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Discussion in 'General CB Services Discussion' started by Low_Boy, May 5, 2018.
A NEW HACK I never saw until today.
Is that part of a swing mod?
No, not swing, ripple filter. The Emitter and Collector - offset by a cap - DC arrives in and audio + DC passes out.
Wiki has got some help to it
Why? It's used to smooth harsh ringing effects from switching noises - ripple to remove noise (judging by cap values) about 2kHz and higher - to DC - it's like using a cap to shunt to ground - you can do the same thing but make it to the plus rail (Battery DC)
:+> Andy <+:
I removed it. Do you think it should go back. The radio had all kind of swing mods that I removed. I do not have to ask if I should put them back. LOL
If it doesn't affect your tone or maybe you like the tone now, all it was, or functions as, a high-cut smoothing filter - kinda' takes the high end (upper audible range) "Snaps" that may occur during switching loads - rounds off their "edge" into a curve. Much like ANL filter caps.
You'd be better off swapping that out - the Mylars are common, but not indestructible. Considering their construction - can be subject to damage from vibration, pressure/stress and they use "aluminized paper" a lot like the Electrolytics do, only without the electrolytic (no galvanic effects) - the size of it - I guess the value to be between 0.22uf (224) or 0.1uF (104) these are not polarized so they can be swapped with ceramic discs if you have spacing issues.
:+> Andy <+:
I think its to make the modulation more clear.
It is not my radio it belongs to someone I work with. Radio had all kind of problems I just straightened it out for him. I nerver ran with him but the other drivers said it sounded bad most of the time. I think it sounds pretty good now. Now I can get back to working on my cobra 29.
Don't know the value if the green capacitor, but if you listen to this radio's transmit audio on another radio, you can decide if it changes the sound for better or worse.
Pretty sure all it should do is reduce the treble response.
Maybe enough to hear the difference, maybe not.
The factory puts a 0.1uf (104) capacitor (C212) on the top side of the pc board across the same spot. If it has been removed, you might want to leave this one where it is.
I use a stock radio with no antenna to listen to the on air sound of a radio I have repaired. No amount of rf sampling matters if it does not sound good on the rx end of a stock radio for me. I know that is ultra low tech and not at all empirical since it does not generate a number or other such measurement that I can correlate and record. Although ultimately since we listen to the radio with our ears it is a valid validation process once you think you have all your ducks in a row. Kind of like shooting a rifle versus looking at it's barrel with a borescope. Ultimately the true test is in the shooting of the rifle not how pretty the bore might look!
Put another way I have seen some beautiful trumpets that played like dogs! Audio amps that looked great on test gear but sounded terrible! Sometimes the practical is more important than appearances or less than dynamic test conditions! We do at times get caught up in the technical and we forgot about the practical basis of our hobby!
When it comes to modifications one well thought out and a well-executed mod can be worth far more than many poorly done modifications. Often times more is not better with a good many things. The prob. is that just because someone can hold a soldering iron and put parts on a board does not mean they understand what they are doing and why! Without understanding no matter how well the parts are placed on the board and joined to the rest of the circuit the end result will seldom be anything of value unless it happens by happy accident! LOL If one does not have the gear to see the results of ones work how can you predict and repeatedly get the result you want?
If I ever get some time I will experiment with this on one of my radios. That radio belonged to someone I work with and I gave it back already. That radio will probably never sound good lol. Way too many hacks have been in it. But atleast now it is working and the modulation looks a bit better.