Your own HF multiband vertical
During my first participation in the annual HB0-PI4TUE mountain dx-peditions back in 2003, I found that by using a fishing pole and some wire, you could build a very simple quarter wave vertical. Just tape a vertical wire along some fibre pole, throw a few wire radials in the bushes and go for it. Adding a second vertical wire in parallel made it a multiband antenna. This newcomer's antenna was a bit mistrusted at first, against all other vertical aluminium on the premises.
But it soon proved very competetive. The other commercial trapped vertical, showed not only signal loss, but were more noisy on reception. From then on everyone wanted to use this 'new kid on the block' and the 'trapper' soon became the 'lone black sheep'.
From that summer onwards we started playing with the concept at thome and during field day set-ups. We wanted more bands along a single fibre rod, so why not make a 10-12-15-17-20mtr vertical using 5 vertical wires?
In order to avoid coupling between the radiators we used spreaders to keep them separated from the main rod. Many attempts and numerous antenna measurements using various analysers proved; mutual coupling is-a-big-deal. When we thought we finally had concord the animal we took our new 5-band design to the mountain the next summer. Up there it took 2 days to get the thing working..... :(
Some don't s on multiband verticals:
- anything closer spaced than about 30cm (1 foot) is prone to cause heavy coupling
- too many bands will not work; forget about 40-30-20-17-15-12-10
- not using a balun/common mode filter makes the coax just another disturbing radiator
- elevated radials double the trouble of coupling and adjustments
- do not expect that the ground radials act similar in another location
- do not expect that it will be reliable and still have the same SWR after some rain and/or wind
If you have plenty of time and patience, a lot is possible. You will notice that for a single frequency it will 'jump between radiators' and the same goes even more for elevated radials. You have to connect/disconnect wires every time to verify which radiator/radial is dominant. For a field day style setup another approach is required. After trying many designs, we now have some reliable repeatable ground rules.
Basics of the multiband quarter wave wire-vertical
Note: this is a tribander for 20-30-40mtrs
Vertical: 12mtr/40ft fibre pole
Wire: anything will do, start with a length just over 0.25 lambda
Spreaders: plastic about 60cm/2ft long. Used on both top and bottom
Radials: minimal 8 laid on the ground, either straight or in zig-zag shape
1:1 Balun: use any decent common mode choke (not in drawing)
Adjustment: start from the lowest frequency upwards
Since the rocky bottom and many plants/bushes on our mountain do not allow for many straight radials, we opted for 8 radials laid out in zig-zag shape. Each corner was fixed uding an iron nail. This created plenty coverage of copper nearby the radiator and is accepted to perform better as fewer longer radials. See also "Lowband DXíng" by John Devoldere ON4UN, or "Monopolantennen und Vertikalantennen" by Gerd Janzen.
First vertical; 12mtr/40ft fibre rod
Above vertical resembles the design in the drawing. It has 3 radiators for 20-30-40mtr band
A current balun was used with a toroidal core type FT240-K.
A 1mtr length copper tube was hammered down and served as ground radial connection.
BONUS:
- the 30mtr radiator length is close to 0.75 wavelength on 10mtrs.
- the 40mtr radiator length is exact 1.5 wavelength on 15m.
Both showed a good SWR pattern. It performed very well on 10 and 15m where the typical high angle lobes proved worthy during the rare european Es openings .
Second vertical; 6mtr/20ft fibre rod
This uses the same basic design, but has 5 radiators
Above vertical has radiators for 10-12-15-17-20mtr band.
The current balun uses a toroidal core type FT240-67.
A 1mtr length copper tube was hammered down and served as ground radial connection.
The small blue box is the clue for a former blog entry :)
Performance
Both antennas were pretty quickly setup. The minor adjustment changes were due to different ground environment from home.
Using these two multiband antennas we have made some 5500 contacts. They both perfomed very well. During the IARU contest we managed to make >800 qso's in an 18hour effort.
Operators found the antenna very competeteive on 40mtrs where we could run a frequency without problems every time we wanted.
