB USB adaptor. There is R&S and third party software that increases the instument's functionality.

I have compared a duplexer response with the CMU200 and Siglent SSA3021Z with a $20 noise source and the Siglent's tracking generator.

My machine while replacing HDD, yes that is it on the top. The screen is dimmed around the edge presumably from curling of reflector around fluro tube. Will fix/replace. Screen is spectrum analyser showing local DVB-T TV stations. Nice!

Resources

Search "CMU200" in:
https://www.rohde-schwarz.com/us/home_48230.html
https://gloris.rohde-schwarz.com/anonymous/en/pages/toplevel/home.html?    must register (free)
https://www.eevblog.com/forum/index.php
https://www.mikrocontroller.net

Replace HDD with SSD

My analyser had its original HDD c2000 with 35000 hours. As such I was keen to back it up and replace it. No trouble extracting HDD or backing it up. I unsuccessfully tried the Kingspec drive as per below, but the drive was not recognized. I did the same with an old 20GB HDD from a laptop and that worked fine. My analyser uses earlier AMD CPU and older BIOS. That may be the difference? Cute using PS2 keyboard on an instrument to do MSDOS.

cut and paste from eevblog forum in italics

"The HDD-Raw-Copy-Tool tool does a sector by sector copy of the entire drive. The resulting RAW image can be opened by a tool like PowerISO and this what I used to upgraded the CMU200 DOS software.

Both the CMU200 Celeron and CRTU-RU Pentium III boards have worked with various Fujitsu 20GB and IBM 30GB IDE drives I have connected.  BIOS has autodetected all OK. I have replaced the CMU200 drive with Kingspec PATA IDE 2.5" 32GB SSD and again HDD-Raw-Copy-Tool was used to write the image to the drive before installation. Now the CMU200 boots like a rocket.

I note the Award BIOS FLASH tool and bios image can be found in \internal\install\bios folder. Run the batch file FLASH.BAT to reflash."



"1) remove the hard drive from the CMU, and attached is to a device like this: http://www.dx.com/p/unitek-y-3321-usb3-0-to-ide-sata-hard-disk-drive-hdd-docking-converter-black-230128

2) made an exact image of the drive to a file with this software: http://hddguru.com/software/HDD-Raw-Copy-Tool/ (I used the portable version to avoid installing the software)

3) removed an IDE harddrive from a back-up USB drive I had lying around (the HD in my CMU was a 20GB one, but I replaced it with a 40GB one without any issues

4) restored the image from the file to the "new" HD using the same software as in step 2"

Screen fix: LCD & EFI glass

LCD fix or replace

The screens can fail or go dim. A dim screen seems to often be just the reflector curling around the tube. The tube back-light can be replaced with LED strip.
Detailed fix:  http://www.rbarrios.com/projects/LCD2LED/
https://www.eevblog.com/forum/repair/rohde-schwarz-cmu200-lcd-backlight-success/

It seems possible to replace the screen with a new one. The screen seems to be a Sharp LQ084V1DG21  They are on eBay for US$100+. I have ordered one and will replace it when it arrives, with a report here. Main trouble with mine was EFI glass.

PDF: https://www.mouser.com/ds/2/365/LQ084V1DG21_SP_071305-184349.pdf
Graphic LCD Display Module Transmissive Red, Green, Blue (RGB) TFT - Color Parallel, 18-Bit (RGB) 8.4" (213.36mm) 640 x 480 (VGA)

EFI glass

The EFI glass commonly discolours. It was the main problem with my CMU200. Removing the glass fixed the problem, but getting a replacement EFI glass is a problem, but looking. The screen is still a little dim and I will replace it.

Manuals

Operating, quick start and service manuals:
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/sr001Man?OpenDocument

manufacturer page:

https://www.rohde-schwarz.com/en/product/cmu200-productstartpage_63493-7830.html

and the brochure:
https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/CMU200_bro_en.pdf

Detailed specifications:
http://www.upc.edu/sct/documents_equipament/d_175_id-448.pdf

Service manual:
https://www.ntecusa.com/docs/RS_CMU200_CMU300_other.pdf

Drivers
https://www.rohde-schwarz.com/us/driver/cmu200/

Firmware

Only the most recent firmware seems to be available from R&S. Earlier versions seem to have expired. Probably a good idea to keep a copy of current firmware before updating. May be a good idea not to update if little extra functionalityis added. See firmware text file for earlier versions.

