26.5m 80/40/20/10 EFRW
Went with 49:1 on a FT82-43 toriod with 3:24 ratio and a 120pf 500v mica cap (that was what I had) with 26.5M of wire.
Intentionally selected a length with no half waves. 26.5 m = 87 feet. (https://udel.edu/~mm/ham/randomWire/)
http://www.qrpkits.com/sota.html with 19.5 m wire and counterpoise
Trap 20/40 Dipole based on SOTABeams pico traps – https://www.sotabeams.co.uk/pico-traps-kit-pair/
Trapped end feed also based on pico traps.
QRPGuys Portable Tri-Band Vertical Antenna – https://qrpguys.com/qrpguys-tri-band-portable-vertical-antenna
Looking for a DX antenna for S2S evenings. A 20m vertical appears to be the answer.
This will rock for 20 and 30 but doubt 40 will be much chop.
Got the switches 2m off the ground.
Had to keep the forth radial as it reduced swr, actually it flattened it. So three radials one down each guy and the forth just hanging down. Actually except you need the squid pole its quite a compact sturdy antenna.
Spreed the anti with clear acrylic
Tuned each segment with the VK5JST tuner. Also ordered the W8TEE and K2ZIA Antenna Analyzer – https://qrpguys.com/w8tee-k2zia-antenna-analyzer
20082017 – VK3/VC-018 Mt Bunnyiong
VK1 SOTA activation day and a test run for miniHFPA HF Packer Amp.
Noticed the alerts going up for VK1 2017 Winter SOTA Party so decided to go to local summit to play SOTA one what looked like a reasonable day to go out. Propagation recently has been terrible for NVIS so decided it was time to test my newest toy, a miniHFPA HF Packer Amp. This is a 35 watt linear amplifier designed for portable operations.
Decided to a to build a lightweight amplifier that can be backpacked to sites and be powered by a light weight LIPO 3S battery. Did look at commercial options. There are several out there a assembled Chinese unit and there are several kits available from eBay but appeared not to have adequate filters and lacking harmonic suppression. Glenn VK3YY describes building a unit based on W6JLs designs. There are a lot of kits around which would be more accurately described as harmonic generators.
I went for the HF Packer kit. I have decided to build as much as I can and not being a electronics engineer more that happy to assemble kits. The new 35w kit was announced and I put my name down for a unit. Not the cheapest options but was expecting a unit that was well designed and meet the conditions of my licence
The build went well. The biggest issue I had was using unleaded solder. My fixed temp iron was not hot enough. A new variable iron fixed the issue and the build progressed. Once completed had issues completing the testing process. The issue came down to incorrect marking of the RF ports. Once addressed (Thanks David) the device leapt into action.
So going from 5w to 35w output is a gain of 8.45dB. Given 6dB is a S point expecting an additional 2 sS points for my signal reports. VK7CW and VK2YW gave me a 599 with the amp in use.Off top a great start. Later without the amp in use I received a 559 from VK2WP. None of the contacts were soliciting reports as my CW is only good for making contacts not setting up experiments. Pre roll over SSB contact with VK1CT received 59 and post received 45. No one described poor signal so very happy with results.
At 717grams it won’t be a frequent addition to SOTA activations but when conditions are not good and the trek supports the additional unit and battery 35W it will be available.
The 4500mAh 3S 30C LIPO was at 80% after hour of use. Time for new batteries so will be going for a 2500/3000 mAh unit.
So the next is to develop a suitable antenna. Used a trapped 20/40 unit based on SOTABeams 100w traps for this activation.This unit is too heavy for SOTA however so looking at options.The AMP is rated at 35W for 60/40 & 30/20m bands. Will need a resonate antenna to avoid carrying a tuner so looking at a EFHW (End Fed Half Wave) instance. There is a lot of information out there. David VK3IL page describes a similar quest he went on and a search of the SOTA forum search pointed me towards HB9TVK. Thinking of using T80-6 for traps and a T140-43 for the matching transformer, RG178 coax and lightweight wire. Yes looking at grams here and the trap weight has to be trimmed else the wire will sag too much and can’t be seen on a summit with a sagging antenna!
