## The Vertical Dipole

| categories:

I plan for a while to try out another vertical concept, since I figured out, that my 6.5 Meter Vertikal having some trouble coming to its full performance because my Truck roof is definately not enough for Bands below 17 Meters.

The Question of the right radials on a multiband vertical is a good question, it should be $\frac{1}{4} \lambda$ most of the designs simply add verticals for each band to the design. You could also use an earth tuner to match your antenna to your vehicle, note to me: schedule some experiments with earth tuners on the sidecar radio outfit.

An other way is to look how dipoles are tuned and adapt it to a groundplane antenna. So you can use some radials with exactly the same length as the antenna, and than feed it with a balancer unit. I did it with my antenna, and it worked almost well, almost because the 1:1 voltage Balun I used maybe was not the best choice, but it worked anyway. The main problem I had with the groundplane design where the radials. 6.5 Meter to every direction means lots of extra space around my truck, I can't reduce length with couls because the coilsize debends on the frequency. And the only Idea I had for the mechanic of the radials was the use of tensioned wire.

So I need a design which is playing without radials! A vertical Dipole for example. With a feed in the middle. There is a vertical $\frac{1}{2} \lambda$ monoband design available in Rothammels Antenna book which feeds the antenna with koax cable right through the bottom dipole element. The design is basically the same as with a normal dipole exept that it is vertical and the feed is not coming from the side. So should be capeable of multiband work by adding some sort of Balun some sort of Tuning to the feed point.

This raises to questions: How to tune, and how to do the Mechanics. The Mechanics question was solved by ordering a Havy Duty 10 M GFK Mast at dx-wire.de. the mast costs about 70 € but alows rapid development of different antenna designs with much cheaper materials than the aluminium tubing, I used since then. I can now use old RG213 Coax cable or speaker cable as antenna element for example. I also ordered the portable 10m version from dx-wire which soon will improve my portable antenna situation soon.

The next problem to solve was the matching problem. I want something which I can control from the shack. It is possible to place a symetric autotuner at the feed point i decided against to make the feedpoint simpler and lighter. If you match in the schack you have higher losses on the Koax cable. The choice which death to die was finally made by the large collection of available Unsymetric autotuners, and the time i had available. I can still add some extra antenna tuning in the next project, when I know how the whole thing plays. Ham Radio is still an experimental Service, so what.

I build an antenna with two 3,65 m long elements. This length should work from 10-15 Meters. it is a little bit to short for 17-20 and 20 Meters. At 40 meters there is still a little less than $\frac{1}{4}\lambda$ left, but a single element is to short. On 80 Meters such an antenna will be some sort of wet towel, but still better (longer) than my other 80m solutions.

I decided to use RG213 cable for the upper element. The schielding radiates the waves the inner conductor is left unconnected. The case of the Feed is made of waste pipe and sealed cable feedthroughs.

The lower antenna element is a bit more tricky, I stripped 3.65 m copper schielding tube over the ecoflex feed cable and isolated it with shrinking tube:

The next part the (first) balun. A 1:1 Voltage balun. 8 Windings per Coil 50mm waste Pipe.

The whole antenna setup:

Now to the Problems did start:

I could match the Antenna only with a Manual MFJ T-Match not with the Autotuner I want to use.

• With 1:1 Voltage Balun Fail 40 Meter
• With 1:2 Voltage Balun Fail 15 and 80 Meter some bands not optimal
• With 1:5 Voltage Balun Fail on 80 Meter and some bands not optimal

Then I tried a Current Balun:

From 10-40 Meter best match, 80 Meter is not working. So I tried out to add the Coil of the manual L-Matchbox which I build 1.5 years ago. The SWR indicator is moving, so I need more inductivity. I killed an old CB-SWR Meter (I have lots of them) and found an old Ferrit ring in my shack, and made a coil. I build in a Switch that plugs in the 80m inductivity betwen the inner conductor from the Matchbox and the inner conductor to the antenna.
With that coil and the Matchbox SWR was almost good, so I added more windings and more and more until I had 2 ferrit rings full of cable and still the manual Matchbox in the system. I did't know the $\mu_r$ of the ferrit rings but from my calculations I expected something about 90 windings, to much for that ring. Which after several days of experimenting, leads to a more radical solution:

Match!!

Because ham radio is still experimental I did not add any shielding to that gigantic coil. 80 windings on 11cm waste tube, It seems to work, and it is disabled on the higher bands. I surely will soon find out how bad/good or however this setup performs. ;-)

## Chinese monkey escaped from box

| categories:

I thought about getting one of those chineese monkeys, for a while. Last thursday the cage from china was delivered, by a german monkey dealer.

I freed it from the cage, gave it new schoes, some oil, inspection and a speed sprocket!

It makes fun riding it. Those Bikes only weight 60 Kg. I did't test the fuel consumption, but the commercials say about 2.8 litres. So it is a good and easy city bike.

to the gallery...

## GS Broke down

| categories: ratbike

Also, a few weeks after that missdated post, my Suzuki Cylinder head broke down. It was ill on the left exhaust valve but now also the camshaft bearing is broken.

The valve cover was so rusty, i hat to grind away three screws.

## meanwhile, i was thinking about single cylindered engines

| categories:

The idea was to get around a frame mod. this time, but it was depressing, the ural frame i have left is to small for the E75.

I think I need another frame.