CMU200 last firmware downloadable via R&S GLORIS account (picture is screen shot from GLORIS not links). Other links are below.

Base 5.21 firmware
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/SR001Z?OpenDocument
CMU200_GSM_5.22
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/SR003Z?OpenDocument
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/SR004Z?OpenDocument
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/SR006Z?OpenDocument
CDMA 2000 MS 5.20 package is here :
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/sr009z2?OpenDocument
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/sr015m?OpenDocument - manual
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/sr015Z?OpenDocument - install

http://www3.rohde-schwarz.com/www/FileTranCS.nsf/alias/DATS?OpenDocument - It is PC part of CMU-K92 option, GPRS application testing package. Manual is also there.




All new firmware?
http://gotroot.ca/cmu200/

Text file from eevblog?
https://www.mikrocontroller.net/attachment/337287/EEVBLOG_CMU200.txt

R&S software

CMU200 Software- CMUgo- Remote control software
https://www.rohde-schwarz.com/au/software/cmu200/

RSCommander
https://www.rohde-schwarz.com/de/applikationen/rscommander-flexibles-software-tool-fuer-instrumente-von-rohde-schwarz-application-note_56280-15410.html

The free software FreRes from Rohde & Schwarz allows to make sweep and test for example filters or duplexers.
https://www.rohde-schwarz.com/us/applications/freres-program-for-frequency-response-measurements-application-note_56280-15551.html
https://www.keysight.com/upload/cmc_upload/All/readme_IOLibraries_18_1_22603_1.htm?&cc=US&lc=eng

Third Party software

http://vma-satellite.blogspot.pt/2018/03/vma-simple-spectrum-analyser-for-crtu.html
https://vma-satellite.blogspot.com/2018/06/remote-control-of-r-cmu200-and-crtu.html
https://vma-satellite.blogspot.com/2018/03/vma-simple-spectrum-analyser-for-crtu_24.html

My unit

Serial Number: 10133X, X=bd-23
Options
CMU-B11 (HW): Reference oscillator OXCO, aging 2 X 10E-7/year
CMU-B12 (HW): Reference oscillator OXCO, aging 3.5x10E-8/year
CMU-B21 (HW): Universal signalling unit CMU-B21V14 incl. CMU-B54
CMU-B41 (HW): Audio Generator and Analyzer
CMU-B83 (HW): CDMA2000® signaling unit (requires R&S®CMU-U65)
CMU-U61 (HW): PCMCIA
CMU-U65 (HW): Upgrade kit for CMU200: Measurement DSP module for measurement speed improvement
CMU-K29 (SW): Analog AMPS, for CMU-B21, CMU-B41 required V5.20
CMU-K84 (SW): CDMA2000 (cellular band) for CMU-B83 V5.20
CMU-K85 (SW): CDMA2000 (PCS band) for CMU-B83r V5.20
Hardware
Front Module: FMR5
CPU: AMD K6-III
Memory: 128 MB
Firmware: V8.50 02.05.06

Duplexer tuning

A duplexer response with the CMU200 and Siglent SSA3021Z with a $20 noise source and the Siglent's tracking generator, respectively. The tracking generator is best, not surprisingly, but the noise source with the CMU200 is quite usable. Adjusting for insertion loss would be awkward. A noise source avoids needing a PC to run the tracking generator in the CMU200.





VMA simple spectrum analyser/remote-control-of-r-cmu200

I tried out VMA's spectrum analyser software with a Agilent 82357B USB GPIB adapter and the . Needed to read the instructions, but easy enough to get going. Works nicely, giving a waterfall to the CMU200 spectrum.

The Keysight IO control package screen


VMA's spectrum analyser screen shot showing waterfall and eight local DVB-T free to air channels. Nice!


