Beginner questions, bear with me please.

I think you also need to upgrade the driver or you won't see much of an improvement. To be honest at best you might see 10 more watts even when done correctly, no one will really notice. If you want to make a splash look into an RFX-75 mod for that radio, probably easier then the final swap.

Cutlass327 said:

I have dabbled around here/there with CB for over 20 years now, never really got heavy into tuning and tweaking though. I have thought of doing some more in-depth stuff here and there, but my issue is equipment. I have a Dosy and a good DVOM. I am familiar with the components and how they work, but not what they exactly do in a CB. I took Electronics Engineering classes, one term from finishing the degree, but they never really seems to get into things much - put this together on the breadboard and see what it does - seems to be about the extent, and trying to learn programming from a person with a heavy accent was like an English teacher trying to teach Spanish with a strong lisp - not good.

I know from scrolling through threads Dosy is not popular, sounds like the Hi-Point of equipment. It was a good deal when I got it back in the late 90's, figured it was at least a good reference point. I am constantly looking for a budget oscilloscope, but I do have a CJ5 as my DD, and if you know anything about Jeeps..... Just Empty Every Pocket, those 'inexpensive' mods are anything but, and my CB budget is secondary...

If I was to just do a basic 1969 swap, pull old final, put in 1969, does it require any tweaking, as in frequency or alignment adjustments? I'm just looking for simple quick power - I have no safe place for a linear, as I don't want to risk water leaks in my CJ on trails. I know I won't get max power, but anything and opening up the modulation a bit (not going to disable the AMC in it) and I'll be happy. I could do other simple parts swaps too, as long as it doesn't mess up the frequency side of things.... Modulation and power are all I need to improve.

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A 100 watt or even a 50 will make a big difference. Not only will it amplify your signal but, audio too. There small (very small) easy to install and cheap ($$50-$100) on eBay. Good luck. 73.

well Cutlass, unless you already have a real 2SC1969, you are going to pay upwards of 25 bucks for one. don't even bother with ebay. all fakes.

the RFX75 advice is the best advice for your situation, and it's only 10 more dollars than the 1969.
adding this will make a real difference in your signal.

if you want to do the mod just because you find this type of thing fun, that's one thing, but if you are doing it because you are expecting to see a difference in your coverage area, you are going to end up disappointed.

the rule is that you need to increase your TX power by a factor of 4, in order to increase your signal by 1 s-unit in someone's radio.
that holds true whether you are talking about 1 watt, or 1000 watts.

so if your radio puts out about 20 watts PEP right now, (most 25's should do this with just a tune up) then increasing your output to 50 watts PEP is only going to gain you 1/2 an s-unit increase in a listener's radio. (another thing is that these mods are not "plug and play" situations. every radio is different, and you may need some tweaking of parts values in order to get it to work in your radio. when these mods get posted, many people think that they should be able to follow the instructions and make it work. but unless you have the knowledge to make it work, it's not always a good idea to try them on your radio)

LC

Modify modulation only if you have a scope and know how to use it. The meters that allegedly read modulation are quite frequently wrong and need calibration. If you want a little extra power put a KL-203 behind the radio. Don't even bother with the KL-203-P version. The -P is only a noise amplifier and have never seen one do any good.
It is not tuned input and is not the least bit selective in what get amplified. If you get the KL-203 keep your dead key wattage below 2.5 to three watts into a resistive load. The KL-203 is very sensitive to input overload and will smoke right out.
Doing the simple "Tune up" is a bad idea because the harmonics get excessive real quick and interfere with some of the ham radio bands.

2 "pill" amp with 1446, 2290 or 2879 Toshiba transistors (and a 20 amp DC power supply on a base station if you have a decent antenna) will get you heard. See 'em all the time on fleaBay and Craigs list. Usually around a Benjamin or so for those amps.

I would steer clear of the little Italian amps as all the folks I know that try to run them have RF feedback issues.

BBB said:

I would steer clear of the little Italian amps as all the folks I know that try to run them have RF feedback issues.

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I know the AD-203 has had that problem but have not the KL-203.
The AD-203 is installed inside the radio. If all of your jumpers are in good condition there should not be a problem. But the amps from Italy are pretty much throw away if they break down.
I do like the RFX line of amps that hang on the back of the radios.

Cutlass327 said:

Yeah, I plan to get one of those too, I figure swapping the final may be a bit more, but going to try the driver too. What all can I do of the steps Moleculo posted in this thread without affecting frequency? I plan to eventually get a good freq counter, so I can do it all, but in the mean time, I only want to mess with the power side. I do have a oscilloscope, but no freq counter yet....

The link I'm talking to:

http://www.worldwidedx.com/threads/cobra-29-high-power-mod-with-2sc1969-transistor.31449/

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I seem to be unable to find that thread...

But I did find this...

https://www.worldwidedx.com/threads...tc-any-high-level-tx.86832/page-4#post-254578

Just some clarification...

The above mod circuit was - and works - by "swamping" the Audio signal that has more of the AC component than DC - AFTER it passes thru that diode.

By utilizing that tap point, you obtain Phase Modulation - similar in effect to FM - because of it's negative voltage components - it can damage any amplifier that uses a single ended supply.

In that thread, I just posted a link for, Toll-Free discusses an important aspect of the mod he shows as 3 diodes, along with two resistors and a capacitor.

If any of you have followed the "ANL" research thread regarding the use of the ANL cap and why it's oriented like it is, you have to understand the effects of "lag effort" when it comes to this phenomenon Toll Free is discussing. I looking at the replies, the audio phase aspect is never discussed.

D1 thru the use of the Resistor R1 - taps into a reserve that the capacitor C1 can supply to a given point.

As long as the DC aspect of the Audio Transformer output is kept, and the Feeder Resistor R2 is allowed to pass into C1 to charge it - balance of multiplication of voltage can be sustained if only brief periods of time.

When you think of this - look into the AM Regulator Pass Transistor and the Voltage Regulation circuit used in it - there are similarities.

By utilizing that tap point - the output of the Modulation Transformer, you obtain Phase Modulation - similar in effect, to FM as it contains the frequency components in both Positive and Negative shift above and below 0 volt lines.

If D2 in the second circuit, is removed, the circuit performs similarly to the NPC mod done for the AM Regulator style radios.

Thanks for not throwing me off the cliff when I joined up here...

Usually when someone posts on a thread this old, Kopcicle will shows up with his video of a half-dead, zombie, merman (not mermaid) -looking crawling thing.
You got off lucky, Andy.

Careful, the nights still young...

But just to sidebar, before the "Zombies arrive"

Ok, never mind that...ahemn...

I was working on something I found using an older 538W that I thought would kinda be neat to tell others.

It was buried in a thread called Asymmetrical Mods on the CB Tricks days...

Sigh...oh well, I had posted a similar circuit from the ARRL website to the one above as a "methodology" to help understand the non-symmetrical effects of the negative components and how using Transformer design versus the AM Regulator - the voltage component obtained - oftentimes gets lost and underutilized. Even misunderstood - which I am too - just like those....

The Transformer - as discussed in a previous thread... that part of the conversation was interesting - it may be worth reviewing because of a link I found in there from @500kpot that fits with the "Tube philosophy" in using similar methods

Either way, the whole purpose of the post was to help locate a missing thread I've love to read - but can't locate via the links provided - I'm not sure if it was deleted or removed or relocated to - who knows where?