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Old 27th Oct 2010, 11:52 am   #21
mhennessy
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Default Re: building a tube ghetto blaster

Would look really nice covered in Rexine rather than paint

Mark
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Old 14th Dec 2010, 6:33 pm   #22
6AL5W-Martin
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Default Re: building a tube ghetto blaster

hello friends,

it`s a long time job to build this radio, but with a lot of fun

to be continued..
greetings
Martin
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Last edited by 6AL5W-Martin; 14th Dec 2010 at 6:41 pm.
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Old 14th Dec 2010, 8:15 pm   #23
6AL5W-Martin
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Default Re: building a tube ghetto blaster

front...
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Old 29th Dec 2010, 10:02 am   #24
6AL5W-Martin
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Default Re: building a tube ghetto blaster

hello friends,

I have made mechanical parts of tuning including transmission for the scale.
The pertinax roll on the Capacitor is the one where is to fix the indicator,
this will go around the eye tube, in the scale.

transmission plan:

Capacitor goes 3 3/4 turns,
Scale = 70 degrees = 0,2 turns.
Small rolls 1 + 3, same size, set to 12mm ( 1/2 ")
Big Rolls, same size, means 2 identical transmissions in line.
The transmission of each of the both is 4,3 : 1
So the big rolls are 12 x 4,3 = 51,6mm (~ 2")

3,7 / 4,3 = 0,872 -> 0,872 / 4,3 = 0,202 turns, passed.

1 fixed on Capacitor
2+3 = 1 part
4 sliding on Capacitor


greetings
Martin
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Old 3rd Jan 2011, 3:30 pm   #25
6AL5W-Martin
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Default Re: building a tube ghetto blaster

hello friends,

I have build my first homebrew fm tuner.
Now I will insert it in the radio and hope to get it running.

greetings, and a happy new year.
Martin
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Old 3rd Jan 2011, 3:40 pm   #26
TuningIndicator
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Default Re: building a tube ghetto blaster

Scratch-building an FM tuner is no mean feat; is it your own design, or did you copy something?
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Old 3rd Jan 2011, 4:08 pm   #27
6AL5W-Martin
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Default Re: building a tube ghetto blaster

hello,

it`s own design, yes. double EC92, and Im not sure if this will do,
may be I have to change something.

Martin
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Old 4th Jan 2011, 6:53 am   #28
6AL5W-Martin
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Default Re: building a tube ghetto blaster

hello friends,

this is the design of my fm tuner.
warning: it`s experimental and can include mistakes, I`m testing.

2 tubes EC92

greetings
Martin
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Old 4th Jan 2011, 8:33 am   #29
6AL5W-Martin
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Default Re: building a tube ghetto blaster

edit,

there is a mistake in the plan:
the 20 pF of feedback is connected to the Anode of the tube.
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Old 4th Jan 2011, 12:24 pm   #30
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Thumbs up Re: building a tube ghetto blaster

Hi Martin your project is very interesting to me.
Back in 1995 in Dalian NE China whilst working for the Traffic Police they had a Ghetto blaster style Radio Cassette in the workshop. It had LED bar style output meter and all the usual refinements including a carrying handle and expanded metal covered speakers with a tweeters in the centre. A moulded plastic case looked like any other of its type, so far typical 90's Radio Cassette but the Amplifiers were valved. They looked like EL84's and ECC83's as seen through the ventilation slots. It was mains only and even the local engineers found this a curiosity, but it had been built that way. I did try to negotiate its purchase but the local guys all liked it too much to part with it!.
The Radio and the Cassette were typical of the time and solid state. I wonder if its still there? Mike T
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Old 6th Jan 2011, 4:46 pm   #31
G8HQP Dave
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Default Re: building a tube ghetto blaster

The EC92 RF stage will need its grid to be tightly decoupled to ground, otherwise it will at best have no gain and at worst will oscillate. The cathode will have low impedance so the input circuit may need to be series tuned, not parallel as you have it.
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Old 27th Jan 2011, 1:56 pm   #32
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Default Re: building a tube ghetto blaster

Interesting project, in fact it looks tidier than some commercial units that I have had the mis fortune to work on.
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Old 11th Feb 2011, 4:07 pm   #33
6AL5W-Martin
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Default Re: building a tube ghetto blaster

hello friends,

yes, the radio is good for a long time, mostly learning
My fm tuner was working, but a low sensitivity, so I have learned again something and start to build another one, using 6ES8 as cascode , EC92 as oscillator without mixing, and a 6AK5w as Mixer/first IF. This looks much better, but it like to have a very shieldet box.. a lot of work and fun

Also i continued to build the case, upside metal cover with little cooling house for the hot audio stage, also for buttons (right side) and a plug for MP3 Player..
I have to make a black painted wood cover with a rectangle whole for the little cooling house.

greetings
Martin
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Old 24th Jul 2015, 12:01 am   #34
sexton_mallard
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Default Re: building a tube ghetto blaster

I just strayed onto this thread and have to find out - have you finished this project? I love projects like this and admire your effort so far
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