The CMU200 screen set as per the last VMA photo above (with EFI glass removed, no brown edge, but still a bit dim)




Friday, 18 May 2018

The Black Art of Duplexers: Demystifying Cavity Filters



The Black Art of Duplexers: Demystifying Cavity Filters

I prepared a presentation for the Wireless Institute of Australia (WIA) annual general meeting practical day on cavity filters and duplexers. Others may find it useful. Links to the files at at the end.

I have had some comments on the paper. I will include them here and amend the presentation.

Abstract

A practical guide to the black art of cavity filters for repeaters and digital TV transmitters. Cavity filters are a mystery to most, but at a practical level, not that hard to make or tune. Drew has developed an inexpensive way of building filters using common materials.There are three basic types of filter, pass-band, pass-reject and notch. It is down to the coupling design, which again can be modified or home built. Each has particular applications. All three can be used in repeater duplexers at VHF and UHF. Notch can be used to block unwanted signals like paging TX. Drew will demonstrate a unique use for notch cavities for cleaning the spurious skirts of DVB-T television power amplifiers and the use of low cost software defined radios (SDR) as test instruments for general use and cavity/duplexer tuning. Finally, low cost software defined radios (SDR) and noise sources as spectrum analysers and "tracking generators" for general use and tuning cavities or duplexers is noted.

Overview

Cavity filters

  • How they work
  • Different types
Duplexers

  • How they work
  • Cables
  • Tuning
  • Homebrew
Improvised instrumentation

Tuning repeater front-ends

Other uses of cavity filters
  • Filter for DVB-T TX artefacts
  • Notch nuisance signals: pagers
  • High Q filter for very weak signals

Further information


PDF of Power Point presentation:
https://www.dropbox.com/s/s6tgcddf53yz68t/The%20Black%20Art%20of%20Duplexers.pdf?dl=0

Power Point if someone wants to use it:
https://www.dropbox.com/s/nfos04j7ujqkk5p/The%20Black%20Art%20of%20Duplexers.ppt?dl=0

Some of the few books on the subject:

Piette Bernard, VHF/UHF "Filters and Multicouplers, Applications of Air Resonators", Publisher: John Wiley & Sons, USA & ISTE UK 2010

Zverev Anatolij, "Handbook of Filter Synthesis", Publisher: John Wiley Sons 1967

Some extra web pages:

http://www.repeater-builder.com/antenna/andrew/andrew-about-rf-communications.pdf

https://www.lewczuk.pl/krotkofalarstwo-1/strojenie-duplekserow/104-przestrajanie-filtrow-dupleksowych Google Translate. Very good on tuning mobile duplexers.

https://www.lewczuk.pl/krotkofalarstwo-1/projekty/110-duplekser-2m

Saturday, 5 May 2018

Earth Moon Earth communications

Earth Moon Earth communications- very draft

Introduction

Josh, a new call, VK4JNA, suggested doing EME. I quickly went from uncertain to keen as it is very similar to satellite tracking, a long term interest. This post is on EME thoughts, mainly as a record of what we have found; I have a bad memory. It will be updated as we proceed. There will be spin-off posts on things of particular interest.




Antenna systems

Mast and rotators

Locate the antenna at the club; keep partner and neighbours happy.

The club has a new tilt-mast for UHF/VHF. Needs to be erected, about $600 to drill hole and concrete. https://www.nbsantennas.com.au/ A priority to get foundation and mount done as the concrete takes a month to cure.

The club has a new G-5500 Yaesu EL/AZ rotator. It needs the AL and EZ rotators to be mounted separately to suit the carriage of the mast.

The club has a computer rotator controller. https://ea4tx.com/en/tienda/antenna-rotator-system/ars/

I also have the same mast, two of the EL/AZ rotators and a EA4TX controller. The mast base is in, but I need to erect the mast. I have the controller working with the rotators. I was building them for satellite tracking.

While EME and satellite tracking can be done at ground level, having them on a mast gets them above trees, buildings and other obstacles for a 360 degree view of the sky. A view to the horizon is quite important in EME as that is when most QSOs are done.

Antenna

The antenna depends on the bands used. For 70 cm, a Yagi array is the norm. At 23 cm a dish can be used. Could use dish on 70cm as there designs for antenna and feedhorns.