More on antenna as options are finalised. Also will be building a CW radio for wet harsh conditions. Ordered the QRP-Labs single-band 5W CW transceiver kit and will build into a waterproof case.
160 to 6m Endfed for Portable deployment.
This is a big antenna and will not be suitable for tight summits. However ideal for Alpine summits.
135 feet or more then 42m appears to be the go.
7M squid pole holding top at 7m. Yellow cord to keep tips 2m off ground.
guy on squid pole
RF choke on RG174. 8 turns so can use 10m shield as counterpoise.Ends held in place with cable ties then covered in heat shrink tubing.
End Fed – http://vk6ysf.com/longwire_antenna.htm
VK6YSF 9:1UNUN http://vk6ysf.com/unun_9-1_v2.htm
Emergency Amateur Radio Club of Hawaii (EARCHI) 40m to 6m Endfed antenna using a 9:1 match. It consists of 30ft (10m) of wire fed into a 9:1 UnUn (Unbalanced to Unbalanced).Plans for the Antenna are available from EARCHI’s website
Counterpoise lengths appear to be quarter the lowest band so for 160m will be 40m. The ideal radiator length is one that avoid harmonic multiples (1/4 or 1/2) of the operating frequencies. Why is this not a dipole ? High impedance to support multi band operations. Here are the sites that describe the radiator lengths;
I have been using QGIS to geo-refeence maps in preperation for a new SOTA association. More on that later but the tool is a powerfull one and worthy of closer investigation.
Have PDF Maps Android on iPad and Android tablet. This app allows you to navigate using the tables GPS and overlay on a georeference PDF.
So the idea is to use base information to create custom map of the areas around and access to SOTA summits using a table with GPS to assist with navigation.
THIS IS NOT A PROCES TO REPLACE A GPS OR AN EXCUSE FOR NOT CARRYING A BACKUP MAP. It is a process that allow you to create a custom map and dispay on your favourite device .
I intend to use to provide a overview of a new area.
Keep that in in mind there are a lot of maps are available in geopdf format , both free and nominally priced in the Avenza store. It will be cheaper to just buy some maps and there are free overviews available for VK3 national parks from parks Victoria.
But, I have a few maps that I have notated with trails that are not georeferenced that I’d like to use. But for those cases when the map you want isn’t georeferenced.
GeoPDFis a unique data format that brings the portability of PDF to geospatial data. A GeoPDF document can present raster and vector data and preserve the georeference information. While GeoPDF is a proprietary format, we have a close alternative in the open Geospatial PDF format. GDAL has added support for creating Geospatial PDF documents from version 1.10 onwards.
Assuming you have installed QGIS. If not follow QGIS install instructions
Creating the PDF file
Prepare the image.
Several ways. Depends on your site and available tools;
Use Garmin BaseCamp to create a map and use the print process to open in preview then save as a TIF file.
or use Forest Explorer for Victoria (VK3) maps.
Create georeference data.
Open Qgis, select Plugins -> Manage and Install Plugins… Make sure that gdal and georeference plugin are checked. Select Raster -> Georeferencer -> Georeferencer In the Georeferencer select File -> Open Raster and open your tiff file. It will ask what CRS or coordinate system to use. This is the coordinate system in which you will be selecting georeferencing points.
Whilst will print the map with UTM coordinates overlayed I will use landmarks and lookup a lat/lng useing: GDQ (EPSG:4283)Set Basecamp preferences to Lat / Long ( dd mm ss.ss) and Datum to WGA-84
Now, you want to find points in this image that you can assign a coordinate to. If your image has grid lines, it’s easy. Use SOTA peaks or other major landmarks such road intersections. Find these same landmarks in Google Maps or Google Earth. Mathematically, you’ll need a minimum of 2 points spread both horizontally and vertically. I use six. One in each corned and usually two SOTA peaks.
For each of these points, use the ‘Add Point’ tool* to select your landmark and enter the coordinates.