Think about it; your domestic situation certainly allows for any this kind of antenna.
And its a full size performer, not to mention cheap !
We're back home again !
We have spent some very nice weeks in Liechtenstein. Enjoyed the great scenery, had delicious meals, walked the mountains, listened to music, slept day and night, build antennas, completely build a K2, played hamradio operator, or just did nothing particular at all :).
Some very nice moments are engraved in our memories.
Where did we go exactly?
Location: Bergstation Sareiserjoch (2000mtr ASL)
City: Malbun (1600mtr ASL)
Country: Liechtenstein
See their website: www.sareis.li
Or check the webcam: http://livecam.feratel.at/cam/malbun/4135/index.jsp
So how did our newly build 7 el/50MHz yagi do?
Building yagi's
First the old reliable 5el/50MHz was setup on the cabin's 15mtr alumn mast. It is a 4.5mtr boomlength DK7ZB design. Form left to right: Aurelio/PC5A, Rens/PA3FGA, Mark/PA5MW.
Next we installed a portable alumn mast on the top of our mountain. The mast was being completely rotated. This required a top support bearing and a rugged construction at the rocky bottom to fix the rotor.
After many blood, sweat and sunburn, the antenna was finally raised late in the evening.
The coaxial feedline consisted of 20mtrs Ecoflex 15 (15mm diameter) and some 30mtrs hardline (35mm) into the cabin shack. Despite all these extreme low loss cables the new 9mtrs boomlength 7el long yagi antenna(design PA3FGA) was almost dead quiet, especially when compared to the second 5el yagi. The smaller front lobe and carefully designed minimal side/backlobes offered a lethal point & shoot antenna.
The 6m shack consisted of (from left to right): Create RC5A-3 rotor for 7el yagi, N1MM on laptop, Icom IC-746 inc Inrad filters +some mods, CDE Rotor for the 5el yagi, David Clark stereo Headphone, Bencher CW paddle, Kenwood MC-60, home made XXXL footswitch for PTT. The dx-cluster information was supplied via our local Linux packetnode (see earlier message june 10th).
And did the 7el/50Mhz work?
Yes it did!
Besides seeming 'dead quiet' it simply offered great dx which could not or hardly be heard on the smaller 5el. Now that is no real A/B comparison since the 5el is near the cabin (man made noise) and some mtrs lower. Anyway, we were ashtonished by the performance of the big-beast (portable, mind you !).
Switching between both antenna's showed between 6 and 10 dB difference (what's in a number) according the stations we worked.
Weak (tropo) signal performance was simply stunning; almost every spot in Europe could be worked somehow whereas the smaller 5el showed nothing but noise.
Some statistics:
>620 QSO's on 50MHz
>50 countries
Callsigns used on 6m:
HB0/PC5A (op: Aurelio)
HB0/PA5MW (op: Mark)
Despite being near the end of the Es season we worked caribic stations like 9Y4, PJ2, KP4, KP3. We managed to get easy through the big EU pile-ups on first or second call. Some USA stations even have been worked during night hours. I worked dx I would only dream of at home. What a difference with all 50Mhz antennas we have tried there in the past!! Size does matter.
Bergstation Sareis, Malbun, LI. (HB0)
From left to right: weather monitoring station, 7el/9mtr 50MHz PA3FGA yagi, 5el/4.5mtr 50MHz DK7ZB yagi, 20mtr commercial mast for domestic emergency communication.
Thanks to all of you who worked us !
My holidays have finally started; spend time in the shack, do the garden and visit a barber.
Time to do the Icom 746 alignment
Goal: check/optimize receiver adjustments.
Some 5 years ago this rig has been upgraded with INRAD SSB and CW filters and the RX gain setting was changed.
The master LO is dead on 60Mhz, showing 8Hz offset. The Philips PM6615 frequency counter (incl txco) was calibrated >5yrs ago. It is within 10Hz from the Marconi 2955 which was calibrated when I bought it in Germany in......ooh well!
What settings were re-aligned?
