500 channel musical hanger??

[357]

Someone was playing music on every channel from 27.005 to 27.505
Hows that possible?

 

[NZ8N]

**** re-post from earlier thread on the same subject ****

Found this mod in an old GE A model we bought at a yard sale.

GE was rusted out dead beyond repair it had been in a wet barn for decades.

But built a new circuit as above and put it in a working cybernet base radio.
And it works real good, put radio on channel 32 and it transmits on every channel from 23 to 40 at the same time. Never had so much fun with a dollars worth of parts.

Local ham wanted to know how the heck I did it. Told him I pulled the channel knob off and attached a power drill to the shaft and pulled the trigger. The funny thing was I think he believed me LOL

Not sure of how such a simple circuit works, i'm an electrician and radio tinkerer but no technician. Will forward this thread to our tech for an explanation if no-one can tell me how it does what it does.

Its not a fully wideband transmission though. Listening on a ham rig with a vfo and tuning up and down shows that the duplicated channels are only every 10K, i.e. you cant hear the transmission on 27.360 but you can on 27.355 and 27.365 megs.

The mod also works on reception. Put radio on channel 32 and you can hear conversations on every channel from 23 to 40 at the same time. But nothing is received when the ham radio rig transmits on a zero frequency such as 27.360 megs. Strange.

Any explanation how this thing works without getting too technical?

Loz!

Probably similar to this. They disconnected the Lock Detect from the PLL (enabling the Transmit) and fed it into an inverting Comparator circuit that feeds the VCO voltage in parallel with the output of the PLL low pass filter (other side of the LM358 (pins 5,6,7) biased to 1/2 VCC). This causes the Programmable Divider to flip up one channel, then down one channel, then up 2, down 2, until it finds a lock. Which it won't. As the Phase Detector comes into lock, the Lock Detect flips, then the Comparator causes it to flip back the other way. So it "locks" (then unlocks) on multiple frequencies or channels, whatever the step rate of the Programmable Divider is.

 

[Handy Andy]

Was it music from, say; a tiny toy sounder found in some ornaments and Xmas toys?

...those things are horrible IF noise generators.

Some of that knockoff stuff use a timing Xtal close to the IF strip passbands of some receivers - stereos and such.

 

[dave457]

Here's a breakdown of how it works

 

[dave457]

Here's a breakdown of how it works

 

[nomadradio]

More than one way to skin that cat. We used a 10.24 MHz crystal like the one in a radio, and a chip that takes that frequency and divides it in half ten times.

This gets you a very stable and accurate square wave at 10 kHz. Feeding this into the PLL circuit's VCO tuning voltage will get you a "clone army" of separate, distinct AM signals, separated at 10 kHz spacing.

Does lead me to wonder what kind of trouble I'd get into for selling a pc board that does this trick?

Wasn't banjo music you heard, was it?

73

 

[Rwb]

More than one way to skin that cat. We used a 10.24 MHz crystal like the one in a radio, and a chip that takes that frequency and divides it in half ten times.

This gets you a very stable and accurate square wave at 10 kHz. Feeding this into the PLL circuit's VCO tuning voltage will get you a "clone army" of separate, distinct AM signals, separated at 10 kHz spacing.

Does lead me to wonder what kind of trouble I'd get into for selling a pc board that does this trick?

Wasn't banjo music you heard, was it?

73

thats funny .bet they best run faster

 

[357]

a birdie told me its fine tune cb shop