gerard – Geronimo/370

Retro Z80 computer (11) – (dis)Assembler

Posted on2022-12-06Leave a comment

At first, on my retro Z80 (RC2014) computer, I was using the assembler that came with CP/M, named ASM. Later on, looking for the Z80 block transfer instructions and not able to find them, I found out that it is an 8080 assembler. (hey, it’s been a long time since… Read the rest

Last connections made (QSO’s)

Posted on2022-05-262022-11-19

Below you can see the last 15 QSO’s I made, as logged on QRZ.com. A yellow star means the contact has been confirmed by the other station, a little grey circle means confirmation has been requested. Normally I ask for confirmation with each contact; absence of a yellow star or… Read the rest

Common mode filters

Posted on2022-05-212022-05-214 Comments

This afternoon, I will be taking my Novice exam. So in preparation of being allowed to transmit, I decided to create a barrier for HF. I did so by making a number of loops (7) in the coax cables, just above the ceiling. These loops act as coils and they… Read the rest

My bike

Posted on2022-05-092022-05-09

Recently, I traded in my BMW R1200 GS for another bike, the K1600 GTL. See pictures below. It is a very, very comfortable motorcycle. It has a lot of power as well, since it has a six cylinder engine with 1650 cc, about 160 Horse Power and a max torque… Read the rest

FT8 data from the noise

Posted on2022-04-302022-04-30

It’s truly amazing what can be accomplished with digital modes like FT8… Noise Have a look at this waterfall, it looks like the 10 meter band is dead, it only shows a few very faint signals in the 10 meter band: Despite the weak signals, the FT8 program I use,… Read the rest

Fixing old Nixie Clock (3)

Posted on2022-04-282022-04-28

Capacitor replaced The replacement of the power supply capacitor with a new one cleaned up the pulses nicely. The clock is running properly again for about two days now.… Read the rest

Fixing old Nixie Clock (2)

Posted on2022-04-232022-04-233 Comments

Remember that old Nixie Clock? For a while it ran properly, but now it skips time again at random intervals. So I got that big capacitor out that I suspected right away, because it has been in there for over 40 years. And unlike me, these things do not age… Read the rest

NanoVNA measuring antennas

Posted on2022-04-222022-04-23

Yesterday I received my NanoVNA (small Vector Network Analyzer). Among other things we can measure the return loss in antennas (or the Voltage Standing Wave Ratio or VSWR for short). Return loss or VSWR VSWR is the ratio between the energy that goes to into the transmission line TO the… Read the rest

Coax switches, measuring

Posted on2022-04-172022-04-17

An interesting video by W2AEW about measuring on coax switches to make sure one can leave a receiver connected when transmitting over another connection of the same switch:… Read the rest

SDR control iPad app for ICOM sets

Posted on2022-04-162022-04-16

Today I came across a very nice app with which one can control Icom transceivers. It is available in the App Store and it’s called SDR-Control for Icom. It works for LAN connected radio’s, so no cables needed, you can operate your set via Wifi. Icom’s IC-705, IC-7610 and IC-9700… Read the rest

Fixing old Nixie Clock (1)

Posted on2022-04-102022-11-22

Father’s clock My father built a Nixie clock in ‘ye olden days‘, over forty years ago… It was a relatively simple design compared to what we build nowadays. Design and simplified workings The clock derives it’s clock-pulses from the mains power, 50 Hz here in the Netherlands Dividing it by… Read the rest

Switches connected

Posted on2022-03-182022-03-18

I have made a little diagram showing how my antenna’s and rigs are connected. So I can switch my 2mtr/70cm antenna to three sets, and the HyEndFed for 10,20 and 40 mtr to two sets. Numbers in the arrows indicate switch settings. See below: Antennas, switches and sets… Read the rest

Antenna switches

Posted on2022-03-052022-03-054 Comments

Yesterday I ordered some antenna switches (from HAMshop, where else?) and today they came in. One is for HF and the other for VHF/UHF and higher. See pictures below. Also, I have a question for fellow HAM’s, please have a look at the bottom of this post. HF switch (PL… Read the rest

Experimenting transistor amplifiers (3)

Posted on2022-02-182022-02-25

The circuit for today Today I take it up a notch, by making a two transistor amplifier. This time I use the circuit diagram at the right (published on Jos Verstraten’s website). As a convenient touch, measuring points are given in the diagram, indicating the expected Voltages. Building the circuit… Read the rest

Experimenting transistor amplifiers (2)

Posted on2022-02-182022-02-18

Follow-up As a short follow-up for the previous post I will show you what is the result of using the right value for R4 in the schematic, which I did wrong in the previous post. I accidentally used a 47k resistor in the collector line of the transistor where it… Read the rest