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Find the modulation transformer. You'll see a diode in series with it going to the final and driver. Remove one end of the diode, and strap 3-7 more in series, and go from there. Will lower the deadkey, but keep the pep ratio the same. Makes for a REALLY loud radio. --Toll_Free

If you REALLY want to increase the complete talk-power on those units (I've been working with the 858 Unidens and the processors / clippers in them for about 25 years), add a diode or two to the POSITIVE side. This will still allow for some amount of clipping (good), but will INCREASE the...

Bill, PERFECT representation of what the scope shows. As long as you don't hammer the modulator, you can get as loud as it's capable of. Again, this circuit isn't for idiots. ANY TRANSMITTER CAN BE MADE TO SOUND LIKE SHIT! :) BUT, thanks for the clarification, with actual...

VA3ES, the Cobra 29 and other transformer driven modulation schemes in most CBs is ALREADY configured as an autotransformer..... Which is what timtron is advocating doing. W8JI is off his rocker on a lot of things. There's a reason he does private consulting now, and doesn't have a 'real...

Chances are it's a 150 to 160 watt PEP amp. SOME of those old things could be driven to about 225 watts PEP, but they LIKED being run near 140-160 watts. If you run it near 160 PEP, it's going to take every bit of 250 watts input. Being that it's AM/FM, and NOT ssb, then you KNOW it's a...

Comparing the Drake to a Bird is like comparing a Kenwood to a Cobra. --Toll_Free

Mac, you'd gain nothing. really want to make that amp sing, pull the DC feed OUT of the output xformers, and then feed DC through a SEPERATE DC choke. 10 percent or more gain doing this..... BUT, no, removing the chokes from the electrical center tap of the xformers won't hurt, won't...

I guess it's a question of semantics, then. To me, NPC was ONLY a way to keep the carrier alive. I didn't WANT it doing anything to my RF waveform. When you look at the NPC mod for the series modulated transmitters (Galaxy, Cobra, etc), you'll see it hooks the audio waveform JUST above a...

Chris, check out a SDR unit. You only need a receiver. That will get you Spec An, for cheap. The EASIEST way is a Softrock, centered on 455 Khz. THEN, take the output from your flavorite radio and stuff it into the softrock, and use powerSDR to take a snapshot of the RF spectrum you're...

As I now the owner(s) of Galaxy, Texas Star, Messenger and the original Palomar... Yes. Notice, I DID qualify my statement with usually.... --Toll_Free

Shockwave... You can't even keep a signal faithful with DC coupling. Their is the 'repeaking' effect that happens in ANY amplifier stage, especially one that is NOT perfectly flat in freq response (and find one that is, we BOTH get rich!!) The POINT is, you can GREATLY eliminate the...

Although what W8JI writes is COMPLETELY correct, it has nothing to do with a typical collector modulated CB radio, since they DON'T have a screen grid. You'd need a dual gate mosfet to approximate the same thing as a tet in the final. I only know of 3 CBers that would spend the money on a...

Sorry, but I bet you don't have a spectrum analyzer. Because you would see, with a transformer or other high level modulated AM signal, the carrier DOES drop when overmodulated with a NON NPC or other type of assymetrical limiter in it. As I stated, I HAVE one, and have actually WATCHED it...

Yes, that is D8. If you want to LOWER the deadkey of the radio, and still keep the same audio in proportion, you would ADD diodes in SERIES to this one, and D1 and D2 would still be put at each end of the entire chain. I lived in Colorado Springs for a short time, up in Cascade, too...

D1 is the actual sampling diode that turns D2 on during NEGATIVE peaks. The anti-spike diode actually (in this circuit) does dual-duty, it does anti-spike as well as prevents the keepalive voltage from being presented back to the xformer.... Which could cause problems galore, depending on the...

DINGDINGDING!!!!!! And that is EXACTLY why it can be used in ANY high level circuit, be it transformer coupled (plate or collector modulated) or series modulated (like Cobra 14x chassis, Galaxy chassis, etc). If you do this mod, with the 'class AB conversion" of the final in the galaxy /...

Yes, pushing a 1969 to 75 pep is REALLY pushing it. It's not a mod I'd push on to customers, it's a mod that I did (as well as quite a few others) back in the early part of the decade for the keydown scene. They do NOT last forever at that level... HOWEVER, it is a selling point when you can...

And your point is? Not like I took credit for it........ I'm still waiting for your explanation as to how the carrier is still their when their is no collector voltage....? Rather than try to steer the thunder... --Toll_Free

If you'd like MORE proof that Browning COULDN'T design anything solid state, take a look at the D300 and D80... BOTH pinnacles of achievement on Brownings side, the last radios they really made. Oh yeah, they are a Cobra 142 and Cobra 140, respectively. Their engineers saw the writing on the...

It's a hybrid radio. The IV has the SAME power supply components and needs (basically) as the 3. HOWEVER, the 3 DOESN'T have the 3.3, 5 and 12 volt supplies in it. The low voltage supplies where the biggest problem. Browning could build tube stuff, the solid state stuff they needed help...