Yagi array

When I first got back in radio, I researched building high-performance 2m and 70cm Yagi for satellite tracking. I have all of the components to build both, I was following the design in the ARRL handbook that uses insulated elements for low noise. The antenna uses 25mm square section boom, nylon top hat washers and push-nuts to secure the elements.

For satellite tracking, the Yagi can have have both vertical and horizontal polarisation on the same boom, with phasing to get circular polarisation. The small satellites tumble, so both polarisations are necessary.

I had two 2400mm fibreglass poles made locally at $80 each. They were to mount two dual polarisation Yagi for 2m and 70cm. The satellites are repeaters with different band for up and down. The poles simplify mounting as they are insulators and do not interfere with the antenna, allowing centre of gravity mounting. Such mounting reduces the load on the EL rotator.

For EME, the same poles could be used to create the H to mount four Yagi. The EME Yagi are usually single polarisation and easier to make, even though the returning signal has mixed polarisation. I may need to get some more antenna components, but they are not expensive, less than $100. Priority to make first Yagi.

http://www.qsl.net/dk7zb/70cm-longyagi/13-ele.htm Not sure why they don't have better reflectors to stop noise, but front to back ratio is 30 db. Apparently ground effect, but this seems odd if QSOs are near horizontal. Important for echo testing, with the moon viable during the day. Probably a first objective.

http://www.g0ksc.co.uk/18el-432mhz-lfa-yagi.html
https://www.innovantennas.com/index.php/en/ shop
http://www.stauff.com.au/index.php?id=3911&L=1&MP=3897-5448 30mm above boom clamps
http://miningandhydraulics.com.au/contact-us clamps 1/4" $1.20 each + GST

http://www.company7.com/telrad/products/telrad.html Telrad- telescope aiming device



I have a 2m Yagi with insulated elements and a double T match. It is mechanically easy to make.  http://www.pa0ply.nl/articles/Matching%20of%20432Mhz%20Yagi.pdf

Comments from Moon-Net email: re 12.5 Ohm Yagi
YU7EF
DG7YBN


http://www.vhfdx.ru/apparatura/8x18elements_430mhz 50 Ohm insulated
200...300 OHm-technology (50...75 x 4= approx 200...300).
This is one of the correct solutions for 432 at the small stack:
http://www.ifwtech.co.uk/g3sek/eme/pol2.htm
This is the BG's solution:
http://www.ifwtech.co.uk/g3sek/eme/pol2.htm
http://www.df6na.de/dl9kr.htm
Note that Jan, DL9KR works only by CW.
World record of Jan: more 1000 initials in CW mode only.

Also, DL7APV's solution with the open feed line technology:
http://dl7apv.darc.de/

Yagi stacking

Stacking and power divider design in coax or aluminium square section.

Coax/Heliax- less connectors

Square coaxial- ratio of outer and inner diameters. copper, brass or aluminium rod.
https://www.dxmaps.com/VE7BQH70.html- comparing 70cm Yagi
http://www.qsl.net/dk7zb/Stacking/stacking.htm coax and aluminium
http://www.innovantennas.com/our-antennas/view/productdetails/virtuemart_product_id/136/virtuemart_category_id/13.html
http://home.teleport.com/~oldaker/power_dividers.htm QST article

Parabolic Dish antenna

I used to play with satellite TV as I am into home theatre. Prime focus C band 2300mm dishes are cheap new, about $250, but are also available for about $100 used on Gumtree. New is probably easier as collecting used ones are a hassle.

http://www.satking.com.au/satellite-tv/satellite%20tv-%20cband%20dishes/satking-2-3m-standard-c-band-dish

The dishes use a polar mount and can track the geo-stationary TV satellites by rotating in one plane using a linear actuator. The actuators have a reed switch so a controller can follow the tracking.

For EME on 23cm, the dishes need full EL/AZ control. That might be possible with linear actuators and a small computer control, but I am not aware of one (but haven't looked either). It might be possible to use the EA4TX controller, although it uses a variable voltage for position; all rotators use this.

It may be possible to use a Yeasu EL/AZ rotator with the EA4TX controller. The dish would need to be mounted at ground level to reduce wind loads, but the weight of the dish itself is not high. That would simplify mounting and control.