* One of the buttons on the top has two intersecting lines and a yellow star, that’s ‘Add Point’
The Qgis georeferencer is supposed to be able to create the geopdf, but PDF Maps just says its an incompatible file. Instead, there’s a button that will give you the command-line switches to apply the georeference data with. We will use this information manually.
Select Settings -> Transformation Settings –
- Transformation Type: Polynomial 1, 2, or 3 (I haven’t experimented with this, but aparently effects accuracy of highly distorted maps.
- Resampling Method: Lanczos (This is supposed to be the best but takes longer to compute, I haven’t noticed a difference)
- Output Raster: output file name (required by the software, but we won’t use it)
Target SRS: output coordinate system (again, required by the software, but we won’t use it)
Select File -> Start Georeferencing… This will update the table on the bottom. The residuals will tell you how much in agreement the coordinate are in. This should be 1 few pixels or less. If not, there is someting wrong with the points entered earlier.
If all looks good, select File -> Generate GDAL script. Copy this script to a text editor.
Georeference our image.
Now it’s time to build the command line that will create the file that you need. To apply the coordinates, copy and paste all of the “-gcp x_pixel y_pixel x_coord y_coord” values into thetag below and run on your command line:
The command is;
>> gdal_translate -of GTiff -co “PROFILE=GeoTIFF”file1.tiff file2.tiff
and the GDAL script contents are;
gdal_translate -of GTiff -gcp 744.396 464.369 144.01 -37.691 -gcp 82.9136 96.7649 143.88 -37.6279 -gcp 1236.41 115.708 144.106 -37.6307 -gcp 1268.16 970.721 144.112 -37.7784 -gcp 239.069 745.448 143.911 -37.7397 “/Volumes/Data/maps/PDF SOTA/LocalArea.jpg” “/var/folders/h4/m6pmtkcn0mv7tlxp39jcxkwr0000gn/T/LocalArea.jpg”
gdalwarp -r lanczos -order 1 -co COMPRESS=NONE “/var/folders/h4/m6pmtkcn0mv7tlxp39jcxkwr0000gn/T/LocalArea.jpg” “/Volumes/Data/maps/PDF SOTA/LocalArea.tif”
so the command becomes;
>> /Library/Frameworks/GDAL.framework/Programs/gdal_translate -of GTiff -co “PROFILE=GeoTIFF” -gcp 744.396 464.369 144.01 -37.691 -gcp 82.9136 96.7649 143.88 -37.6279 -gcp 1236.41 115.708 144.106 -37.6307 -gcp 1268.16 970.721 144.112 -37.7784 -gcp 239.069 745.448 143.911 -37.7397 LocalArea.tif file2.tif
Now its time to apply all of the geolocation data, using the same EPSG number as was used during georeferencing. In this case as we are using WGA-84 it is EPSG:4326;
>> /Library/Frameworks/GDAL.framework/Programs/gdalwarp -t_srs EPSG:4326 -r lanczos -co “PROFILE=GeoTIFF” file2.tif file3.tif
So now you have a gereferenced TIFF file. We want to convert the TIFF file to a pdf so;
>> /Library/Frameworks/GDAL.framework/Programs/gdal_translate -of PDF file3.tif georeferenced.pdf
So lets go over again;
allen:PDF SOTA allen$ /Library/Frameworks/GDAL.framework/Programs/gdal_translate -of GTiff -co “PROFILE=GeoTIFF” -gcp 741.478 1080.39 146.061 -36.8556 -gcp 1048.45 1172.42 146.093 -36.8611 -gcp 1061.06 121.024 146.094 -36.7719 -gcp 1552.72 2274.25 146.142 -36.9572 -gcp 115.555 1930.09 146.001 -36.9278 06062016-1.tiff file2.tif
Input file size is 1905, 2375
0…10…20…30…40…50…60…70…80…90…100 – done.
allen:PDF SOTA allen$ /Library/Frameworks/GDAL.framework/Programs/gdalwarp -t_srs EPSG:4326 -r lanczos -co “PROFILE=GeoTIFF” file2.tif file3.tif
Creating output file that is 2063P x 2260L.
