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Cobra 18 WX ST II (don’t laugh)

A quick Goggle search turned up a manual full of clues....
I popped the covers off of my 18 ultra, it s the older version of the ST2 but it might be close.
Nope, my old school version is totally different. It says VR2 is the modulation pot but my pots have different numbers and the board layout is totally different. From the factory the modulation is set to about 90% so it could be turned up a little. Using another radio with no antenna and headphones as a monitor, you could turn it up until it sounds a little scratchy and then back it down a little.
 
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Now, the 18RV and the 18ST 1st Generation - are different - one had "grey face" while the other 18 (later version) had just the ST suffix and had a Black Face but the ST unit was MECHANICAL switch - as well as the WX - but had a SCAN function for channels making it unique in performance and undocumented features - subjected to squeals and used VERTICAL BOARDS that broke - I have personal experience in that one - including it's frailty of surviving even a minor impact

So to get one that works, enjoy - they don't always survive the jostling you can get with vehicles in mobile setups...
 
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Now that I’m only using a steel whip atop a 5-inch Hybrid Micro atop a 3-foot tripod and one wire radial, I am in full stealth mode. :cautious: Meanwhile my SWR on 11 meters is flatter’n one of Joe’s pancakes down at the diner, AND I can still play ham on 6-40 meters. (y) Throw in a devilish mic and an Italian mystery box (albeit a puny one) and all is right with the world. :p

I ain’t the only nascent writer hereabouts.

.
 
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All of those different models of the 18 made me go look up my old one. It was the 18 Ultra.
1b2f732b-d03e-41ca-8cfb-1c0b264ee05f_largesize.jpg
 
All of those different models of the 18 made me go look up my old one. It was the 18 Ultra.
1b2f732b-d03e-41ca-8cfb-1c0b264ee05f_largesize.jpg
I found out that the microphone on the ultra is an excellent mic. Clear and loud, louder than my 636. I transposed the AMC mod from the Cobra 29 and this old ultra is sounding great. Working on transposing the jp36 mod now. I will start a new thread when I get it all figured out.
 
If you know of a good shop to do your radio, you could do the adjustable deadkey mod like the cobra 29 JP36 variable dead key mod. I don’t have an 18 in front of me so if there ain’t a Jumper available, they need to cut a trace and install the mod there

View attachment 34221
Thanks for the diagram,I just did this to my Ultra. I will add what I did in case anyone has one. The schematic is a little different, instead of putting it at L19, the Ultra is RFC301 and the negative side of the cap goes toward this coil. I ended up with 470uF and 220 ohms. This gives it a 1.5w dead key which makes a 30w dead key on the 203.I also did the AMC attack mod which makes the modulation limiter come on a little softer when it activates. I changed C503 to 4.7uF and with the pot all the way up, it would hit 20w peak. I turned the pot down so it gets about 15w, I don't want to be too hard on it. It still makes the 203 do over 150w peak. This radio is a real talker, I had no idea what it was capable of.

IMG_20200224_223929473.jpg
 
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