Dec 31, 2008

New 430 MHz antennas part II

Finally a relay was found
The previous mentioned coax relay type CX520D was found, but it is way too large to fit inside the weatherproof box and have 3 N-connectors connected.
Some more digging inside the junk closet offered a smaller version CX120A. This one has direct solder contacts with 5mm coax entries. After several unsuccesfull direct plumbing attempts, I decided using 5mm teflon RG142 coax as pig tails. Perhaps costing some tenths of dB due to possible minor SWR mismatches, but then again loosing the N-connectors is already 2x 0.15dB (theoratically).
Ah forget about the dB-Bullshit; it will offer fine QSO's I'm sure!

Not the slickest looking solution, but done with care for reliability.
The IP66 plastic box outlets are weatherproof, but I added liquid rubber for additional protection.

The coldest night in Holland for 2008
Early this morning I found that the 430Mhz omni vertical was affected by last nights -9 degrees celsius frost. Our coldest night of 2008 !

That is not white paint but frost; see the close-up.

The coaxes are cut and have N-connectors.
Another antenna preparation ready for the soon-to-be antenna overhaul.

Dec 27, 2008

New 430MHz antennas

There's currently a lot of VHF/UHF antennnas lying around here. Some from fieldday setups, holiday/contest packet links, or just waiting for 'that new project'.
Well since there is very little activity in CW/SSB on 430MHz, I never got to setup a decent yagi at this new QTH. I'm not into UHF dx'ing anyway; my focus lies on 50/144. You can't do all bands, unless you spend (too) many time in the shack, right?
FM repeater dx'ing is something I do like and since I'm preparing new omni-verticals, I decided to add one of the available yagis to the new mounting bracket.

This is a Flexa type FX7044, 16el for 430-440Mhz. Boomlength is 3.10mtr. The Flexa Yagi, is extremely light weight (1.7Kg) and has the lowest windload on the market. Its 2mm dia steel elements are subject to discussion in terms of achievable gain, but for my application it is perfect.

The white spots indicate spray paint. It is a special spray paint which can be used on all surfaces and even rost. I'm using this for endured weather protectection, other plastic sparys etc. never did last very long.

What's next?
Both antennas connect to the same UHF rig, so a coax switch box is needed.
There must be a CX520D coaxial switch somewhere in that closet.....

Dec 4, 2008

CQWW CW 2008

Preparations at PI4TUE
To tell you the truth: not many of us were prepared for this contest. Domestic issues, heavy workload @QRL and stuff, prevented us from a decent preparation. However, Aurelio/PC5A did a great job in getting the clubstation PI4TUE ready on time. He had to climb the roof tower on friday afternoon before the contest, to fix the SteppIR, which again had a major tilt and azimuth offset. It just will not clamp.

We set up our only RX antenna, a home made portable K9AY, just 4 hours before the start of the contest in darkness. Initially it showed no directivity whatsoever. We could not find any error but noted that disconnecting the ground had no effect. The ground connection consists of a 1m copper pipe and 4 additional radials. Usually the ground stake is sufficient enough. Adding the radials makes this antenna even work fb at a rocky 2030mtr ASL mountain top. Upon examening the switchbox, a decoupling cap to ground proved open circuit.

Switchbox+common mode filter(blurry pic). Mark-IV version of K9AY switchbox undergoing repair. The shack of PI4TUE, being the student clubstation of the Eindhoven Technical University (ESRAC), certainly had lots of spare parts available. At T-30 or so, the K9AY showed a F/B performance of several s-units on some european stations. That's good , right?

Available antennas

  • 40m+80m dipole at 65mtr AGL
  • SteppIR yagi at 75mtr AGL
  • HF2V vertical for 40m/80m at 60mtr AGL
  • 2x 0.25 wave 160m sloper at 65mtr AGL, direction USA and JA
  • K9AY at ground level

Mark/PA5MW and Rens/PA3FGA during the night shift. Yes that's a 'capo', and a real one!

