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I'd just pony up for the 2166 & 1969s and never let anyone borrow it again. Haha. I have a first gen Deltaforce and I really enjoy it. The parts are packed pretty tight in the final section of these rigs, and while very similar to an RCI final section, it's a bit different. In the end you'll be...

If I've done my math correctly, it happens sometimes, the 125% that commercial stations use for speech broadcasts is just a curly blonde one over a 5:1 (123.6%, I think) ratio. As Captain Kilowatt pointed out though, the negative peaks must not be allowed to pinch off. The positive ones...

Not a fan of that top gun modulator. In stock form mine was "loud" and it made the meter bounce around a bunch, but it got out, and sounded, much better with it removed. Back on topic... What's the point of a 40:1 ratio though? If a radio is capable of 80W PEP on AM, then it should be capable...

None that I know of. I honestly wouldn't see the point. I have yet to hear a _clean_ signal on air with a modulation percentage higher than what a standard diode detector can handle. Most detectors, that I've seen, start distorting between 105% to 125%. Most (damn near all) of the, "big...

Lots of good stuff in here from everyone. Really digging this thread. I wish more people knew these kinds of things, it would make my ears a lot happier. My local area has some real wild sounding stuff on the air. My favorite response to people, that I hear locally, that try to say that higher...

I'd just stick with a standard 4:1 PEP to Carrier ratio and leave it at that. Good clear audio, clean RF, and a good antenna system will easily get you heard. There are some specific reasons to use a different ratio but unless you have one of those reasons, I'd stick to the normal. Any standard...

You are correct in that the SWR becomes flat due to the resistive input pad. This doesn't actually fix the problem of power being reflected from the input though, and the pad/attenuator is just absorbing the reflected power, in the same way it absorbs some of the input power, so it's not making...

I could be wrong here, but it appears that the safety switch that prevents operation with the lid removed is disconnected.

The two original ones in my IC-751 (non-A) have held up great. I wouldn't say that I've abused them, but I have put them in some less than ideal situations by accident and they could easily exceed the radio's rated 100W output when the ALC op-amp decided to give up. The previous owner daily...

My obsessive tendencies are both a blessing and a curse. While the projects that I label as "finished" are always overkill in the details department, they also seem to take infinitely longer to construct. What most people could do in a weekend usually takes me a month or two worth of weekends...

I've never put the ERF2030+ in an N2/98VHP amp unit, but I have installed them into a Connex 4400 Turbo amp unit which is just half the size. It uses 4 FETs versus 8. I can tell you one thing that is absolutely a fact; they are NOT just a drop in replacement. The ERF2030+ FETs have a much higher...

50E should be 50 Volts. 2R2 should make it a 2.2uF. The black stripe indicates the negative terminal.

Watch the intermodulation distortion products above and below your modulation and/or fundamental as well.

If the bias current is greater than 0mA it's technically Class-AB, around 50mA is a typical setting, although sometimes a bit more is required. You can't really see the conduction angle on the scope due to LC part of the circuit providing the rest of the wave while the Mosfet is off. You can do...

Not exactly. The older bipolar radios had what we called a mirror board in front of the finals. This board connected the regulator's output (TP9) to the driver (TP8) and final stages (TP7). To set the biasing on those radios, you simply pulled the mirror board out (it was a pressure fit) and...

I think we found the disconnect between what you have on your bench and the papers I'm looking at here. That board is a Ranger/RCI board, and from what I'm told, this is the correct schematic here. http://www.cbtricks.com/radios/rci/tr_296gk_dx/graphics/tr_296gk_dx_sm_sch.pdf On this board...

Of course they are different chips with different specs. They are still both Gilbert cell double balanced mixers and when it comes to the DIP14 package, they have the same pin out as far as I can tell, since I can only find the SMD data for the 6130. Your picture you posted of the bottom of the...

I don't see an R212 on my schematic. It's an old one, but it shows R191 directly between pin 8 of IC4 and the anode of D53. I'm not familiar with all of the differences in the different 148s. If you look at the schematic though, the 7.8MHz signal comes from pin 7 of the balanced modulator (just...

I like to run my IRF520s at ~50mA per device, but it depends upon the application. In the 4400 Turbo amp (has half of the 98VHP amp) ~50mA gave me the best linearity and the cleanest signal out of the amplifier with the stock 520s. They weren't matched at the factory and I gained a couple db...

Andy, your explanation of those 2 resistors and the image of the IC internals is 100% completely wrong. Please read the datasheets of these devices. https://www.cbtricks.com/radios/galaxy/datasheets/ic/pdf/s042p.pdf The S042P and the TDA6130 (in the DIP package, SMD has a different pin out)...