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Old 16th Sep 2021, 12:31 pm   #1
Martin_Calva
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Default Where to buy off the shelf AM modulator?

I have finally got my Ekco CR 227 car radio working.

I am in France and MW broadcasting seems to have ceased in France. But I'd like to be able to drive along with music playing from the radio despite the absence of MW broadcasting.

My question: Is there available a unit that can take an audio signal (from a CD player for example) and generate an AM signal on medium wave frequencies?

Last edited by Cobaltblue; 16th Sep 2021 at 12:43 pm. Reason: Automotive removed
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Old 16th Sep 2021, 1:04 pm   #2
mickm3for
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Default Re: Where to buy off the shelf AM modulator?

Hi not off the shelf but the minimod project https://vintage-radio.net/forum/show...hlight=minimod will do it Mick
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Old 16th Sep 2021, 4:50 pm   #3
Martin_Calva
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Default Re: Where to buy off the shelf AM modulator?

Quote:
Originally Posted by mickm3for View Post
Hi not off the shelf but the minimod project https://vintage-radio.net/forum/show...hlight=minimod will do it Mick
Many thanks for that useful info. Because of my backlog of yet-to-be-completed projects, an off-the-shelf one would be better if available anywhere.

Years ago I bought a ready to use FM modulator. I suspect it was intended for pirate radio operators. I used it, fed from a Marconi low distortion oscillator, to generate a modulated FM signal that I could use to measure the frequency characteristics and distortion of FM receivers and tuners. The unit itself produced surprisingly low distortion when fed with a sinusoidal modulating signal. I don't know if an AM counterpart was available back then.
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Old 16th Sep 2021, 5:37 pm   #4
DavidEsp
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Default Re: Where to buy off the shelf AM modulator?

This guy (Tony) has a couple of models of 100 mW medium wave PLL transmitters/modulators. The Hurricane is easiest to use if you like exploring different frequencies. Also you can send audio to it via bluetooth and can monitor and control it from a smartphone app (his Android one or a generic Bluetooth Terminal app with preset buttons on iPhone etc.). Or the Spitfire is cheaper if you just want to set it to one frequency and forget it. I am not associated with that company or either of those products.
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Old 16th Sep 2021, 7:40 pm   #5
paulsherwin
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Default Re: Where to buy off the shelf AM modulator?

These microtransmitters are not suitable for using in a car though, at least without a fair bit of fiddling.
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Old 17th Sep 2021, 3:45 pm   #6
Martin_Calva
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Default Re: Where to buy off the shelf AM modulator?

Paul, could you elaborate on that? From a quick look I think the units will operate on a 12V dc supply so I'm not sure what would need to be fiddled so they could be used in a car.

Thank you David. Those units look so far as I can see suitable for what I have in mind.
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Old 25th Sep 2021, 8:35 am   #7
Martin_Calva
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Default Re: Where to buy off the shelf AM modulator?

It seems that in the 1960s in the USA small FM radios providing an AM output were often sold as FM adapters for use with AM only car radios. No shortage of them on Ebay.com.

https://www.ebay.com/itm/22461797562...MAAOSw-ehhOq6d

One such unit is winging its way to me now and I should have it in operation soon if all goes well.
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Old 25th Sep 2021, 9:50 am   #8
Herald1360
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Default Re: Where to buy off the shelf AM modulator?

That device should get you FM stations via your AM radio. Next you'll need an FM modulator to feed your other sources into the AM radio via the Sparkomatic

Hopefully it won't live up to its name
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Old 25th Sep 2021, 10:12 am   #9
paulsherwin
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Default Re: Where to buy off the shelf AM modulator?

Quote:
Originally Posted by Martin_Calva View Post
Paul, could you elaborate on that? From a quick look I think the units will operate on a 12V dc supply so I'm not sure what would need to be fiddled so they could be used in a car.
I only meant that physical installation in a car wouldn't be straightforward, though it could certainly be done.
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Old 25th Sep 2021, 12:19 pm   #10
Panrock
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Default Re: Where to buy off the shelf AM modulator?

There's a unit from the US known as the "Redirad". The UK dealer's site is no longer up though. I see there's still a site in the US.

I once fitted such a unit to a friend's automobile. It plugged in series with the aerial lead and provided a medium wave signal on 1000 KHz, deriving the programme material from a flylead tipped with a 3.5mm jack, which you plugged into your audio source. When you tuned to a 'real' MW station on the set, it could sense this and reverted to passing the radio signal straight through. It worked well.

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