The new SteppIR performed very well; especially the bi-directional option was appreciated much.
Rens' Elecraft K3 #371(?) performed as expected; great RX on both main and sub-receiver. However, it showed some minor quircks: VFO A/B dropping out of sync, occasional strange offsets and during the first night a total backup reset via RS232 was neccessary to get it going again. Oh well... the firmware is still maturing and I have seen great devellopements during the last 12 months.
Operation-wise it's not my cup of tea. The Orion is a better (contest) rig; it offers far better manual control and view of all current settings. Next the Orion's antenna and VFO distribution and controls are clear and versatile. For me it sucks on the K3. We have been discussing several days on how to setup the K3 for true diversity and being able to switch back to "normal L+R" reception of RX or TX antenna's, without having to use more than a single button and certainly not having to enter (audio)menu's. On thursday I found a schematic on how to switch in/out from true diversity RX on both L+R ears, using an outboard antenna splitter on the K3 main and aux antenna inputs. This was cleverly designed by Bill W4ZV, who used to have an.......Orion :).

Ground connection on back of Elecraft K3 + common mode filters.
Next; one operator in desperate need for another espresso!

The David Clark headphones sure help in the noisy environment; since the PI4TUE shack also accomodates many local 2m/70cm/23cm/13cm FM repeaters, packet nodes, packet &psk31 links and zillions of network computers.

160m RX antenna performance at PI4TUE, or ..... the lack of
We have to do some more experiments since none of the tried 160m rx antennas has offered better signal/noise than our TX quarter-wave slopers so far, including this one. Despite the shown local F/B it did not offer any dx at all.
Over the years we have tried:

- KAZ on the north rooftop @60mtr ASL
- Magnetic loop on rooftop @60mtr ASL
- K9AY on the north rooftop @60mtr ASL
- K9AY at ground level, 110m north of the large shack building, 30m from a low building
- 160m short vertical at ground level, 80m north of the building
- K9AY at ground level, 180m west of the large shack building, 20m from a low building

K9AY & 160m short vertical used copper ground stake 1m + buried copper radials

The PI4TUE shack building is about 60-70m high, has a full metal frame on the outside. It accomodates a full size TX/RX 0.25 sloper on the west (dir. USA) and NE(dir. JA) side.
The above mentioned K9AY and 160m short vertical have been used at several other locations in which they performed very well with the exact same coax lengths and hardware. Difference is that at PI4TUE the coax travels from ground level along the building, some 50mtrs upwards to the shack room, 40mtrs away from the west-TX sloper. This long vertical travel will certainly not help making any antenna quiet.
This contest weekend , again we suffered from a RF noise level on the K9AY that no dx was heard at all. Is it local man made noise from the university buildings? The city environment? We will do a comparison measurement soon on a very short vertical, both at the university area as well as in one of our domestic field locations using a spectrum analyzer.
Both the TX slopers offer some reasonable F/B, thanks to the metal framework of the building. As such it was the best rx-antenna currently available.

Food, beverages, couch for crushing...

The next-door 'living room' with eat & sleep accomodations.
And Rens making true espresso or capuchino using Diemme ..something? I will do a seperate blog on his barrista qualities soon !

In no particular order: Aurelio/PC5A, Sjoerd/PA0SHY, Harry/PE2HD, Frank/ON9CC, Rens/PA3FGA, Mark/PA5MW.
And those who helped on friday afternoon/evening: Claudia, Steef/PA0IB, PA4A

From L to R: Aurelio, Sjoerd, Harry, Sam.

Was it fun?
Yes, it was fun as ever, being with hamradio friends together and contesting. 40 mtrs was just a-m-a-z-i-n-g. We need to pick up this momentum and go for the next contests in Q1 2009: CQWW160mCW, PACC, ARRL DX CW and ARRL DX SSB.

Band QSOs Zones Countries
160: 299 14 56
80: 496 20 80
40: 655 33 117
20: 919 34 115
15: 241 24 66
10: 0 0 0
Total: 2610 125 434 Total Score = 2,855,931

Despite only having a single "3-bander"yagi , some dipoles, slopers and verticals, being at +60m AGL does help. It is a privilege to use the schack and living room. Thanks to Sjoerd/PA0SHY, Steef/PA0IB and Martin/PA3DSC for their efforts they put in building/maintaining the PI4TUE/PI5HEV university clubstation.

untill the next one...

Nov 16, 2008

Give me a reason NOT to buy;

dynamite, a gun, barbed wire etc....
Possession is all strictly prohibited in our country.
All for many good reasons. But after our latest 'experience', reason is a bit lost here.
Oh well.... get over it !

Above picture shows the result of our burglar visit.

