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...