There are designs for the 23cm feed horn and antenna around. They can be made from sheet copper, which I have. The feed horn is to reduce terrestrial noise.

Probably easier to do Yagi array first then try dish. Put dish mount pole in when mast foundation done- Priority

http://2ingandlin.se/Feed_comp_432_MHz.html
http://www.ok1dfc.com/EME/technic/432feed/432feed.htm

Cables

We have 1/4" Heliax, possibly other sizes may be available at the club. -2.7db/30m (1/2" -1.6db/30m). For phasing lines. http://www.rfiwireless.com.au/media/downloads/pdfs/andrew-corrugated.pdf

For main cable either coax or open line. Coax easier and after preamp(s) and cavity filter. Will check on open line (shielding?)

Coax cable is the greatest loss in the RX/TC system. 50 Ohm RG142 is commonly used. So is RG814. The club has two 100m roles of RG214. It is thick and suited to long runs. We may need to get some more RG142, although I have some. The main advantage of these cables is the shielding to keep extraneous noise out; their losses are similar to common RG213.

Another cheap alternative is 75 Ohm satellite TV coax. It is quad shielded and low loss as it is designed for the first IF of satellite RX from 1 to 2 GHz. It could be used for TX up to 100W pulsed, provided appropriate matching is used.

The alternative is to use separate RX and TX feed to the antenna. This is almost necessary anyway as there is a low noise amplifier at the antenna for RX.

The impedance of coax is different between RX and TX. 75 Ohm is best for RX. About 38 Ohm is ideal for TX. 50 Ohm is a compromise for both RX and TX.

http://rfelektronik.se/manuals/Datasheets/Coaxial_Cable_Attenuation_Chart.pdf

LDF4-50A, HELIAX® Low Density Foam Coaxial Cable, corrugated copper, 1/2 in

Cavity filter

I haven't seen a cavity filter used in EME, but few know about them. It could be quite desirable to have a pass band cavity filter very close to the antenna and before the broadband low noise amplifier. (Not all LNAs are broadband, some have filtering. Filter=losses?)

The LNAs are usually mounted at the antenna, but the loss of a couple of metres of coax (-0.3 db) to a cavity filter (-0.5 db) may be justified to give 30 db of out of band noise attenuation. This would greatly help in reducing overload of the LNA by such noise. With a filter it may/should be possible to use much more gain at the LNA. (and perhaps reducing the need for gain in the antenna?? but need antenna gain for TX!)

QSOs are usually done when the moon is near the horizon. As such, the antenna will receive a lot of terrestrial noise. The cavity filter will reduce some of such noise.

A high Q 70cm pass band filter is a little taller than a quarter wave length, 250mm, and up to 200mm diameter to give high selectivity. The same cavity can be tuned to its third harmonic to work on 23cm with high Q and selectivity.

It may be better to use a pass-reject filter as the sharpness is much higher than pass-band. The reject frequency is immaterial in this application. (No- tried it and pass-band better. Some LNA use small pass-band cavity)

The use of a cavity filter or two might be our contribution to EME practice. In a quick Google I found a discussion about using them but none on actually using them.

Many LNAs, especially high UHF have filters, stripline, sometimes discrete components.

LNA (Low noise amplifier)

LNAs used to be a major problem and a significant cost, however with cell phones and satellite TV, the cost has reduced dramatically. LNAs with a noise figure of 0.5 db are available for about $20.

We need a good source for a LNA with a filter if possible. (Priority) Ordered- L432LNA Down East Microwave.

http://f1chf.free.fr/F5DQK/3_Preamplis_LNAs/Preamplis_non_commutes.pdf 
http://eme.dokidoki.ne.jp/photo/jh0wjf/preamp/index.html- clear photo for cavity LNA.
http://www.ok1dfc.com/EME/technic/ATF54143/index.html
http://www.qsl.net/sv1bsx/uhflna-bsx/uhflna-bsx.html fhx35lg
http://www.qsl.net/dl5lf/432_preamp.html - cavity LNA circuit
FHX35LG- as used in cavity LNA- ordered 5 for $10 obsolete
ATF-10136- lower noise- ordered 5 for $10 obsolete
ATF-35143- even lower noise but surface mount

RX/TX switching

I have some BNC RX/TX relays plus the club has some too.