What happened?
02:30 AM; I wake up because of a crackling loud sound. I switch on a bedroom light and go downstairs to the living room. There I find nothing abnormal; all doors are correctly locked, all windows seem OK. So back to bed again. I sleep quickly, so QSY zzzzz...
02:45 AM; again this loud noise. Instead of going downstairs, I put aside the window curtain, look downside left at my parking see a guy in total black tight clothing, hand gloves and baseball cap. Upon detection he winks his fellow man and both run away quickly. There's an attempted burglary going on.
I jump into my hobby overalls, put on a pair of sneekers, open my front door and run into the direction they went off. I spent some 7 minutes looking at several cars, checking alleys and several roads.
It is not my intention to force a confrontation being alone without any arms whatsoever, but at least I want them to know that I do not just sit back and p*** my pants. And besides, I was being just a bit upset...

Burglar result
Using a 200m glass sucker, they tried to break the lock of the sash windows, which are on the side of my house where the parking lot is. They needed several attempts before the plastic window-chassis broke.
Only one lock of the outer windows is broken before they were detected while performing their profession.
No other damages have been found.

Police assistance
I call the alarm number at 02:55 AM and report the attempted burglary. At 03:30 they arrive, look at the window and enter my house to write a report. Upon their leave I ask if there have been any other attempts recently in my area; "no, not that we would know".
Later that day,I'm visited by two officers of the forensic research who take prints of the glass sucker and a hand glove on the second inner window.

Property owner action
Since I never open these windows, I decide to fixate the window permanently using glue. Next, I have cut some 25x25mm bars to block the windows:

More protection is needed; a Halogen floodlight with motion detector is mounted on the bottom of my antenna tower. It switches in after dark automatically.

The back fence can use an upgrade too; so I add a new layer of treated plywood. The most vulnerable part is done first. Next week I will do the rest.

Next to installing extra safety-locks, there are some more tricks&tips I will
be implementing this week.

Neighbourhood monitoring
A quick check at the closest neigbours revealed that there was a succesfully burglary 6 doors away, just the other week. Talking to these people and others across the street I learned that 2 more houses in our area have been victims last month. Would have been nice if there had been a short informing letter to everyone. Let's start doing that ourselves.

With regard to possible psychological effects

I experience no anger, extreme frustration or other negative effects. In fact I went to bed again 30minutes after the police left the house that morning. But I do understand very well that such might show up sometime. For now let's just say that at this point I regard the whole story a 'negative business encounter'; they want something from me, I want to avoid that deal as much as possible. I need to put more effort in my work there.
The story is different for my girlfriend though. Thank god she slept through the whole story. But she's seeing burglars everywhere and she hasn't slept well ever since. I'm doing my best to bring back that comfort to her.
Let's end this with the simple fact that there are other more serious issues in life and we will grow over this too.

If you have any tips or remarks, please feel free to add any comment

Nov 2, 2008

New omnidirectional verticals for 145 and 430 Mhz

The Half Wave Sleeve Antenna
This model acts similar to the typical J-pole designs; a 0.5 wave radiator plus a 0.25 matching section. However, the coaxial pipe or sleeve section in this antenna has a much better choking action. This should keep the coax free from radiating and result in a better radiation pattern. In theory that is.
The popular J-pole is easier to construct, but the brutal feeding of the (unbalanced)coax to the (balanced)matching section is questionable. But there are new, better variations of the J-pole.
And let's not forget; both offer plenty of fun as they are very efficient antenna's.

Bad alternative; the commercial 'collinear' dual-band vertical
OK, I admit; I have used these typical white fiberglass collinear constructions for years. Everyone has (had) one right? It is by far the most succesful commercial antenna for VHF/UHF. Offers plenty of QSO's too, nothing to bash about that. I still have a 'short' Comet GP3 VHF/UHF for portable use.
But as soon as SWR acts funny you start investigating what this antenna is all about.
What I do not like:
- collinear sections, having no true stacking distance, do not offer the "theoretically calculated" gain. Funkamateur magazine did a comparison between a single rod 5/8 home made antenna and various commercial collinear antenna's back in 2005. Even the super 3x 5/8 (5mtr high) offered no more than some 2 dB gain.....
- bad connection joints "offer" a variation in SWR in due time
- capacitor failure in the bottom section
- 3 metal spokes function as 'groundplane'
When opening up such antenna you find pieces of welding copper, matching coils and small ceramic caps.

