2016-12-05

Antenna for 30 - 80m

The weather has been cool to cold, but a milder spell made it possible to set up a simple antenna for the lower bands.

The antenna consists in a vertical part about 15m long, a telescopic fiberglass with a wire attached, supported inside the branches of a tree, and a few horizontal wires as "radials".

Right now I have 2 wires one is about 5.5m and one about 25m long. at the feedpoint has a 9:1 UN-UN (transformer). The wire lengths are intended to have the feed point at approximately 1/3 wavelengths on 80 resp. 40m. Not perfect, but workable. The tuner built into the IC-7600 tunes at 30, 40, 60 and 80. The high end of 160m is difficult, but it *does* tune.

At a later stage I expect to have some DC power  fed to a tuner at the feedpoint, and get some real radials into the ground (and possibly a few above ground, but the winter weather will probably make me wait until spring to do that. I would expect better results from that combination, but for now, since last night I have worked a bit of DX on 30m and signals are pretty good on 80m and 40m, for local (European) signals it is nicely comparable to my dipole, but for DX more tests are needed. I do not expect miracles, but some DX should be possible on the low bands now.

The vertical part is placed in between the branches of a few trees, so the antenna is fairly unobtrusive, though not really invisible. It will only be noticed if you know what to look for.

Update :

A fault was corrected in the system, resulting in a sufficiently low SWR on all bands 80 - 10m not needing the tuner, and the SWR on 160m being less than 2.5, making it tunable with the built-in tuner of the IC-7300. Very nice. 

2016-11-04

QSL-net page.

I have created a simple web page at www.qsl.net/<callsign>/ . The page will also point to this blog.

The page also comes with an email address - <callsign> at qsl dot net.

It is quite possible that the page will be expanded with info on a few of my projects. Time will tell ...

2016-09-01

Camouflaged Antenna up and Running

We have had some dry weather, so here is some antenna activity :

My R-6000 antenna has been spray painted green, and with some assistance from OZ7OVE and OZ1LH is now mounted with the feed point at 6m height.

Two days later I moved the antenna (alone), it took much of a day, in order to avoid destroying anything, and started camouflage painting mast pieces I have for the next antennas to be erected.

The improvement due to the height is noticeable on the higher bands, although the 6m signals from the R-6000 are still weaker than on my V-2000.

Update : Picture : The contrast between a camouflaged and non camouflaged antenna :


And - the signals from my 4m antenna changed. With two local stations about 20km away one got a bit stronger and the other a bit weaker on 4m.

Looks like I will have to do some 6m antenna building activities later.

Next up for a paint job is my 4m antenna, and that one will hopefully be mounted a bit higher than it is now.

Before the winter season I should be able to run all bands from 80m to 70cm in some capacity, possibly also 23cm. The HF dipole antenna should be back up and combined with the cable for the 4m antenna (yes, with a diplexer or triplexer). Some small 2m/70cm verticals should be mounted discreetly for local QSOs, and possibly I will use one of them as a pure receiving antenna (likely a short out-of resonance 3 band 2m/70cm/23cm vertical).

2016-08-20

Paint Test for antennas.

I got cables made for the test, and got two antennas tested in my garden. Fortunately the weather kept dry for the tests.

Test setup :
Signal generator,
Test antennas, mounted on a 3m mast :
- 10m half wave vertical
- 6m half wave vertical
3 RX antennas .
- The R6000 on a 3m mast antenna in the other end of the garden
- The V-2000 antenna a bit closer, but at 6m
- The 4m half wave, not far from the R6000, also at about 6m

I had intended to use a R7100 RX, but the s-meter had far too much drift, probably due to heat, so that was discarded, I was then using my IC-7100 and IC-7300 in the shack, with a combination of the aforementioned antennas. Much more stable S-meter readings.

The paint is purchased from a military surplus shop, and is spray paint. One can could cover the two antennas.

No significant difference could be detected in the signal levels on either 10m or 6m. The paint had been approved by me for reducing the visibility of aluminium antennas for HF, 6 and 4m. More paint has been ordered.

When I get my R-6000 antenna for 6 - 20m painted, I will make some pictures of the visibility before/after the paint job. This time it is not just a test, so it should be more thorough and even ;) .

Why do I paint my antennas ?

Well, I like to have as extensive an antenna system as possible, but a "normal" system of that sort would be extremely visible to neighbours. A lot of my antennas for HF, 6m and 4m have trees as background (not the sky), so all shiny objects, like aluminium antennas  become all too obvious, especially in bright (and low angle) sunlight.