Gallery here...

## Speaky riser board

| categories:

I soldered the speaky raiser board for the 9 Band modules as I mentioned during an earlier post.

The following set of pictures may give you an Idea how I made it, and how it fits into the Tranceiver.

## Speaky 9 Band Extension

| categories:

Yesterday I did some work on my speaky. I soldered together all the remaining Band modules and put them on a raiser board which fits into the Box.

Seriously I do not know how this will work on the HF side, mechaninally this is not a problem because the Box is much bigger than needed due to the frequency counter.

You need to do some cleanups to bring all the modules in.

The plug for the freq dialer must be grinded down a little bit. The whole Mainboard must go 4 mm lower what you can do by grinding $45^\circ$ angles into the metal cubes what enables you to leave the spacers away.

Test will come in a few weeks.

## Found pictures of my sidecar build...

| categories:

I just found some Pictures from the build of my sidecar boat...

Gallery here...

## Got another engine

| categories:

I got another engine. A friend gave it as a gift.

• Hatz E75
• 350cc
• 6 ps

There is also an old Ural frame available together with some parts for a cool bike! Estimated fuel consumption should be 1-1.5 Liters. I hope.

The engine is perfectly healthy even if it was lying around for several years.

## Just found MathJax

| categories:

during some web research I found which is basically a javascript which can format LaTeX Formulas on your website.

Let's test:

$$U=\sqrt{P \cdot R}$$

all right.

## Speaky Progress....

| categories:

The Speaky board is soldered and ready for testing.

## Working on my Speaky goes on...

| categories:

Unfortunately the VCO is still not working as it should be :-(

## TeXCalc a Calculator for uncertainties and LaTeX

| categories:

Hi there,

during the last year I developed a command line calculator in python which can calculate numbers with uncertainties.

The Tool is also capeable to interperate with LaTeX doing python calculations within a

\begin{calc}...\end{calc}

environment. Finally you can set your results rounded to two significant digits directly into your LaTeX formulas by using

$\val{foo}}\approx \val[1]{bar}$

You can find out more on the project website: http://www.nawi.at/~zem/texcalc

## GIT is cool

| categories:

Most of the time. ;-)
you can easily forward a remote git repo to github by using a send hook:

(
PATH=\$PATH:/usr/local/bin
LOG=/dev/null
unset GIT_DIR
cd /home/zem/devlocal/phunivie
git pull origin master
git push -u github master
)

The hook is placed in a bare repository which is then cloned to a local copy on the server which is then pushed to github
of course you need to add a github origin, first...
git remote add github git@github.com:zem/texcalc.git

## Rat&Survival + BigKnock 2012

| categories:

This is the gallery of my rideout to the Rat&Survival Bike Show and the Big Knock Dieselbike Ralley 2012. Have fun!
Watch Gallery!

## first kubota test run

| categories:

Here a video of the first testrun of my Kubota D950

Unfortunately it burns oil on two cylinders, the water pump does not work and the crankshaft bearing is gone after the run. So it will take a few weeks more to get my second diesel bike on the road.

## Easter horrorshow

| categories:

The first set of pictures shows one of the exclusive Ural dry-enddrives in good shape. Those drives are dry to prevent oil from dripping on the street. Even if you fill in Oil to them, it will last for 20000 km until the bolts of the cover getting lose and the oil will leak out. You can drive another 10000 km when that happens.

The next set shows another end drive which has some serious cracks in its cover, so it ist useless until I figured out a way to get that fixed.

After I found some slightly useable parts I failed to mount a new enddrive ratio, the cover is not closing, I will write more about that when I know whats going on with that transmission:

Finally on the investigation of the Kubota engine I want to show you a short video of the Injection pump:

## coming soon... the vertical antenna project

| categories:

One of my current projects is to build a proper antenna system for HF amateur radio bands on the top of my lorry...

After it is almost finished I must admit that this was more complex than I thought. So I will soon write down my Experiences into 3 threads:

• vertical antenna for 10m - 40m
• antenna tuner up to 100w
• DDRR Loop for 80m - 160m

I will also show you what can go wrong, because I constructed almost everything twice.

## Final-drive issues

| categories:

Last weekend I traveled to the 20. Ratbike Wintertreffen near Ulm. On the campsite I discovered that the final-drive was not transmitting full power to the wheel anymore...

Obviously there are some pieces not in their place. Fortunately they are not important, except if you want to drive.

| categories:

Update: This article takes the Mark kid's do not try this at home because there is a proper solution, from the Suzuki Workshop handbook, which I do not have! The solution is to build out the camshaft and the tappets and grind down the valve shaft.

This weekend I made a huge Inspection on my GS500E when I discovered that the Valve playing on my left exhaust valve was gone. Unfortunately this was the one with the 215er Shim which is the smallest available.

I think the cylinder head is dieing, since the valve is digging deeper and deeper into it. Which is the cause of a lack of
service a few years ago. But why not grind those shims down, drive another 20000 km?

This is how I did it. First I drilled a 2 mm hole with a forstner drill into a piece of wood:

Then I angle grinded one side of the shim down. Being careful not to overheat the shim. When I had the right distance, I finisched it with a sander. I put the grinded and sanded side to the bottom, so the cam can pusch on the original side.

I don't know how long this will last, but I hope it is better than doing nothing until the engine breaks down.

| categories:

Next Page »