gerard – Page 2 – Geronimo/370

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

Experimenting transistor amplifiers (1)

Posted on2022-02-132022-02-181 Comment

Today I thought I’d play around and build a simple amplifier, just for fun. I started out searching for circuit diagrams for “one transistor amplifier BC337“, just because I have a couple of those BC337’s laying around. I found a schematic that you can see to the right: It is… Read the rest

Retro Z80 computer (10) – Pi-Terminal

Posted on2022-01-262022-01-26

I got one of my raspberry Pi’s out of storage and made it to be a terminal for the Z80:… Read the rest

Retro Z80 computer (9) – BLINKENLIGHTS

Posted on2022-01-212022-01-21

A small project today. I added ‘BLINKENLIGHTS’ to my Z80. This term stems from an old sign that used to hang in computer rooms: ACHTUNG!ALLES TURISTEN UND NONTEKNISCHEN LOOKENSPEEPERS!DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKEN.IST NICHT… Read the rest

Retro Z80 computer (8) – IDE disk

Posted on2022-01-162022-01-19

Where I originally thought that I could connect a floppy to my IDE card (silly me) I seem to have forgotten that IDE is a Hard Disk connection… Oh well, my brother still had an old Hard Disk laying around that he was prepared to part with. Got it today… Read the rest

Origin of radio numeric codes

Posted on2021-12-272021-12-27

Searching for the origin of the ‘73’ code at the end of a message, meaning something like ‘kind regards’, I found the following. Glen Zook, K9STH, posted this to the Heathkit mailing list: Many amateurs already know that “73” is from what is known as the “Phillips Code”, a series… Read the rest

Christmas in the shack

Posted on2021-12-272021-12-27

Do you guys also get the Christmas feeling and make it visible in your shack / workshop? What do you think, is an image like this recognizable? I do… Xmas shack… Read the rest

Retro Z80 computer (7) – Almost complete

Posted on2021-12-212021-12-22

Here’s a picture of the progress so far. It now also includes a RTC (Real Time Clock) module. What you might also notice is the flat cable I attached between the serial card and the serial to USB connector. That connector, as you can see in previous posts, was attached… Read the rest

Retro Z80 computer (6) – It works!

Posted on2021-12-16

I am one happy maker, I got my Z80 computer working right after building. All went well! The first lines of output are the boot screen: CP/M And of course I wanted to see CP/M running: Z80 Basic And after that, on to Z80 Basic version4.7b:… Read the rest

Retro Z80 computer (5) – Dual Clock Module

Posted on2021-12-162021-12-16

Without an internal clock nothing happens inside a computer. It’s the clock that makes the computer ‘tick’, chew away instructions that is. Last I assembled this module; it contains two clocks. Both clock signals are being put on the bus on the Backplane board. It’s starting to look like something…… Read the rest

Retro Z80 computer (4) – Dual Serial Module

Posted on2021-12-15

And another one bites the dust… The Dual Serial SIO/2 module has been assembled and soldered. With this one I had to search for the value of the resistors, because the info was not in the documentation. Eventually I ended up looking at the pictures of an assembled one online… Read the rest

Retro Z80 computer (3) – Memory module

Posted on2021-12-152021-12-15

And the memory module for my Z80 computer is finished. It contains 512K of ROM and 512K of RAM memory.… Read the rest

Retro Z80 computer (2) – backplane and CPU board

Posted on2021-12-152021-12-15

Yesterday evening I assembled and soldered the backplane board and the CPU board. Around 600 solder joints…… Read the rest