0033 - Elenco AM/FM-108CK Kit Build: Part 1
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- Опубликовано: 12 сен 2024
- First in a series of videos on building the Elenco AM/FM-108CK kit. In this part we build and test the IC amplifier.
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Off to a good start Bill!! Glad you like the kit and took the suggestion on starting a build video series!! Thanks for all of your help!!
My pleasure. And thank you too.
The instructions say in the first test to set the "volume control to half" not the volume to half, which may be why your result didn't fit the gain bracket they specify. I think you may have over-thought the test :)
This is an expensive kit, although its not really a kit in the normal sense, its a training course with the pcb and components supplied, and in that context its actually very inexpensive, and I am impressed with the quality and depth of the materials supplied that I have seen so far. One thing that impresses me most is that its not just saying how each bit works, its getting the "student" to make measurements, calculate relevant parameters and setting them up to understand how to diagnose faults in the future by tracing signal paths. I look forward to seeing the other videos in this series.
Thanks for the comment Ian.
Indeed they do, and I tried that off-camera. The result was a gain of about 58. The reason is, the pot is (correctly) a log taper pot. Not linear. The LM386 has an open loop gain of 200, so a gain of 100 is -3dB. So to get their desire for "half" power or more (100-180), the pot needs to be at 50% (or more) of it's resistance value. With a log taper pot, that would be more like "turn volume control to 3/4". Anyway, I took the -3dB route to get 1/2 of the power. Perhaps they had a linear pot in there at one time and neglected to update the instructions when they moved to a log pot. Who can tell?
But you're right. This amounts to an electronics course in commercial band radio receivers. Really nicely done and well worth the cost.
@@uni-byte The cost is reasonable if you are a US resident, but for those overseas the cost doubles due to US International postage rates. The manual is available on-line, so it might be possible to construct a AM radio similar to this using an inexpensive kit of parts from the usual Chinese suppliers. Some of these are worth purchasing just for the tuning capacitor. It might be difficult to correctly identify the IF transformers, however. Some Chinese kits use ceramic resonators in place of the IFs.
That was fun. I'll watch them all. I have a broken one of these, but no manual. I'm competent to just fix it, but I'll watch your build before I fix mine, and make the fix and alignment very easy. Thanks.
Thank you!. I think I linked to the manual in one or more of these videos. Good luck with the repair.
Yay! Can’t wait to watch all your videos! Just subscribed! … I’ve got the same exact kit that I’m about to start on. Question: The kit comes with lead-free solder, which I ABSOLUTELY HATE! It’s not nearly as good as traditional solder! Will it be ok to use my regular 60/40 (Tin/Lead) rosin core solder that I’m used to using, or is there something about this printed circuit board or foil/solder pads that would make using my regular 60/40 a bad idea? I have plenty of fume extraction, fans and air filtration to keep the lead smoke out of my face… Thanks! 😊😊😊
Thanks Steve.
Yes, 60/40 solder is what I'm using and it's doing fine. I am also no fan of lead-free solder. The board is probably tinned with lead-free, but they are compatible and you will have no issues using 60/40 or 63/37.
I built that in college. It’s a fun project.
It is indeed turning out that way. Thanks for the comment.
@@uni-byte no problem. It’s a nice radio. You can rig an led to the on/off switch to know when the radio is on or off. I don’t remember any other modifications I made, but that radio worked for a very long time. That brand also makes an bench power supply kit, I built two of those and they still work after years and years.
They do have a couple of nice power supplies. Not cheap though, but probably worth the price. Sorry for the late reply. YT marked this a spam. No idea why.
Great quality of paperwork. Some kits come without schematics or even worse, with wrong schematics.
Yeah. This series of Elenco kits especially. Well detailed, well thought out and very educational. Although most of the Elenco kits are pretty good too. But they do cost more.
I got this kit a few days ago, and have started the build. I didn't see your build of the Transistor Audio Amplifier Circuit Board in Section 1B of the Instructions. Did you do it? After you build this little circuit board, you take the IC off the main board, and plug this Amp board into the IC Socket and then do some tests. Is this just for educational purposes to show that the little IC does the same thing as this big supplemental circuit board? If so, what do you do with the constructed amp board? You don't use it and the IC for the radio, I assume?
I didn't build it yet. Maybe I'll do it as a part of one of my monthly kit builds. There would be something to learn from building it as they do a pretty good job of explaining how it works. I guess you just use what you find most aesthetic (visual or audio).
I am working on this kit. You have the same manual I do that calls out Capacitors C39 and C43 as non-polarized lytics. However, the capacitors that are in the kit for those numbers are polarized lytics. There are older manuals that call those as Lytics and shows C39 mounted on the copper side. I am assuming you just put the polarized versions in there and ignored the manual?
I guess technically I ignored the manual, but they don't give much choice. The polarity for C39 and C43 is clearly (more so for C39) marked on the on the board and there is no electronic reason for them to be non-polar.
I love it good 👍
I'm glad you like it
where can i buy the kit to build it. every website i visit is selling the built one. please help
I see them at Robotshop, TEquiment and at Elenco. They all seem to have them in stock. Never seen anyone sell a built one though. They may show pictures of it built, but it is indeed a kit.
@@uni-byte thank you so much
I think the jumper wire just makes an easier test point.
Maybe. Do they use it for that later on in the build?
@@uni-byte Yes sir.
I noticed that you didn’t move the lead to the jumper as it said in the book. I only ask for when I do it as directed in the manual I lose my time and have zero voltage. Any ideas? Maybe my volt meter is loading the circuit?
I meant tone, not time. 😊
@@kenmccarthy8130 Hmmm, you are right. An oversight on my part, but I did try it later and got overall better gain. Not sure why you lost the tone when you did it. What meter did you use?