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Why not just bypass all the lytic audio decoupling caps with film caps

O

Onelasttime

Sr. Member
Aug 3, 2011
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Seems like it would be super easy to bypass all the lytics in the audio section of a CB radio. You could prob. do it on the back side of the board if their is not enough space on the component side. The ceramics could be replaced as well if they need it. Obviously every cap in the audio section does not need such treatment. When I got to thinking about how I would just bypass a lytic with a film if this was in an audio setting and I about slapped myself for not just doing that in a CB. If the caps are good and your not recapping why not just bypass the lytic in question with a film cap of your choice. Theory wise a film 20% of the lytic might work to bypass it. That said the closer to being able to do the job with out the lytic you can get the better the outcome should be. Just theory though. It freq. works in home audio gear and electrons are electrons and almost always behave in repeatable ways so the fact that this is a CB and not an eq or mixer or pa should not matter that much.

Any devils advocates that think this is a terrible idea? I would never do this in an old unit that might need to be recapped since this might hide or mask the symptoms of a bad cap. A bad cap can behave like a resistor or diode and really cause problems.
 

bypassing any cheap electrolytic coupling caps with something like .1 - .47uf wimas may add a wee bit of smooth & sparkle to the upper mid & trebble of the audio leaving the mic preamp but hearing it over the air i don't know, try it,

don't know how you would do a blind test without two of the same rigs aligned the same and a helper to swap em,

if you can identify the modded rig 10x out of 10 or more in a blind test even when your helper trys hard to trip you up, the odds are its not your imagination,
if you can't then it is your imagination.
 
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If a capacitor is leaky bypassing it with another cap will not help at all. The leaky capacitor can off set bias and/or eventually cause a DC short. There are reasons why there are so many different types of capacitors. All of them have strengths and weaknesses. Electrolytic capacitors can pack a huge amount of capacitance in a small place. Tantalum, the same but limited high voltage ratings. And neither of those can handle a large amount of AC power. The OIL FILLED caps like those used in motor starter circuits can handle power but are too large for most circuit boards used in our type of electronics. Effective Series Resistance (ESR) is a consideration in many circuits.
 
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bob85 said:
bypassing any cheap electrolytic coupling caps with something like .1 - .47uf wimas may add a wee bit of smooth & sparkle to the upper mid & trebble of the audio leaving the mic preamp but hearing it over the air i don't know, try it,

don't know how you would do a blind test without two of the same rigs aligned the same and a helper to swap em,

if you can identify the modded rig 10x out of 10 or more in a blind test even when your helper trys hard to trip you up, the odds are its not your imagination,
if you can't then it is your imagination.
Click to expand...
Used some wimas caps in the audio circuit of a Cobra 148 before with outstanding results as per the Goldfinger mod.

Use that radio as a loner radio while fixing/aligning some locals radio.
They seem to rave on about the audio receive.
 
Robb
Back in the late 80's early 90's i modded & aligned a scruffy lincoln for wider tx & rx with wimas,
me and a buddy went up a hill to compare his like new aligned by him lincoln against my scruffy aligned & modded by me example on TX & RX,

after about 1 hour he was totally convinced that his radio was faulty and offerd me £50 and his rig for mine even though i explained that it was the caps and i could mod his to sound the same,

He was an electronics service engineer working for phillips and into hifi,
i could not convince him that his rig was perfectly normal and the difference was just the caps i had swapped in the audio stages ;).
 
I was just at working and thinking about a cheap, quick dirty way for people with otherwise new radio's to maybe enhance the audio. You know a kid a buys or owns a relatively new radio that does not need to be recapped due to age wtc....I was thinking it might make enhanced audio quality a bit more accessible to some.

Not everyone wants to direct inject. I talk 99% on SSB and I have no desire to do the MMM which is not for sale any more is it? I likewise do not want to direct inject on AM.

In a million yours you would not see me wanting to do 200%, 300% modulation etc....

In fact even if I decided to play around with asymetric modulation and such I doubt you would ever see me actually broadcast with more than 110%-120% even as a novelty. I doubt most receiving units could benefit from it at all so why waste my audio and rf energy for that type of envelope if it will not benefit me.

That said the sound quality on transmit and receive in CB and Export world really is pathetic and could use a little bit of improvement.

It is a lot like other things. While I as person benefit from increases my strength and muscle mass over what it is I would not benefit from being able to squat 1000lbs. or being as muscular as a bodybuilder. Likewise I can always use some cardiovascular improvements I would never benefit from being able to run a Marathon and finish in say 2 hours and 35 minutes. I would benefit from being a bit more flexible but I doubt being able to do the splits would benefit me that much. I am not about extreme's I am a bout margin of return on investment and being good at a lot of things not an expert at just one thing! I am not one to say things like "extremes are for loser's" or anything like that but focusing on one extreme aspect of performance seldom pays off in any real returns that are tangible. If it is a car and you intend to use it in real life the ability to turn the car at speed well and the ability to stop the car reliably at speed are just as important as top end or acceleration etc.....

If I do decide to give direct injection a go I already know it would not be my daily use radio and I would not use it often. It would be a novelty. I have a friend that owns a 10,000 watt AM broadcast transmitter. I can count on one hand how many times he has turned it on and used it at capacity in the last 23 years that I have known him.

DI and MMM and Asymod are all very very wasteful methods of producing AM signal. Dollar per watt is crazy and all the gear used is again crazy. It makes no sense if looked at from a logical stand point. It would be about as silly as driving a 3000+HP Nitro car on the road or as your daily driver! LOL

I would rather talk to a guy in England about Brexit at 3am EST on SSB with 50 watts than talk to Billy Bob 3 States away on Channel 6 AM with 5000 watts and 240% modulation just long enough to rattle off my station identifier. I am not really the QSL card type I like to actually talk to people on a channel. Once in a while you might catch contesting but not that often. Never really understood why someone would want to talk to someone just long enough to get your station identifiers heard then move on. I guess I like people too much. I do not want to tell someone my name then move on tot he next person and the next and the next in real life so why do not on radio. Then again EME and slow scan TV never made sense to me either but it takes all kinds to keep like interesting and fun! I love to Mountain Climb but never wanted to climb Everest of K2.

If I can hear them I want to talk to them and if they can hear me I want to hear them.
 

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