AE EP#34 Heathkit IG-102 RF-Signal Generator

Hi Folks,
After more than a month of video-making abstinence I finally managed to make another one.
It’s about the classic Heathkit IG-102 signal generator. 2 Tubes, the 12AT7 and the 6AN8 make up 4 oscillators (3x RF, 1x internal modulation). Some little hack at the end…

if you need some manuals I probably can help you. I can’t put up any manuals ’cause Heathkit was a little cranky about that sort of thing – so until the situation is clear, just ask.

AE EP#29 Oscilloscope Project: The heat is on!

Hi guys!

I just made up some working test setup for the homebrew oscilloscope project and the screen came to life for the first time:

Here is my setup:

By the way is the 3KP1 / DG 7-113 with the green p1 phosphor. If you ever come across the white phosphor (3kp4) you found some nice piece of rareness. The P4 version was used in the Pilot TV-37, one of the first portable TV-sets. Check out David and Marlene McClellans blog about restoring one! Also check out some video of it here.

AE EP#22 Electron Tubes Basics & Example Amplifier Project

In this video I quickly cover the electron tubes basics and show a little tube amp project, that uses the 1T4 (DF91). The 1T4 is a low voltage tube that can be operated from 45 (it actually works with 12V too) up to 90 VDC and a heater with only 1,5 V. It is also very cheap and can be as NOS for about 0,5 to 1€.

To make more bang I just put two tubes in parallel. In my configuration the whole set-up makes about 150 mW of sound power.

Find the circuit I followed at: http://www.hobby-bastelecke.de/projekte/roehren_kopfhoererverstaerker.htm (german)

AE EP#21 Minerva Minola 3 Teardown

This is just a short teardown of the classic austria-made Minerva Minola 3 radio from 1967/8.

Here the promised pics:

Full front view of the Minola 3 in all its glory.

 

The two Varicaps:
Up: the gear to the varicap on the pcb.
Below: LW and MW system.

 

External speaker connector on the left, back in the middle the impedance transformer for the speaker and on the right mains transformer with fuse holder.

 

Front-panel switches and pcb from below.

 

The main board mounted on the chassis with tubes. The paper in the middle acts as a diffusor for the front panels back-light.

 

I’ll post an update if I ever get the schematic to fix the Volume pot.
Find out more at: http://www.radiomuseum.org/r/minerva_minola_3_673.html
More about Minerva at: http://www.minervaradio.com/
Nice holidays to you all!

AE EP#7 Heathkit V-7A VTVM Voltmeter

This is a little vid about the classic Heathkit V-7A, predecessor of the Heathkit models IM-11 and IM-18. They all had an almost identical Circuit and were manufactured from the 50tier until the early 80ties. I am doing some little repairs on faults that came from a leaky batter and show how to measure with it.

some more info here: www.glowbug.nl/valve/Heath-V-7A.html and on Jogis Röhrenbude you can find the manual: http://www.jogis-roehrenbude.de

Tube Power Supply #1

So I’m working on this tube power supply and I found a way to get 300V~ by connecting a second transformer in reverse – the problem with this solution however is that I only got 2 power-terminals on it. So the road of doing it that way is closed.
Can I use 4 EY88 TV Rectifier Tubes (500 mA@5 kV) as a full-bridge-rectifier?

what the Hell – I’ll just throw in some silicon