The paint tested is "NATO Green", and I have also some brown and matte black paint that I intend to use sparingly, probably making some lighter and darker spots on the antennas, improving the camouflage effect.

2016-07-14

4m, 6m and 10m Combi Antenna.

In a Google search I just found an interesting antenna concept for simple antenna capable of running 4, 6 and 10m.

The antenna is essentially a 10m dipole (can be horizontal or vertical) fed by two lengths of twin-lead cable in series, (from the antenna feed point to the coax) 86cm 450ohm and 295cm 300ohm, fed directly (or via a 1:1 balun) into a 50ohm coax cable. The antenna in itself is 2 pieces of wire, each 258cm long (essentially a 10m dipole antenna). The antenna is a relative of the G5RV type, though not identical.

The gain on 10m is, of course 0dBd, on 6m the antenna probably has a gain of 1 - 1.5dBd, and on 4m it is an Extended double Zepp (2x5/8), and the expected gain is around 3dBd. Sounds to me like a neat compromise for a tri-band antenna.

New Antenna and Cable 6m/2m/70cm.

Yesterday I mounted my V-2000 vertical replacing the old Comet (GP-15, I think), and a new CFD400 cable.
The resonance frequencies :
- a bit low on 2m, but but clearly SWR below 1.4 in the whole band
- nice coverage of the whole 70cm band, less than 1.5 in the useable part of the band
- Decent coverage on 6m, the resonance was adjusted to 50.5 and the antenna is easily <2 in the high end, and <1.5 on essentially all frequencies I will use it for

This is now connected to my 70cm/2m FM rig, and tested on 6m FM. Everything works fine, and it is an improvement above my previous antenna system.

Future improvements of this antenna would be preamps near the antenna, though not in the mast, and possibly a power splitter at the outputs of the preamps, in order to use the antenna for reception on more receivers. The preamp system would then be after approx 8m cable and a triplexer. The preamps should be controlled per band, and that will take a while to design and construct, including some programming, sequencers, the preamps per se, and getting some useable coax relays.

Update : The cable is now connected to a MX62 diplexer, sending the 2m/70cm signals to the VHF/UHF rig, and the 6m signal to the IC7300.

This antenna, at the height it is, is better than the R6000 in its current position on the 6m band, so until the R6000 is raised to a higher position the V2000 will be my 6m antenna.

2016-07-07

4m and 6m Antennas

At the beginning of the sporadic E season I built a simple ground plane for 4 and 4m, just using a 6m fibre glass telescopic fishing pole and a bit of wire. The antenna works fairly well on 6 and less well on 4m, mostly due to its low height - the top of the antenna for 4m is only slightly over 5m above ground, so shaded by houses and trees.
The pole influenced the antenna considerably, and I was very happy to have my antenna analyzer when cutting it to the bands.
This antenna has worked about 40 countries on 6m, and 5 on 4m.
On 6m it operates a bit better than the R6000 at 3m height.

It was time for a better 4m antenna for local (FM) and a minimum amount of DX, mostly sporadic E. I decided to use a Sirio CX4 which is an end fed half wave antenna. The 10m half wave came down and the CX4 was raised to about 6m (feed point for the half wave about 7m. As expected this works much better than the low ground plane.
For working local stations in SSB, where most are running with horizontal antennas, I need to mount some kind of horizontal antenna myself. I am considering initially to male two dipoles or delta loops for operation in different directions, just to get it running. More elaborate antennas will have to come later.

Now, what to do about 6m ? I want to raise the feed point of the R-6000 to about 7.5m, and that should put the 6m part of the antenna a bit further from the trees around it, giving a better 6m (and 10m) range. On 6m some horizontal antenna is needed, and, again, I consider starting with 2 dipoles or delta loop antennas. A simple "V" shaped horizontal dipole could provide some degree of omnidirectional radiation, though.

For an omnidirectional antenna a "Squalo" (square halo), or a "Big Wheel" could work, or two "double quad"elements at 90 deg. could be fed in 90 deg phase difference, providing a modest gain.

I would like to generate some more gain on 4 and 6, and some kind of phased arrays for fixed favourite directions are in my thoughts. Older hams may be familiar with the "Lazy H" antenna which has a bi-directional gain of about 6dBd. This antenna can be fed with open line feeder and a tuner, making the same antenna suitable for both the 4 and 6m bands. There are other options, and they will be explored.

For now the 4m antenna is operational, and I am often QRV on 70.450MHz FM, and sometimes around 70.200 SSB or CW.