- LPL VCO Lock voltage; level at 1.84V instead of 2.0V
- RX peak L241
- Receiver total gain; setting from '38' back to '32' (about 30deg. on the potm)
All other adjustments proved within specs.
The software menu adjustment procedure was skipped; s-meter settings and stuff do not make QSO's.
Hooked up the 746, just in time to work TO5E (st Barthelemy dx-pedition), COOL!
Pity my logging software(DXBase 2006) is so difficult to upgrade with new countries; already 3 not recognized: E7 Hercegovina, 4O3 Montenegro and the TO5.
Time to collect stuff from my garden-house:
From left to right:
- 5el +boom parts 6m DK7ZB home made yagi
- 10m fibreglass DJ6NI pole for K9AY setup
- 10m Alu mast (70mm bottom, 35mm top)
- Comet GP3 2m/70cm packet antenna
- Rotor cable
- 'Tool' to find clear HF frequency, manage pile-up etc. :)
Good propagation today on 6m!
This morning, while eating my cereals, I worked Man JL8GFB on 50095.5 He was in and out the noise but very LOUD. I touched him on a few occasions but due to QSB he copied my callsign only partly. With some patience I wkd him during his peak some 20 minutes later. Check out his breathtaking setup at:
http://air.ap.teacup.com/jl8gfb/
6m band is exploding today; zillions of signals calling asia and many other directions. Just wkd CN & CT3 which brings the country total at 46 for 2008.
Preparations for another summer trip to Liechtenstein (HB0) are runnning fine.
One of the things missing at our mountain top location on the "Sareiser Joch" in Malbun(www.sareis.li), is an internet connection. Disturbing how quickly you get used to that common luxury when it is not availably for a change. A Long, (very) long time ago we started with pen & paper log but got quickly spoiled by the DX option in N1MM logging program :)
In the past our group (HB0/PI4TUE) has always succesfully used a packet link, which provided dx cluster info and, entry to relevant convers chat channels. Unfortunately our packet-node mini laptop (toshiba Libretto) from Gert, PG5D died 2 yrs ago. We were desperately in need for a new setup.
Personally I very much dislike anything related to soft/hardware programming. But one great advantage in group dynamics is that there's always someone who does like this stuff and will go to the bottom to get such working.
What is needed for our local packet node setup?
- Short 430 MHz Yagi Antenna
- TRX with 9K6 capability (Kenwood TMD700)
- Laptop with AX25 Packet Node on Debian Linux OS
- Wifi Router/USB-Hub Philips
How to build your quick & dirty 430Mhz Short Yagi
Cannabalize an old UHF TV antenna and re-use its boom and mounting bracket.
Find some alumn pieces and cut them to the required lengths according a 9el design on DK7ZB's website. Next, cut some trespa pieces and 'pop' them together with the elements to the boom. Now use any water resistant(Class: IP65) wiring box from an electronics store for the dipole. The balun/impedeande transformer is made from 2 pieces 0.25 wavelength 75 Ohm coax.
All done in a saturdays afternoon. Can't be more simple than that, now can it?
The mast is a fibre type. At only 4mtrs height in the middle of a small village, it receives the packet provider PI1EHV on 430.925 at 22kms distance, loud enough for a probeabely solid AX25 connection.
Test setup
We're up and running! Nice to "hear" that vintage 9K6 noise data connection on the 70cm TRX again.
Compliments to Rens, PA3FGA who spent 3 weeks building & programming the whole setup including the antenna.
The dx-cluster runs on the above old laptop packet node on the left. From N1MM on the wirelless connected client laptop on the right, we can setup a packet link within seconds. Three different laptops have been tested simultaneously and work perfect.
I'm getting in that dx-pedition mood again :)
What is next?
- Build a time server so all N1MM client laptops run the same system logging time
- Rebuild the 5el 50Mhz DK7ZB yagi
- Build a new 50MHZ long boom yagi ??
- Rebuild and test the old K9AY
- re-align the IC746 and do the IC151 mod
- etc..etc..
Note: this is a tribander for 20-30-40mtrs
