I sprang for a little Chinese radio kit on ebay. Total cost $13.49 delivered and it arrived in 10 days.
I started assembling it today. Little tiny parts and one SMD chip. Went pretty well. The components ARE printed on the other side of the board.
Since there are no English instructions one is left to guess the mechanical aspects of things like the battery terminals, dial, etc. I'm pretty sure this as a kit made for students and its pretty easy to figure out. I hope to finish it tomorrow.
Hey, it worked first time! Not much of a radio, though. My nearby AM swamps the BCB but I hear others underneath - like a crystal radio! I'll have to try again after hours when they drop to 1kw.
FM isn't as bad as I expected. Doesn't want to line up well with the dial but pulls in gobs of stations which is unusual for a portable set here. I think the FM section of the tuning cap may be a bit dodgy.
And the little poly speaker is hard on the ears to say the least - haha.
If anyone else decides to build one of these for entertainment I have photos now of the mechanical aspects that can be a bit confusing to figure out from scratch. Battery holders, dial assembly, etc.
Do you have a link to it on ebay?
I've seen them from other sellers but this is the one I bought from. He seems to be the cheapest.
I have been looking for a cheep kit to build for fun.
Hey, it worked first time! Not much of a radio, though. My nearby AM swamps the BCB but I hear others underneath - like a crystal radio!
Almost sounds like a TRF circuit. Can you post the print?
Here is the one in the eBay add.
Yup, no discrete IF stages.
I posted a thread a year or so ago, I think in home brew, about a receiver I made using one of these.
I tried it after WIVV drops power. Still no go. Way down away from 1370 it seems sensitive enough but I'd have to say that this radio cannot be used within a few miles of an AM transmiitter. I'll take it out fishing on Sunday and see how it does a few miles away.
There is also an old-school AM radio kit with IF transformers, interstage and output transformers like the early 1960's. I haven't bought it, as the instructions are also in Chinese. It might be more useful as a source of parts to fix other collectible radios. They call it a "Summer Teaching Kit"
That's not a bad deal, Don. I see its got free shipping as well. I'm tempted to check it out.
I took mine out to our fishing spot this morning. Its 8-10 miles from the local station. The radio performed fine out there.
So I sprang for the one in the aliexpress link. I had my reservations since the whole aliexpress operation seemed to be that of an amateurish reseller operation. I didn't receive any paper work or schematic with the kit and it wasn't well packaged. I have whined to them so we'll see what happens.
In searching for X-291 schematic I ran across this site also regurgitated by aliexpress. Not hardly a confidence builder!
If I ever do receive some documentation I'll post it on my website. But for the meantime I'd say stay away from aliexpress.
This is the China conundrum that we often consider but I've never had problems with Chinese sellers. Until now. Bad mark for all of them.
ling yuan: I AM SORRY . IT HAVE NO SCHEMATIC .
Scratch aliexpress as a reliable source.
So you bought an 8 Transistor AM radio, in which you are the one stuffing the board instead of a factory worker.
What was your reason for buying it?
Interestingly, shortly after I whined a schematic appeared on the ad. Not enough to do anything with, though.
EDIT: Found a good readable 2000+ pixel schematic elsewhere on the interwebs. We'll see how it goes.
Managed to get it built and it plays pretty well. There's a number of different issues without documentation like having different numbers on the transistors provided and no specificity in the IF xfmrs. That took some research and guesswork. The split antenna coil configuration had me flummoxed for a while until I tried to put my guess into the case. Now I see why they split it. It will only fit one way. Oh, and the on/off switch on the volume control had sprung so that needed to be fixed.
It went together without a glitch. All the parts were there and correct. The only missing item was one precut speaker wire. Not a problem. No schematic vs board marking discrepancies. Wish I could say that about my Grundig 800!
Will wrestle a bit more with the alignment tomorrow.
How did you figure out the order in which the IF's went?
Well, one can was obviously the local oscillator. Red core just like they usually are. Then I went to Mouser's listing and they identify the 1st, 2nd, 3rd IF by color. First two matched. Only one left so it must be 3rd. Maybe a slightly different turns ratio. Plus they had numbers on them zx-920 thru -923. That lined up as well.
Must be correct. They all peaked up nice and sharp.
I figured either the color coding, or resistance measurements on each of the two IF can coils.
Can you post the colors for the 1st, 2nd, and 3rd IF's?