Processing input file file2.tif.
0…10…20…30…40…50…60…70…80…90…100 – done.
allen:PDF SOTA allen$ /Library/Frameworks/GDAL.framework/Programs/gdal_translate -of PDF file3.tif georeferenced.pdf
Input file size is 2063, 2260
0…10…20…30…40…50…60…70…80…90…100 – done.
Whilst the End Fed is convenient aerial as only requiring a single point and the squid pole, it has never performed as well as a dipole.
With the marginal conditions we have experienced as of late my thoughts wandered to going back to the dipole.
I converted my original dipole to a 20/40 trapped dipole rated at 20w. This works very well but a heavy unit with 18G automotive wire and 10m of RG58 coax. Always in the search for lighter options so decided to make a trapped dipole using lighter traps and wire. I always use a balun at feed so also seeking lightweight options.
SotaBeams releases a range of ‘PICO’ traps and light balun kits rated at 5W. As my activations are within this range, it was obvious what was next. Still had some ‘Unicorn’ wire stashed away so ordered the Pico traps and Balun from SotaBeams and waited for delivery.
Here is the finished product. There is not much to see as PICO is the operative term. Note the lack of bend in the 7m heavy duty squid pole.
Making the Balun consists of twisting the wire, winding through the toroid then attaching the coax. Quick check to ensure all connections are good then turn attention to the traps. Instructions for – PICO Balun.
Traps took a lille more time. Only because it pays to get it right. I had to add a extra turn to the instructions to get resonance as 15 turns were too low. Decided to use ‘Liquid Tape’ to protect the units instead of wrapping heavy tape around the units. Instructions for – PICO Traps.
Once done its time to assemble the antenna. Straight forward process. Attach 5.5m of wire to balun and take outside setting up on the pole and carefully trimming the wire until happy with 20M legs. Once completed attach the traps check, then add another 5.5m of wire and trim down until 40m is right. 5.5m is a bit long for 40m as the traps load the leg so next time will start with 5.1m legs.
With 10m of RG174 and a winder, the dipole comes in at 260g. Still heavy so may take 3m out of the coax.
Initial tests are very positive. Time will tell as to durability but happy with the result so far.
Currently looking for a antenna for chasing HF SOTA and WWFF activations. Domestic and DX. Mind you the distances involved with domestic activations would qualify for DX anywhere else in the world.
We are on 4 hectares (10 acres) out out town so not under the height or space restrictions most are use to.
So first thoughts are of gigantic towers holding multi element beams. Hmm a hams dream. Such instillations are not cheap.
What do I need ? Basically chasing DX. This appears to to be a activity that throwing a heap of money at will not solve. So yes beams and tall towers are a option but for now a modest full size wire antenna will be deployed.
Antenna are a compromise.
Currently have a 80m dipole and a MJF-969 tuner. The dipole is above the house. So apart from the length basically a poor configuration not taking advantage of the available space. The wire dipole works well. 40m on weekend is a case of waiting untill the portable stations are resolved then calling. 20m if you can hear them they can usually hear you. Noise takes me out on the receiving site. CW helps here.
The dipole is directional. A omni-directional antenna is desirable.
Being in the country we are away from the HF noise prevalent in todays environment so don’t have to deal with all that. Not ready for a beam antenna. I can setup directional wire antenna as desired. Most of my transmttion is whilst portable. Chase portable from home on weekends and listen at night when I can.
Portable activations have taught me that for a effective antenna there are a couple of basic points to consider;
- When propagation is poor it does not matter too much what you are using.
- The more wire you get up the better.
- The wire has to be resonate. (The 21m end fed for 20/40 breaks this rule but thats HF)
- Not to worry about the trees as they have little affect.
- Balun to match at feed point
Initial plans were to cover only up to 80m. However if your going to go to the trouble of running the wire then may as well go as big as you can.
