convert AM/FM home stereo to shortwave?

[wenzeslaus]

a while ago I read about how to convert an AM pocket radio to shortwave. it was a crude method, just wrap a another wire a few turns around the ferrite bar and attach it to the right points on the tuning system. usually done in communist countries where news of the outside world was forbidden and shortwave radios were unavailable.

lately I want an AM/FM analog home stereo with a nice big long tuner, to connect to a big antenna for DXing.

then I put 2 and 2 together. why not modify the AM frequencies to shortwave? it's only a matter of L and C. and use the external AM jack on the back for a long wire SW antenna. even if it takes bolting an air gap variable capacitor on top of the cabinet.

adjust frequency coverage and tracking so the tuner is now 2.3-18 MHz and ignore the numbers on the scale or print out your own scale and tape it on.

can it be done? if so, can anybody come up with specific instructions?

 

[a417]

can it be done? if so, can anybody come up with specific instructions?

It can be done, but I am sure that there will be highly specific device dependant instructions - beyond what you already coarsely described.

 

[prcguy]

With an old L/C tuned local oscillator that was ganged to the antenna trimming cap it was not that difficult. Most modern AM/FM receivers have synthesized local oscillators and you would have to modify that with either mapping out the PLL synthesizer or changing a crystal to tune outside the original frequency range.

 

[majoco]

The short answer is .....no.

 

[wenzeslaus]

With an old L/C tuned local oscillator that was ganged to the antenna trimming cap it was not that difficult. Most modern AM/FM receivers have synthesized local oscillators and you would have to modify that with either mapping out the PLL synthesizer or changing a crystal to tune outside the original frequency range.

yep. not interested in modern PLL digital tuning. I was talking about analog.

I want one of these

hate to butcher it though

 

[wenzeslaus]

The short answer is .....no.

I think with a little bit more of an answer that might turn into a Yes.

 

[WB5ITT]

You would do better getting a REAL SW tuner. Period

 

[dlwtrunked]

a while ago I read about how to convert an AM pocket radio to shortwave. it was a crude method, just wrap a another wire a few turns around the ferrite bar and attach it to the right points on the tuning system. usually done in communist countries where news of the outside world was forbidden and shortwave radios were unavailable.

lately I want an AM/FM analog home stereo with a nice big long tuner, to connect to a big antenna for DXing.

then I put 2 and 2 together. why not modify the AM frequencies to shortwave? it's only a matter of L and C. and use the external AM jack on the back for a long wire SW antenna. even if it takes bolting an air gap variable capacitor on top of the cabinet.

adjust frequency coverage and tracking so the tuner is now 2.3-18 MHz and ignore the numbers on the scale or print out your own scale and tape it on.

can it be done? if so, can anybody come up with specific instructions?

(The above sounds a little like you *may* have things backwards as you will need to decrease inductance (fewer turn) and lower (not add capacitance) unless you remove the old components. ) There are usually at least two tuned circuits so that will at least double your work and getting them to track together for good reception can be nontrivial. and you will have no indication of the frequency that you have tuned. I have done the reverse. about 50 years ago, I took a car radio, added capacitors so that I could listen to longwave aeronautical beacons. What ever you do ion this idea, you can cheaply buy better.

 

[wenzeslaus]

well yeah, but the tuner isn't 20" long and doesn't have that sweet lead-weighted tuner action

 

[wenzeslaus]

(The above sounds a little like you *may* have things backwards as you will need to decrease inductance (fewer turn) and lower (not add capacitance) unless you remove the old components. ) There are usually at least two tuned circuits so that will at least double your work and getting them to track together for good reception can be nontrivial. and you will have no indication of the frequency that you have tuned. I have done the reverse. about 50 years ago, I took a car radio, added capacitors so that I could listen to longwave aeronautical beacons. What ever you do ion this idea, you can cheaply buy better.

that's what I said, a few turns. and I don't care about the freq not matching up on the dial, I can use the log scale or print my own scale and tape it on.

 

[MUTNAV]

Or you could try hooking up a converter to it. No mangling necessary

http://techlib.com/files/convert.pdf

or

http://techlib.com/files/rushconv.pdf

All will be limited to the 1 Mhz bandwidth of the original AM tuner though, that can be gotten around with multiple devices.

Techlib.com has some great stuff in it BTW.

Thanks
Joel

 

[RFI-EMI-GUY]

^^^^^ BEST ADVICE...

 

[RFI-EMI-GUY]

There were converters to add shortwave to a car AM receiver. They have a bandswitch. Might find one on e bay under antique electronics.

 

[wenzeslaus]

Or you could try hooking up a converter to it. No mangling necessary

http://techlib.com/files/convert.pdf

or

http://techlib.com/files/rushconv.pdf

All will be limited to the 1 Mhz bandwidth of the original AM tuner though, that can be gotten around with multiple devices.

Techlib.com has some great stuff in it BTW.

Thanks
Joel

that's a bit more work than I want to put into it. might consider buying one. but then it's limited to 1 MHz bandwidth. need to add circuits to create SW bands.

 

[wenzeslaus]

There were converters to add shortwave to a car AM receiver. They have a bandswitch. Might find one on e bay under antique electronics.

 

[MUTNAV]

that's a bit more work than I want to put into it. might consider buying one. but then it's limited to 1 MHz bandwidth. need to add circuits to create SW bands.

then there will probably be more work than you are imagining, if you want to get everything 2.3 to 18 Mhz then the receive bandwidth is going to have issues if you go for more than the AM bands bandwidth.

It would probably be easier to buy or build a converter and then use plug in coils and crystals to change bands.

Personally I would go that route or the bay route, since the AM receiver is beautiful by itself...
You could have a real showpiece there.

Have you ever seen what people think of modified radios? even radio kits !

Thanks
Joel

 

[wtp]

i did get a very cheap AM,FM to get some air band stuff.
but it was a throwaway thing from a neighbor, not a piece of art tuner.

 

[RFI-EMI-GUY]

Nice!. Those buttons are in meters, so some sort of tuning chart must have come with it.

 

[RFI-EMI-GUY]

More info here:

Kurzwellenvorsatz KWV1000 Converter Grundig Radio-Vertrieb, RVF | Radiomuseum

Kurzwellenvorsatz KWV1000 Converter Grundig Radio-Vertrieb, RVF, Radiowerke, build 1970–1979, 13 pictures, 5 schematics, 2 semiconductors, Germany

www.radiomuseum.org

 

[wenzeslaus]

i did get a very cheap AM,FM to get some air band stuff.
but it was a throwaway thing from a neighbor, not a piece of art tuner.

got a story about that. back in the early 80's my sister's friend's little brother wanted to sell me his stereo he didn't want

I said I'd buy it for 10 cents. he said okay. but all I had was a quarter so I made him go to the store and get change. took him 30 minutes to walk there and back.

then when I got it home I was totally baffled by the speaker terminals, what kind of connector do you plug into these?

so I called up a stereo store and my dumb junior-high ass is trying to describe what I'm looking at and what I'm trying to figure out to a salesman on the phone, to say the least, I didn't get anywhere with him took me a week to figure it out myself