Vacuum tubes tester

Growing family of my Hallicrafters devices requires some maintenance and restoration work. The heart of every receiver or transmitter are the vacuum tubes. They are very old and usually in unknown state. Checking them is possible either by checking that radio works at all or measuring their parameters with some special devices. 

This is where tube tester comes to the stage. It applies the filament power to make the cathode hot and voltages to the plate and grids. With specified values of these voltages the specific current should flow through the tube. If is according to specification then most probably tube is okay, otherwise needs to be replaced. 

For the filament power I used ready module of the power supply. It allows to set the voltage and current limit so specific values so it is possible to "wake up" old tubes with lower filament power at the begining. According to one of my friends the filament heater can be sometimes damaged if is not used for several years and the full voltage is applied. 

For the plate and grids I used ready tube tester module that I got from eBay. It allows to set plate voltage up to 500V, set Grid 1 & 2 voltage and measure the plate current. The measurement is done in short impulses only what prevents damage of the tube in case od wrong wiring or incorretly set parameters. 

I have tested some tubes residing in the shelf. The values were exactly as expected from the specification.

My first SSTV QSO

Many many years ago I was living in small town in Poland (Deblin). There were no amateur radio enthusiasts there so all my knowledge about this hobby I was finding in books and newspaper (for younger readers - no, there was no internet, youtube and wikipedia in that time).
I was subscribing a magazine related to amateur radio - "Radioelektronik".

One day I found an article "Odbiorczy przemiennik SSTV" (something like "Device for receiving SSTV". That was the first time, when I heard about SSTV mode. In that time transmitting pictures over radio sounded like supreman technology :)

Of course I started planning to build the device but I was on the level of single transistor receivers and the device built on nearly 40 IC(s) was far above my capabilities. In that time even finding all the necessary parts would be miracle...

But SSTV was always somewhere in my mind and I always planned that some day...
This some day is actually today :)

Some time ago I started to dig into youtube videos and articles related to SSTV. Finally some day there was a test of sending SSTV picture from laptop to mobile phone (over the sound only, no radio).

In old times there was one standard - the pictures were B/W and sending the picture took 8 seconds. Now there are various standards (not sure how to decide which should be used).

Plan for today was rather different - make some CW QSO from the mobile radio shack.

But conditions were ugly and managed only a few contacts - so decided to make a quick try...
Using the IC-7300 connected to laptop I tried to call some station using MMSSTV.

And finally ...tadaaaammmm:

That was my very first QSO on SSTV!! Some say that 34 years after the initial plan. Better late than not at all :)

Unfortunately I had only prepared a picture with his/mine callsign and second with just "73".

So dear Michael (EA1IYK), sorry that our QSO was rather short but I will send you my QSL and many thanks for that nice QSO and next time I will try to be better prepared :) 73!!

I was using the templates available in MMSSTV and only pictures I found somewhere in my PC.
Now working on extending these templates.

So see you some day on SSTV :)