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[Solved] Which crystal and where to buy to get Channel 36 and 37 on a Midland 13-893?

D

doffo

Well-Known Member
Oct 14, 2012
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Hello fellow CBers!

Making sure if I got this right. The Midland 13-893 is essentially a Cobra 138 23 Channel SSB radio. That being said, according to this page, one would need a 8.549 MHz crystal to obtain Channel 35, 36, 37, and 38. 138,139, Midland 13-893, 13-895 Crystal Mixing According to that link, all 3 are added up to give you the final frequency. I just first added 11.0035 + 7.8025 to get 18.806. Then I did 27.355 - 18.806 to give me 8.549. Just making sure I did that right to figure out which crystal to try and get.

That being said... Where to buy a crystal that could work? :) I didn't yield much luck in results or a good place to buy some.
Thanks for reading and any help. Enjoy the day and some radio time!
 

doffo said:
Hello fellow CBers!

Making sure if I got this right. The Midland 13-893 is essentially a Cobra 138 23 Channel SSB radio. That being said, according to this page, one would need a 8.549 MHz crystal to obtain Channel 35, 36, 37, and 38. 138,139, Midland 13-893, 13-895 Crystal Mixing According to that link, all 3 are added up to give you the final frequency. I just first added 11.0035 + 7.8025 to get 18.806. Then I did 27.355 - 18.806 to give me 8.549. Just making sure I did that right to figure out which crystal to try and get.

That being said... Where to buy a crystal that could work? :) I didn't yield much luck in results or a good place to buy some.
Thanks for reading and any help. Enjoy the day and some radio time!
Click to expand...
8.559 = 27.365-27.405 ....8.549 = 27.355- 27.395....good luck finding a crystal for a reasonable price
 
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doffo said:
That being said... Where to buy a crystal that could work?
Click to expand...
You would likely have to get one custom made. Not cheap. And crystal manufacturers are few and far between these days. And most have minimum orders (usually in the hundreds of units!).
 
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I have not purchased anything from them, just found on the net.

AudioShockwav

Thread 'Someone asked about Crystals'

I don't remember now who it was but someone was asking about where they could find crystals, and I ran across this website today.
www.klove.nl

CRYSTALS | KLOVE | Frequency Technology

Klove Electronics manufacture a wide range of quartz crystals to suit virtually all applications, including high and low frequency.
www.klove.nl
Might help someone....

73
Jeff
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73
Jeff
 
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What if, instead of switching the 8MHz "A" crystal, you swap the 7.8025MHz "C" crystal with the 8.12MHz crystal found on Kens Electronics and pull it to 8.1225? 2.5kHz should be within the pull range of a single crystal. That would move the entire dial to 27.285-27.555.
 
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doffo said:
Makes me wish there was some New Old Stock of the 40 channel conversion kits sitting somewhere lol.

Beta-Com Switch
Click to expand...
You could probably fake something up with a rotary encoder, arduino, Si5351 (or two), a couple of flip flops, and some passives for "brick wall" filters. Use the outputs of the Si53151 to generate signals twice what the crystals would have and use the flip flops for divide by 2 circuits, just to cut down on jitter. Feed those through the filters made out of the passives to get rid of harmonics. Take the filtered signals and use them as inputs to the original mixers. You could even modify the original oscillator circuits to be buffer amps if you wanted to.

I know, way off topic, but I've been kind of wondering lately why nobody's been doing something like this to give new life to radios that currently use a crystal matrix to synthesize their frequencies. At least for solid state radios, anyways.
 
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TM86 said:
You could probably fake something up with a rotary encoder, arduino, Si5351 (or two), a couple of flip flops, and some passives for "brick wall" filters. Use the outputs of the Si53151 to generate signals twice what the crystals would have and use the flip flops for divide by 2 circuits, just to cut down on jitter. Feed those through the filters made out of the passives to get rid of harmonics. Take the filtered signals and use them as inputs to the original mixers. You could even modify the original oscillator circuits to be buffer amps if you wanted to.

I know, way off topic, but I've been kind of wondering lately why nobody's been doing something like this to give new life to radios that currently use a crystal matrix to synthesize their frequencies. At least for solid state radios, anyways.
Click to expand...
Ahhh. Something like this?

Midland 13-893 Ardurino project
 
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