6Ж5Б-В (6J5B-V) Audio amplifier

Do not expect to have here the latest greatest audio tube/valve amplifier.

Having said that, it works for me and still give a reasonable audio output, understand by reasonable; it's audible but not big volume, you can keep comfortable the speaker 10cm from you ear. Let's said this is the amplifier you need in case you run out of any other device that can give you audio amplification.

Some photos and diagram bellow.

The glow:

..violet color on the heather is due to camera, in reality is more on the orange/yellow side.

The testing board

The schematic

 ..this worked for me, for sure there could be a lot of improvement but I just wanted to try and prove the concept. The "audio output transformer" is just a 230/9V power supply one, I tested with a 230/15 and with one with multi taps and all work but would be preferable to use a real audio one.
This also works if you remove the left side o the circuit and inject audio directly on pin 7 of the rightmost tube (with the audio transformer), at the expense of lower output.




Audio sample listening to 10.100Mhz weather station with a lot of fade.

The audio from the capture is not the greatest, a little better in real but still on the low side, I'm sure with a real audio output transformer, a higher supply voltage and some optimization would be a reasonable amplifier, but again you have other specific tubes and designs to make it better. 


Have fun!

World Amateur Radio Day - 6Ж5Б-В (6J5B-V) Oscilator

Yes, it is today at least for those interested in calendar advents!

I suspect that for the majority it will be all days, weekends or occasionally, it does not matter as long as the spirit is alive. I also does not matter if your interest is DX, QSL collection, home-brew, 500m or light-wave.

For me since it's mostly building and learning RF electronics in the process, here's today "project":

I had some Russian 6Ж5Б-В (6J5B-V ) miniature tubes laying around for long time, so decided to build something with them, or at least try.
I think they were chosen just for fun and to make combined postage in another components order.

Components values are not optimal since I was building and doing guess work at the same time trying different values. Keep in mind I'm no expert in tube technology (nor transistor for that matter just to be clear).  That said, do not replicate for any other purpose than fun.

The tube/valve 6Ж5Б-В (6J5B-V ):



The warm glow, always nice to see:

and the outcome:

No output filter but again the RFC used are on the low side values:

Final schematic:

(add: latter changed the top 200pF capacitor for a 20PF)

To be honest I was not expecting it to work since the anode voltage was too low and I haven't a higher voltage power supply.

Have a great day!

IN-9 (ИН-9) BARGRAPH NIXIE TUBES

...More tubes for the collection...or to make a VU meter when I have time.

Needed two, bought 4, just in case, luckily only one failed testing.

Testing another:

and the last one:

...looks around 10 "dashes" in difference between these two tubes, in any case it's not a measuring instrument and can be corrected on the control circuit. Also no precision supply used.... only 84 Vac from 230 to 12 --- 12 to 115-0-115 transformer arrangement (using only one 115v output):

Have a nice week!

Magic eye 6E2 tube/valve kit

Since I really like tubes/valves, bulb's, crt's, led's and similar light/electron emitting devices and looking for sometime to experiment with magic eyes, finally spotted one in kit form and within budged! After a month it arrived and costed less than 6 Eur, shipping included...

It arrived well packed along with the local bank publicity... I suppose...

The tube was a little dirty on the glass, my guess, it was made to be cheap and not to be beautiful like we see on some other tubes.

Connected the wires and started testing the heather, since this, besides the glass envelope, is the most fragile part...it was in good shape and didn't burned during power on! So far so good!

Now the plates power under normal light conditions, it worked! First time!

All the glory under low illumination:

Power supply using a 230 to 12 and 12 to 230-0-230 transformers as isolation, I had my share of electric shocks so I like to avoid them whenever possible:

A simple 7805 is providing the heater voltage.

And the schematic:

I didn't tried yet to bias with low voltage on the diode to see if would be simple to transform the circuit in a s-meter indicator from an agc voltage...


Have a nice week!

ECC82 Downconverter

I bough a spare ECC82 valve when I built the ECC82 regen receiver, already tried a valve VFO (worked), now decided to tryout a valve down converter as a first test to a tube direct conversion receiver.



Basically one half of the ECC82 is running as vfo then there's a single balanced mixer and will be an audio amplifier using the other half of the ECC82.
Interesting thing is that this circuit worked first time, I even forget to count the turns in the mixer core, the rfc was the first coil I found from an old PSU and the mixer output termination was the first small cap I found...
Signal out is not much but hell what do you expect from a lousy mixer made from a binocular core and 2 diodes and 4m of cable laying in the floor working as antenna...




The oscillator was running at 6.7Mhz and I was listening on 365Khz so one of the received frequencies was 7.067Mhz... I promise a schematic soon.

Add: here is the schematic used:

Tube/Valve receiver... the schematic

..And the finished product...


..Sort of, there are still somethings to improve like putting a volume pot and antenna coupling. I didn't found yet the optimal antenna setting so will improve it in the future.
The schematic used:
My valve/tube is the ECC82 which is an European version of the American 12AU7

Reference articles from here and here

ECC82 (12AU7) 12V VFO

Now that I de-freezed, on to work:
Found a nice article on a 12AU7(ECC82) vfo here, decided to try out the circuit using less lethal voltages (I had my fair share of electric shocks if you know what I mean).

Here's the prototype:

...admire the beautifull wiring work...and circuit...you can find a clear one in the article link provided above.



It works! The only hard part is to make the a coil for it. Mine was done with the cientific methot of trial and error...oscilates around 800-1200khz but I intend to make one for 5-5.5Mhz.

This was just a proof of concept but working with 12V supply and no buffer it can deliver about 0dBm measured from my NCY (Not Calibrated Yet) AD8307 power meter.

It takes a little to get into oscillation due to valve warming as you can see in the video:



Having time and a nice box to put it, looks like a nice little external vfo for one of my vintage HF radios....one of this days....