TRX

The club has an IC-9100 with 23cm. I have a IC-7100 to 70cm. IC-9100- 70cm 75W, 23cm 10W. IC-7100- 70cm 35W. Power might be enough for IC-9100, but will need amplifier for 70cm.

I think interfaces are similar. Both probably need firmware upgrade.

Could use 70cm transverter with IC-7300.

I have ic-7300 and numerous SDR RX and TRX. LimeSDR TRX with SDRangel might be good.

I can put a panadaptor on the IC-9100 or the IC-7100. They can be done either at the IF or RF after bandpass filters. http://vk4zxi.blogspot.com.au/2013/11/sdrs-at-first-if-of-trx-as-panadator.html  http://vk4zxi.blogspot.com.au/2014/02/new-trx-ic-7100-look-inside.html

Mode

WSJT-X. It is what I had in mind with the GPS RX DSP approach. The signal is sub-audible but can be dug out of the noise. It seems to have its own spectrum and waterfall, negating some of the benefit of the SDRs.

Getting WSJT-X to work on our TRX is a priority.

https://physics.princeton.edu/pulsar/k1jt/wsjtx.html

Band

70cm or 23cm seem the easier to try first. 70cm is probably preferred as we have the most gear for it and the components are't too small.

TX amplifier

The TX output of the IC-9100 may be enough. 100 W of USB Data?

My DATV amplifier is on 70cm and can put out more than the legal limit, although I do need to finish building it. http://vk4zxi.blogspot.com.au/2017/01/commercial-dvb-t-amplifiers-and-filters.html


Operating

Moon tracking seems achievable. Probably best to get echo working first. I think it can be done with the moon in any visible position.

Then try listening for signals, then try for QSO. I think this requires the moon to be in a particular place.


Tracking software

"I can't say enough good about GM4JJJ's MoonSked program (which is now 
freeware) and how it interfaces with the EA4TX rotor controller.


This is the setup I've used here at W1ICW since about 2011. It offers 
point and click tracking of the Moon, the Sun, and a variety of 
celestial noise and "cold sky" sources. It's really nice when I haven't 
been on in some time because I can point the array at the sun (or The 
Pleiades if the sun's not up) and see what I have for a noise rise from 
50 ohm termination. Gives me a good indicator of the overall health of 
the system. With the rotors tracking I can let the system run and act as 
a spotter for the liveCQ network while I am doing other things in the 
workshop.


I recall there is a "helper program" that goes between MoonSked and the 
EA4TX rotor controller software but I forget if it is supplied by GM4JJJ 
or EA4TX"


http://www.gm4jjj.co.uk/MoonSked/moonsked.htm



http://home.hccnet.nl/uffe.noucha/azrael/azrael.htm
MAP65 and TrakBox



EME links

Basics

http://www.g4ztr.co.uk/app/download/13284489/RaCcom_Feb14+EME+part+1.pdf Intro to EME
http://www.g4ztr.co.uk/app/download/13300096/Radcom_Mar144+EME+part+2.pdf
http://www.g1ogy.com/www.n1bug.net/operate/emebasic.html

General

https://www.dxmaps.com/eme.html Links to all EME.
http://www.moonbouncers.org/ It has papers and links to other sources for EME.
http://www.g1ogy.com/www.n1bug.net/index-2.html
https://www.dxzone.com/catalog/Operating_Modes/EME/

Hardware

http://www.minikits.com.au/index.php?route=common/home
https://www.w6pql.com/parts_i_can_provide.htm
http://2ingandlin.se/Feed_comp_432_MHz.html
http://www.ok1dfc.com/EME/432/it9cjc.htm Minimum configuration.
https://www.amsat.org/ mainly satellite but good.
http://www.rfhamdesign.com/ Ideas for dish mounts etc.

Email/Forum/News

http://mailman.pe1itr.com/mailman/listinfo/moon-net
http://www.nitehawk.com/rasmit/em70cm.html

Software

http://www.vk3um.com/eme%20calculator.html
http://www.n4rfc.com/?p=1419  Quick Guide To WSJT-X On The Icom IC-7100