Judgeing by the info in his post alone I'm going to go ahead and say this isn't an NPC mod. That's all marketing hog wash as far as I can tell...
It's the variable jp36 mod made up in SMD..
It's the variable jp36 mod made up in SMD..
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Negative Peak Compression boards for Cobra 29
- Thread starter FredTx63
- Start date
Shadetree Mechanic
Delaware Base Station 808
And to think I used to catch hades for Limiter mods...
And you guys let this pass...
And you guys let this pass...
Just curious. After doing a few swing mods on cobra 29 radios. Is there actually a swing mod that works and delivers a clean wave?
the signal produced is no longer am. monitor the voice modulated signal of that transmitter on any channel and ask yourself why you can hear it clearly on both upper and lower ssb. your "modification" has converted your am transmitter into a double sideband transmitter (DSB/SC) with suppressed carrier.
The waveform I posted is what you can see when you put a Steel Guitar thru a "Fuzz Box" and achieve the Same result.
Put it on a '45 and see if it finds the "Bullet"
Put it on a '45 and see if it finds the "Bullet"
NPC/assymetry mod for transformer modulated radios. It's there, on WWDX described somewhere.
Low_Boy posted:
"Just curious. After doing a few swing mods on cobra 29 radios. Is there actually a swing mod that works and delivers a clean wave?"
no, it's not happenning in a butchered am transmitter @ approximately 1.5W carrier with upwards of 40W pep @ a peak-to-carrier ratio of over 26:1. that's not am.
when measuring average power, a modulation depth of 100% added to a carrier of 100W produces a maximum of 150W of modulated output for an increase in power of 1.76 dB. or 1.5X, 1.5:1 peak to carrier.
dB. = 10 log (1 + ( M sq. / 2) )
M (modulation index = 1 @ 100%)
/ = divided by
sq = squared
when measuring peak envelope power, a modulation depth of 100% added to a carrier of 100W produces a maximum of 400W of modulated output for an increase in power of 6 dB. or 4X, 4.0:1 peak to carrier.
dB. = 10 log (1 + M) sq.
M (modulation index = 1 @ 100%)
/ = divided by
sq = squared
"Just curious. After doing a few swing mods on cobra 29 radios. Is there actually a swing mod that works and delivers a clean wave?"
no, it's not happenning in a butchered am transmitter @ approximately 1.5W carrier with upwards of 40W pep @ a peak-to-carrier ratio of over 26:1. that's not am.
when measuring average power, a modulation depth of 100% added to a carrier of 100W produces a maximum of 150W of modulated output for an increase in power of 1.76 dB. or 1.5X, 1.5:1 peak to carrier.
dB. = 10 log (1 + ( M sq. / 2) )
M (modulation index = 1 @ 100%)
/ = divided by
sq = squared
when measuring peak envelope power, a modulation depth of 100% added to a carrier of 100W produces a maximum of 400W of modulated output for an increase in power of 6 dB. or 4X, 4.0:1 peak to carrier.
dB. = 10 log (1 + M) sq.
M (modulation index = 1 @ 100%)
/ = divided by
sq = squared
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All the dump trucks going to our local gravel pit get chastised by for being over modulated. While working in close quarters they want the mic gain turned down to a more pleasant realm of 50%. Any use of echo, power mics, or splatter boxes are usually discouraged, especially first thing in the morning before their caffeine high kicks in.