The Sperrtopf (german) or Fietspomp (dutch) antenna
Actually this sleeve antenna was designed by A.B. Baily and described in u.s. patent #2184729 in 1937.
The german word 'Sperrtopf' refers to its coax sleeve section.
The dutch word 'Fietspomp' refers to what it looks like; a cycle-pump. I always found them very ugly to look at, but this is not about cosmetics but performance & durability.
You can find some more info on how to build your own at:

The 438-470Mhz Sirtel CX400D
I bought 2 of these a few years ago on a flea market. There's already one on my roof, see my blog of feb 24th.

To get them to resonate correctly in our 70cm UHF band section, I need to lengthen the radiator by about 6cm, or was it 8cm? Darn! Why do I forget to write down such evident info? My antenna analyzer stops at 30MHz. Well, l know someone who has an HP network analyzer AND makes great coffee. I will do a separate blog on his Barrista qualities soon :)

See above a really pathetic attempt to measure and adjust the radiator length. Surely the HT batterypack was near empty. And so was the reserve pack.
Let's finish this blog quickly and go to that coffee....

The Wimo 145MHz version offers a finished version at an extremely cheap price.
I pop-riveted the short alum mounting section to a clamp. A few layers of spray paint should ensure weather durability. The horizontal tube section is meant for creating a distance from my antenna tower, in order to get the best omni pattern. Mind you; I cannot mount this antenna on the top of the tower. Local restrictions do not allow this. Long story, let's not go there.
It is all about maximizing efficiency and setting priorities.

Where was I ?
Ah, time to get me that coffee :)

Oct 26, 2008

SteppIR @ PI4TUE - Part III

The final day of this project.
Me and my XYL went to her family
during the whole weekend, so again I was not able to join in. I had a great time in former Y22-country; enjoyed the superb hospitality, played with the kids of her sister etc.... Life is good, even without antennas.

Preparation for the last steps
More helpfull hands, safety tools, helmets, first-aid kit, everything to make this day a succes.
Again, you absolutely need perfect weather to work on a building roof at 220ft level. This turned out to be a beautifull day.

- Steef/PA0IB, Rens/PA3FGA, Aurelio/PC5A (wrapped in climbing gear)
- Assembling the prepared boom parts

- Tram trolley and protection against the existing guying wires by covering them with lengths of used plastic hoses.
- Steef/PA0IB assembling the control wires

- 6mtr add-on optional element
- Truss wire, not a luxury at such a height.

- 'Partly beam' just hoisted up in the air
- First-aid chick on standby
- Mind you; this is a small platform he is sitting on

- Lunchtime in the living room/kitchen/ contest sleeping room of the club station ESRAC at the 13th floor of the Technical University of Eindhoven
- L to R: Rens, Aurelio, Claudia, Steef

- adding elements
- "Look ma, no hands"

And then there's Murphy
OK, so what's different in the above second picture ?
The ground crew noticed a loose screw on the boom clamp of one of the reflector 'EHM' units. These had been loosened before to install the boom truss wire. Holy crap...!
So the whole ^%@## yagi had to be lowered again....
It is at this point that physical stress turned into overload as happened to Aurelio; suddenly his forearm muscles simply blocked and next his fingers were cramped-locked together. He got down and Rens took over.

- Switch of tower-operator
- Steef finalizing the control cable on the new Emotator FX1200 rotor

- On the left: HF-2V 40/80m vertical (not visual)
- SteppIR 3 el Yagi
- VHF antenna mast, including full size 40 and 80mtr dipoles
- Crossing the street-light; 160mtr sloper wire, barely visual

This final job lasted the whole day. Totally exhausted they left the premises at 18:00
During the week the antenna tested successfully ! This new antenna will certainly bring some new momentum in the coming contests.
In the meantime I have seen the antenna from ground level, it looks intimidating.

Again a job done very well guys !

Oct 5, 2008

SteppIR @ PI4TUE - Part II

Last weekend the 'next step'was taken in this project:

Remove the old antenna's from the mast on the roof
The picture below shows the roof of the building at the Technical University of Eindhoven. Not all antenna's belong to the contest station PI4TUE. There's plenty of antennas for FM repeater and packet and other digi-stuff as well.

Safety first ! Especially at a total height of more than 70mtrs above ground level (230ft). We have had to cancel several saturday options because of fierce weather (wind).
The top antenna is, sorry used to be a 5 element yagi for 50Mhz. The front boom part +director was already dissappeared; it simply must have snapped off at one point. The wind forces can be huge at this height.
The antenna below is a classic old Fritzel FB33 tribander + extra WARC dipole (12-17-30mtr).

