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need lower dead key for my cobra 1000

King Mudduck

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May 6, 2005
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285 South Western Virgina waving!
Now it's 8 watt key with very little forward swing. If i set the key lower using L13 to around 3 watts is only swings forward a half a watt on average instead of peak meter reading. I have surfed the net and can not find any tips for this mod. Anyone out there have any ideas?

Also.......what kind of board is in the cobra 1000, is it the same a say a Cobra 29?
 

Zacarey T / Dwight D although seems close to the 29. L17.16 and 13 are power pots , not sure what your looking for here in a mod ? 8 watts seems a lot of DK for that radio unless it has a bigger final in it ? realistically , the 1000 should do 5 to 20 or so at 100% audio unless finals have been changed.
 
I tuned it using the info i could find on the net and it works and sounds just fine, other then the high key. The problem is that if i turn the key lower using L13 to around 3 to 4 watts it will only do around 10 watts but if i turn the key up to where it does around 25 watts ( PEP reading ) the key is up around 7 or 8 and that's to high for any of the amps i use. I'm looking for a mod that i can get the key down to 2 or 3 watts but still swing to 20 + watts.

I know i'm always the one preaching to everyone that they should have a clean radio but this is just something i'm playing with to use with a small tube amp to talk to the locals. It's a nice radio and already has an old connex board in it plus high and low channel's, i just would really like to have the key lower than it is now.
 
swing mod(lowers the deadkey and keeps the maximum pep)...and shouldn't that be the same as a 200GTL but no sideband?

never mind found some stuff

Cobra 87GTL, 89GTL, 1000GTL
Remove C128 (.47uf) & TR16, Change R132 (1k) to a 470Ohm,Change C61 (220pf-NPO) to a 270pf-NPO, Change R50 (3.9Ohm) to a 1Ohm, Change R47 (1Ohm) to a .47Ohm, Retune L17, L13, L12, L11 for MFP


and can do the 29 swing mod :)
good luck and may the CB gods be with ya :)
 
I can totally understand the swing thing , but your 1000 at 2 or 3 watt DK swinging 8 to 12 would work just fine for your amp of choice , and the audio would still be off the scale unless you turned it down after you lowered the DK , but like I said , the swing thing will work just fine as well , just one way is cleaner then the other. (as "they" say) :wink: Good luck and have fun.
 
if L13 is adjusted for anything but maximum carrier output the tank is operating out of resonance. in so doing the back emf or "flywheel effect" is reduced and so is the peak modulated power output. since the transmit audio is supplied to the collectors via a xfmr the only way to properly reshape the peak-to-carrier output without diminishing power is to modify the negative peak clipping circuit by altering the rc timing constants. done properly will yield 1.75 - 2.50W of carrier and approximately 20 - 25WPEP output. power levels within this range generally provide 4:1 peak-to-carrier output from most transistor amplifiers when operated at the highest power level. high power = low drive, medium power = medium drive and low power = high drive.
 
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if L13 is adjusted for anything but maximum carrier output the tank is operating out of resonance. in so doing the back emf or "flywheel effect" is reduced and so is the peak modulated power output.

moderators delete this post.

you should ask to have both your posts deleted, since you do not tell the guy how to do it.
just a bunch of big words that he wont understand and no mod instructions.
 


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