My 2nd board is headed to Shadetree Mechanic when it arrives later this week. Maybe he'll do a video for us.
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Negative Peak Compression boards for Cobra 29
- Thread starter FredTx63
- Start date
I'll wait for the model with the Kaiburr Crystal Technology. Red, Blue, Green, Purple model boards.
nomadradio this might help about the ground i sent him a message about when he was getting more and about the ground here is his replied=
New message from: radiojoe757 (1,401
)
Chassis mount ground is because the board is mounted to the chassis. In the old Cobra 29's the chassis was floating, to protect against positive ground vehicles. I don't think they have made any positive ground vehicles in 80 years so this is no longer an issue. I believe Cobra has stopped making floating ground radios, so mounting this board to the chassis of the radio would cause no problem. But if you have an older radio, you will need to add a ground wire, to DC ground the board.
I found two more sets of boards and will be listing them shortly. Ordered more parts, and boards assembled, but that may take many weeks to come together.
New message from: radiojoe757 (1,401
)Chassis mount ground is because the board is mounted to the chassis. In the old Cobra 29's the chassis was floating, to protect against positive ground vehicles. I don't think they have made any positive ground vehicles in 80 years so this is no longer an issue. I believe Cobra has stopped making floating ground radios, so mounting this board to the chassis of the radio would cause no problem. But if you have an older radio, you will need to add a ground wire, to DC ground the board.
I found two more sets of boards and will be listing them shortly. Ordered more parts, and boards assembled, but that may take many weeks to come together.
I hear that a shard of that Crystal can be used for Lightsabers ....
That will certainly cut thru the mud...
Hmmm...
Ugh...this is not good...
You want better advice?
Try that heat sink panel - the one the Final and Driver mount to - that is at the same potential as Negative FOIL BOARD Ground - drill and mount...
(...I can't believe this...)
(it's the 80 years part that; "No, you don't know Datsun and Subaru very well..." - It's why Datsun went bust and got gobbled up by Mitsubishi and Nissan to name a couple...)
You want better advice?
Try that heat sink panel - the one the Final and Driver mount to - that is at the same potential as Negative FOIL BOARD Ground - drill and mount...
(...I can't believe this...)
(it's the 80 years part that; "No, you don't know Datsun and Subaru very well..." - It's why Datsun went bust and got gobbled up by Mitsubishi and Nissan to name a couple...)
You're just sending (throwing) your money (pocket cash - burn money) to someone else...
I have some thoughts on this but it will have to await another day...
I have some thoughts on this but it will have to await another day...
why andy why wait today it's a good day for it, here is my idiotic 2cents i just don't see it jp36 is just a voltage path to the final how in earth 2 or 3 ic chips resister suppose to clean up mu audiooooooooo LOL
Shadetree Mechanic
Delaware Base Station 808
The traditional jp36 mod puts a capacitor and resistor combo in place of jp36 in order to create more "swing" for the watt meter in an effort to make a cb amp more linear in operation and is effective in waking up a sleepy amplifier.
The resistor value in the combo sets the dead key. If a variable dead key is needed, then the addition of a transistor controlled by a pot on the front of the radio is the reliable way to do it.
This new board does all this plus NPC or negative peak control. Compression of the negative peaks in the modulation envelope, allows the positive peaks to exceed %100 without clipping the negative peaks. Keeping the negative peaks from exceeding %100 and flat lining will keep it from sounding like a scratchy over modulated dump truck radio. This technique is also used to improve cb amp use. But this board description claims a type of pseudo NPC, we won't know what that actually means or how effective it will be until someone here can get one and report back.
This is the way I understand these three modifications and I will be doing a side by side test of them soon.
The resistor value in the combo sets the dead key. If a variable dead key is needed, then the addition of a transistor controlled by a pot on the front of the radio is the reliable way to do it.
This new board does all this plus NPC or negative peak control. Compression of the negative peaks in the modulation envelope, allows the positive peaks to exceed %100 without clipping the negative peaks. Keeping the negative peaks from exceeding %100 and flat lining will keep it from sounding like a scratchy over modulated dump truck radio. This technique is also used to improve cb amp use. But this board description claims a type of pseudo NPC, we won't know what that actually means or how effective it will be until someone here can get one and report back.
This is the way I understand these three modifications and I will be doing a side by side test of them soon.
JP36 mods actually break the feed for the Driver, not the Final.
Why does it have to be a scratchy over modulated dump truck radio? Lol. When you gents figure this out build me one.
This guy clearly does not know his automotive history! Europeans were big on positive ground. The only reason the USA and our negative ground won out was because we were a bigger market for European brands than Europe was! LOL In the 1980's and 1990's I was still working on the occasional old + ground vehicle. My grandfather who has been dead for a long time actual drove commercial vechiles that sometimes had positive ground systems.nomadradio this might help about the ground i sent him a message about when he was getting more and about the ground here is his replied=
New message from: radiojoe757 (1,401
Chassis mount ground is because the board is mounted to the chassis. In the old Cobra 29's the chassis was floating, to protect against positive ground vehicles. I don't think they have made any positive ground vehicles in 80 years so this is no longer an issue. I believe Cobra has stopped making floating ground radios, so mounting this board to the chassis of the radio would cause no problem. But if you have an older radio, you will need to add a ground wire, to DC ground the board.
I found two more sets of boards and will be listing them shortly. Ordered more parts, and boards assembled, but that may take many weeks to come together.
In fact it is just like various fasteners that did not follow " Righty Tighty-Lefty Loosey" was not isolated to British products and bicycles Chrysler did that with their lug nuts for a while in an attempt to generate sales for parts at dealerships to keep people from buying cheap and widely available leg nuts some place else!
In fact in the 1980's and 1990's you could still buy after market audio radios, cassettes and CD players that would work with positive ground systems and audio amps.
Very interesting. I would love to try this little board in my Uniden 78XXX. I can never recall the letters that follow it only that it is almost identical to a CObra 29 and mine was not made in China it was one of the last ones not made in China! LOL It is NOS and it would be perfect for this!