Tecsun AN-200 Antenna - Defect Investigation
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- čas přidán 19. 08. 2024
- I like the AN-200 loop antenna and I've purchased a number of them over the past years. All have worked fine except one. For this one, I think the tuning capacitor is defective so I disassemble the antenna to see what's really happening. The disassembly turns out to be very challenging but I eventually reach a conclusion on the source of the trouble.
30 minutes in and its miraculously open? Thanks very helpful
Trace and draw the circuit ... 1st thing ! Then check continuity/open coils and shorts between coils. Check capacitor for shorts.
Those polyvaricons are a standard item, and can be found in any older transistor radio with a string type dial pointer. AM only types have two seperate sections, AM/FM types have 4. Either will work. even the mounting holes are identical. New, they only cost a few pennies.
The loop has relatively high Q and need ver sharp, precise tuning, which is difficult achieve. Nothing wrong with your antenna.
That was 26 mins of pain watching you take that to bits jim...well last time I watched your videos was 7 years ago..you definitely have come a long way jim you have all the technology for you repairing videos now..all the best jim..remember I learnd from you.now I do my own radios now as a hobby 😊
Great job on how you got this open....Nice work! 🙂👍🏻👍🏻
I do like these loop antennae’s. I paid $10 for mine, it was used. The antenna looks professional and great on top of any radio, very scientific. A larger one of course would work better and mounted put side. I keep my shop loop hooked up to my signal generator for transmitting purposes., when I played records with audio modulating my Sig- Gen. $10 to $20 is a fair price, me tinks.
Hi Jim !
That looks like a normal dual polyvaricon capacitor .
If so you can just move the connection's over .
Flip the pcb ( don't attempt de soldering the capacitor , heat kills these ) .
Remove the black screws from the stand-offs , re-attach them onto the pcb
, reassemble unit , fit screws & knob last .
Jim. I have the exact same model. I also struggled with disassembling it. Mine would get very scratchy while tuning. I doused the capacitor with electronic cleaner and deoxit and turned dial many times. And now it is quiet again.
I have one similar to this, base is different shape, but the same I think. On mine it looks like the cap is across the outsides of the big coil and the jack is three turns in the middle but a separate coil. I find it to be kind of weak but it does work if you have a radio with a meter you can see it pull up weaker stations. I had a homemade one for years that was nothing but a tuning cap from a pocket AM radio and maybe 125 ft or so of wire wrapped on a wooden frame about the size of a shirt box. It worked better than these do with anything with a bar in it.
I know it get frustrating....when your right there and just cant get it open.
I hooked mine up to a signal generator on the BC band. Then I would a loop of wire around the turns and connected the loop to a scope. Monitoring the loop pickup i could see radiated sine waves from the Signal Generator. Adjusting the tuning cap on the base I could see when I hit resonance at each frequency across the BC band. From the peak frequency and the capacitor values I could calculate the coil inductance. However thanks so much fir showing us how to disassemble the loop. I was very reluctant to tear mine down.
The Terk model is much easier to take apart with just a few screws. He needs a bigger hammer for this one!
Parents is running out watching...lol.
There are 28 turns of #22 wire, of which 3 turns are the secondary..
It works only on weak signals the best. I found that placing the coil at an angle to the right rear corner of a radio works most effectively. The coil is 28 turns of # 22 AWG. The cap is a standard unit like used in solid state AM radios. Its cooler looking than it is practical, but is does work well for its size.
M. Caldera has a mini whip antenna (I have watched Electronics Old and New videos)
I Once had a Antenna as such as the one jim is working on in this video! no one could figure out how to get it to work, but I plugged it into the wall with a multi style wall plug and ... it was running. perhaps, that is the deal here!
Are there rubber stoppers on the bottom of this...if so pull them off...underneath could very well be the screws.
Lol...wouldn't you know the flashlight wouldn't work.
I have one of those antennas but it's a Radio Shack antenna
Mine had a cold solid connection.....
Unless there's a screw under the sticker
The flash light....lol
The screws are captaved
Good job Mr. Jim.
É levando uma surra da pequena antena e quase fica louco de raiva.
Really Painful watch you try to Cut an Artery off !! ......Maybe Stamp collecting would be Safer ??
That woiuld make a good item to take apart at a job interview...you get it apart in 10 mins your HIRED.