Monday, July 18, 2011

Retiring this call sign

Well, the call sign is a little over three years old. VK5FNET.

It has served me well, however I must move on, my new callsign has been allocated.

Sunday, June 26, 2011

Study for license upgrade nearly complete

I have been studying for the Standard license upgrade course with Paul Hoffman, VK5PH, for the last three months. 12 weeks on a Tuesday evening with a dozen other hopeful students.

Well the last class was last week and I have a few things I need to re-read. Given my results on the in class practice exams, Paul has suggested I actually sit the Advanced theory first instead of the Standard theory. On the Advanced practice exam I would just scrape a pass mark. Not confident enough just yet. Good news is I am pretty confident about getting 90+% for the Standard theory and the Regulations.

The exam in this coming weekend. So I have to make up my mind about which exam to sit. I would love to do the Advanced and be done with it.

I have a couple of topics that I am not confident yet, mainly Valves, transmission lines and antenna loading. I have four nights free this week, so I will read up and see how things go =)

The really hard part is choosing to let the ACMA/WIA give me the next available callsign or choose one of my own. $5 or $20 respectively. Decisions, decisions...


Big trouble in little Corolla

The little Corolla has been getting steadily worse in the starting on cold morning. Saturday it stopped working all together. Hey I can use a screwdriver and sand paper! This looks easy, the internets tells me this is a common problem with Corollas and is a twenty minute job. Famous last words!

So, after disassembling the solenoid on the starter motor of the car, including un-soldering the solenoid winding from the cap. I cleaned the main starter motor contacts. They were a mess, so I sanded them back and tried to clean all the black gunk off. I cleaned all the other conductors and reassembled. As you do...

Then bolted the starter motor back in the car, tried to start it. Nothing.


Fiddle around with key switch wiring, contacts, etc etc ... nothing. There was only 6 volts on the ignition key switch to the solenoid. Not sure if there is lots of lossy connections between the battery, switches etc. Bother.

Find battery is a bit low on the volts. Put the battery on to charge, went over to a friends place for diner. Got home, the battery seemed to be charged suitably. Went to bed.

Got up this morning, to ponder the issue of there not being enough volts on the ignition wire, scour the internet for more ideas. Walk to servo to find a relay and connectors, etc. They had nothing. Zip. Bother...

Go home, listen to the WIA broadcast and ponder other possible solutions.

After a couple of phone calls shuffling my calendar, I walk half an hour into town to find Sprint Auto to find these parts. Sprint Auto was closed. Was not liking my luck at this point. Walk to Repco. \o/ Its open! Speak to geezer about what my problem is and what I thought might be a suitable solution about not enough volts on the key switch. He suggested that it sounded reasonable, but I would be better off waiting until tomorrow to find an auto-electrician or get a reconditioned second hand one. I needed the car running today. Things to do. With a lighter wallet and a pocket full of parts I walked half an hour home.

Got home grabbed some lunch, had another look on the internets to see if I could find someone else with a similar problem or at least a circuit diagram and repair manual type information. At this point I knew there was something that I did that was amiss. Couldn't quite put my finger on it.

Build up a relay that is trigger by the ignition swith from the key, powering the solenoid from the battery direct to get more current through to pull the solenoid in. The solenoid wasn't moving, but the motor was turning. This was very, very wrong.

Realize that maybe the solenoid was actually dead, maybe a broken winding. Decided to pull the starter motor off the car and ponder some more. I couldn't actually find anything on the Bosch model at all. There were a lot of NipponDenso models that looked similar. At this point I started comparing any starter motor for the 4A motor I could find. At some point I noticed that the large contact studs on the back of the solenoid were wrong. The short stud was on the top, away from the motor and the long stud was on the bottom, closest to the motor and connected to the positive cable for the starter motor. Hang on a second...

So at about this point I looked at a service manual for an AE86, which is a different model, but gave me the most detail for an 1988 corolla I could find. The schematic on the AE86 go me thinking about why the motor was spinning without engaging the solenoid. You got it, I had put the thing in upside down and solder the wires in back to front in the circuit.

After another half an hour, I had assembled it the right way and put it back in the car.

Not expecting it to even move the solenoid, the car car started smoothly and ran! So I switched it off and added my ignition relay, and that started nicely too. So I tidied everything up and took the car for a lap around the block, to be sure.

Half hour job, eight hours later! At least its working properly now and we can now go do those things we need to do. =)


Monday, May 02, 2011

recycled steerable dipole

I rescued an old teevee antenna from Karl before he escaped the state. (he has gone to vk7 land).
it had a number of 'large' elements on it for VHF and lots of small elements on it for UHF. =D

I striped all the elements off the boom and started looking at useful arrangements using the longest ones. did some numbers and worked out that i could use the largest and third largest elements and reuse the 'egg' insulators for a reflector element, then wrap an inductor around the 'egg'.... =)

Did the measurements, rough numbers for the coil, should be good for the middle of 10 meters. \o/
Put it together, then spent the rest of the afternoon cutting firewood. consequently I ache all over! =/

So after the pot-belly stove is fired up and the dinner is on the boil, I test the antenna to see where in the 10 meter band it works ok.

So it fails as a dipole for 10 meters. Rather badly actually the SWR > 5:1 across the whole band =(
Not to be discouraged I tested it on 15 meters. Bingo! The SWR < 1.5:1 across most the band. \o/

So lesson for today, is my modeling/measuring concept is right out. However the consequence is that if I tinker with the coil I should be able to find a tap point suitable for 10 meters. A job for next weekend though.


I've added some images of the process and what the final center and loading coil looks like.
It is not particularly self supporting, as the final elements are much longer than the original teevee antenna.



Monday, April 18, 2011

Listening for Yuri's day ...

I was organised, got the ALICE pack all setup to record the commemorative transmission on the 12th and again on the 13th.

I listened for many passes ... Not a peep =(

Anyhow, found this today;

"The planned operation of ARISSat-1/RadioSkaf-V/KEDR on April
11 and April 12 from inside the International Space Station
as part of the commemoration of the 50th anniversary of Yuri
Gagarin's flight was not successful. No earth stations on
the ground reported hearing transmissions on the ARISSat-1
downlink(145.950 MHz for FM analog/145.920 MHz for digital).
The planned retransmission of the satellite's FM downlink
via the Kenwood TM-D700 transceiver --currently used for
ARISS contacts--was also not successful as no reports were
received of signals heard on 437.550 MHz. However, a
similar ARISSat-1 transmission test conducted in February
was successful, with 145.950 MHz signals being successfully
received by several ground stations. "

ANS-104 ANS Special Bulletin - ARISSat-1 Not Heard During Gagarin Commemoration

Thursday, March 03, 2011

Exciting developments in GNU Radio

The article; Exciting developments in GNU Radio, describes updates to the GNU Radio project.

I wonder if this can tie in to the SDRCube project that Erich VK5HSE has been tinkering with?

73, Kim

Wednesday, January 12, 2011

Land of Lisp

I have been getting into Lisp recently. Quicklisp has made the process a fair bit easier, so I took the plunge and ordered a copy of Land of Lisp.

What do I want to do with Lisp? Well the main reason is that I used to code in Lisp back at Uni. I would like to do some log processing and sensible matching against multiple rule sets. However I suppose the idea that Land of Lisp is learning Lisp through creating games was quite an attractive idea.