Am Radio kit from China

Am Radio kit from China

Cheap Chinese Radio Kit

As a radio enthusiast from way, back I thought that it might be fun to build a radio from a kit.

A quick search of eBay turned up a simple six transistor kit for less than $10.

I was interested in a kit that was as close to the radio’s we had in the 1960’s which would leave out anything with integrated circuits.

Ordering the kit it was about 3 weeks  before it arrived and another 2 months before I opened it.

 

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Radio kit from China
Not wild about the color of the case nor the front plate, but this is a kit, not a work of art; right?

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notice the 2 transistor places marked v4

The board looks pretty straight forward.

Problem 1… the instruction are all in Mandarin.

T2, T3 and T4 Are not interchangeable.

 

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Parts list for AM Radio
Those character by the purple blotch are the designations of which are which.

On another part of the document is a chart for the resisitor color code.  Since I know what it is I can work it backwards and figure out what the colors should be.

 

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There you go…the primer as it were. BBROYGBVGW 
Now working this backward…The IF cans were identified.

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T5 is the audio output transformer and it too has a key.  Notice the white dot on the board and the slightly raised up bump on the housing of the transformer.

The rest of this was simply to populate the board correctly and see if you guessed right.

 

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board before final parts installation.
I noticed on the circuit board that there were traces that were not completed for some reason.  If I could read Mandarin I am guessing that possibly those are stages at which you could do tests before completing the entire circuit.

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Notice the C and the D… There is also an A and a B which are not completed either.

 

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Over to the left of the board you can see two of the incomplete circuit paths.

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This is why the kit is so inexpensive.
If you look carefully at the parts layout you will notice that V4 and V5 should really be V5 and V 6 as there are two V4’s wich in our nomenclature would be Q4,5 and 6.

So not only are the instructions worthless to those who cannot interpret Mandarine the printing is flawed.

 

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Schematic showing amplifier. 
My review and guess of this “kit” is that someone bought a bunch of them because they were dirt cheap as the printing was flawed.

The kit does not use a detector diode which causes it to lack sensitivity.  My guess is that they are using the driver Transistor as part of the detector as well.

Since these are silicon transistors and not germanium that too hinders the performance as a detector.

Once built you must insert a 455Khz signal with the variable capacitor open and tune the black If can for maximum sound output.

Using a non-metallic tuning tool you can then tune for your radio stations.  The two adjustments on the back of the variable cap work in conjunction with the oscillator and the last IF can to set the stations on the dial accordingly.

Even though this kit was cheap, unless you have some pretty good radio savvy, I would take a pass.

As an FYI the speaker is very tinny sounding.

I took a short video of it working but, the video type is not compliant with WordPress.  Sorry about that.

-Best

(c) All rights Reserved 2016

 

 

 

 

 

 

 

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