This is Aurelio, PC5A, being happy as the weather is such nice for a change :)
Blueman +white helmet is Rens, PA3FGA.
The tribander came down easy, well too easily for one end-part of a director as it came lose and just dropped down. Nothing was hurt or damaged though. Upon close inspection several bad or loose mechanical/electrical joints were noticed. Now maybe this explaines the sometimes erratic SWR behavior we have experienced ?

See how the boom has bended over the years?

Time for a well deserved pause and some coffee.
The room is situated on the top floor and adjacent to the shack of PI4TUE. It has facilitations for making thee/coffee, has a fridge and besides the 'diner-table' lots of room to relax on one of the old couches.
From left to right: Aurelio, Claudia and Rens.
I'm pretty d*** sure the beer is a "leftover" from some other group !!

Next the Emotator rotor was removed. Its internal slip-coupling is totally worn out. A previous custom modification lasted for another year or so, and now it is in-operatable again. This one simply has served its time. Pity that the custom mounting plate for the mast was corroded and stuck. This will be a job for others now. So the new rotor will have to wait. Too bad, now the project is on halt again. Oh well, it will be quickly dark and cold soon after such a day of hard work.

This is how much space the new SteppIR will take up. The try-out of the assembly was done to prepare us for the future final installation. It is convenient working with these"pro's" who make optimal use of their time available at that day.
Why I am not in any picture?
I was doing shopping with my YL in Amsterdam.

Job well done, much appreciated guys :))

Upgrade vertical polarized yagi for FM repeater reception

Previously I have mentioned that I do like DX'ing on FM repeaters on 145MHz .
Not only both my transceivers have been specially upgraded for this (customized 455Khz filtering), but there is a dedicated vertical yagi antenna for this too. It is fixed at about QTF 160 in which I can constantly work PI3ZLB near the Belgium/German border on 145.725. During ducting propagation I can work, or at least hear other repeaters on that same frequency from Belgium, Germany and Luxembourg:

Repeater Near city Locator QTF QRB
PI3ZLB Geleen JO20WX 153 78km
ON0NR Namur JO20KJ 195 139km
LX0HI Bourscheid JN39AV 166 196km
DB0ZK Koblenz JO30SH 133 209km

The above vertical yagi antenna has been in use for more than 5 years now at different locations. It is a 4el '50 Ohm' direct feed version. The boom has been extended as the tower had a strong negative influence on the SWR. After the extension it worked much better.
Since I am planning an overhaul on my whole antenna system, this one needs some attention too. And while we're there, let's take it to the 'next level' right?

Old Flexa yagi's
At my old QTH I had a stack 2x 9el Flexa yagis's installed on my roof :

These were used for comparison to a single yagi having double boom length at the same height, mounted on a second mast. Total stacking gain was similar to the single long boom yagi, but the performance was slightly less. The wider horizontal angle(better for contesting though) showed more background noise.
My current location does not allow for a second tower/mast unfortunately :(
So both 9el Flexa yagi's have been lying around doing nothing ever since, actually rotting in the rain:

For those of you who wonder if these Flexa yagi's elements ( 2mm steel whip elements on extreme lightweight alumn) corrode on the element to boom contact, see below:

After 8 years of use this looks pretty corroded to me.

Rebuild to 5 el. FM vertical yagi
I decided to cannibalize one of them and rework it into a 5 element vertical yagi with offset mounting.
Time to do some serious cleaining & polishing :).
I just cut the boom and mounted the first 5 elements of this 9el design only. SWR measurements showed right what was expected.
Next, the boom required an extension for both the offset mounting bracket and the required extra distance from the tower.
I planned to insert a piece of the right alumn tube for the connection between the two boom pieces. The first few cm's go easy, but after that it's a tough job. The alumn insertion tube quickly grinds to a final stop. For durability I was planning to mount a parallel piece of boom anyhow, so after a sunday's afternoons job we get the following result:

Flexa yagi's have received a lot of critical remarks in the past about the (too) thin 2mm dia precious steel elements. I don't care about the 0.5dB discussions, all I see is its current merits:
  • Extreme light weight
  • Visual unobtrusive
  • Low wind load
  • Thick, high impedance dipole + balun
Can't wait to get this one it up in the air :)