Recently upgraded to advanced licence so now can access more bands. Current Band Plan – September 2015. A full size loop at the lowest band I can operate on seemed relevant. 160m loop will be harmonically related to 80,40,20,and 10. See radiation patterns for the loop.
No 30,15 or 6m support. A 60m loop would address that. 12 and 17m would be best addressed with dedicated device. One thing at a time.
A full size horizontal loop of 160m was selected.
Ok well done. Where to put it. Placement factors;
- Antenna not to be seen from the house.
- Actually from the deck
- Discrete feeding
- not visible
- not creating a hindrance for access
- transmission line under ground
Feeding the loop will be the interesting part. I intend to use coax to the feed point. The majority of articles describe a ladder line fed loop. Ladder line is involved in the matching process. I have a 450 feed wire antenna initially for JOTI using 100w and the MJF tuner. Basically connected to tuner using a 4:1 match. It was this antenna I used for my first SOTA activation. Still use when camping. This antenna is not resonate and the feed used as a part of the antenna. This antenna works but no better that the full size dipole.
Going forward of the house will involve negotiating the septic or being above the solar cells. Not desirable.
A position behind the house feed with coax underground was selected;
The loop will have a feed impedance of 125Ω so will use a 2.5:1 Balun to match to coax.
Quality low loss coax that will support VHF/UHF should a small directional antenna be desired in the future.
LDF4-50 1/2″ HELIAX Coaxial Cable was selected;
- 5.02dB/100M loss @ 500 MHz
- 1.17dB/100M loss @ 30 MHz
- Velocity Factor 88%
N connectors will be deployed.
The existing MJF-969 tuner will resolve any mismatches. The existing dipole will be taken down.
There are a lot of options put there. Even towers for free as long as you pull down and transport. I had already obtained 5 X 2m triangular sections. This was location from Ballarat so able to drive in and load into trailer to bring home. Initially seen as a tower of VHF antenna but seamed suitable to act as a base for a loop or two.
Layed 90mm storm pipe for coax. Ran 60m of 1/2″ Coaxial Cable through to the tower. Laid a concrete base.
4 sections of the tower are up bolted to the concrete base with three guys at 6m. It is square, the photo not.
This with the coax laid will give me 8m of height fed to the lounge.
Planning on running 170 meters of wire all up as want to be at the lower end of the bands. Proposed length should cover harmonic of the HF bands;
|Freq Mhz||Length Feet||Length Meters|
Measuring the length involved a new tape measure and marking every 10m until done. First run came up with a resonate loop of 1.65 Mhz. Too low. Took 10 meters out and ended up with the tighter but still too low as resonate at 1.750 Mhz;
|Freg Mhz||Length Feet||Length Meters|
There are still points where the wire is touching the trees. Not a big issue as insulated but don’t want the drag. I’ve broken the handle for the chain break so chainsaw is currently at the service centre having this replace and receiving w well earned service. Will address the remaining branches once back.
First response is extremely positive.
Comparing with 80m dipole with 160m loop and there is no computation. The loop is noticeably quieter and 2 to 3 ’S’ points better on receive. VK6 stations are S4 than can not be worked on the dipole.
The TS850 internal tuner addresses the main HF bands with no fuss. 30m is a challenge but 12 and 17m resolve Ok.
So far very happy. More to do to finish but thats all for this week.
Started with the sub 600G SOTA Station and keep adding equipment.
- MTR v2 – 125g
- Pico Paddle – 40g
- 850mAh Zippy 25C 3Cell LiPo Battery – 97g .
- END Fed LNR 40/20/10 – 216g inc m RG213 coax and winder.
- Notebook 220g. Also contains copy of licence and ID.
- 6m Mini-Pole – 300g. Can’t rely on there being trees
- Total – 998g
Of course that is not the entire kit you have to carry. Additional equipment for safety;
- GPS etrax 30 – 165g
- Camera 300g
- VX8r – 280g
- SPOT device – 120g
- First Aid – 600g
- Bivvy Bag – 382g
The pack with ready to go including 2.5L of water, apples, jacket and hat comes in at 6.5Kg