|
|
Post by Night Ranger on Aug 3, 2014 9:49:56 GMT -5
Step right up suckers! CB snake oil ready for purchase on Ebay! www.ebay.com/itm/New-CB-Coax-Routing-Board-Proven-Workability-Improve-SWRs-And-Reception-/281402550268?pt=US_CB_Radios&hash=item4184e627fcThe ad states.... =========================================== Made Exclusively By Gentry's Auto & Electronics. Improve Reception Improve SWR's Get 100% Straight Line Polarity From You Coax As It Is Intended To Work , All I Repeat All Mobile Radios In Cars Trucks Semis should Be Using At Liest 18FT of Coax - This Is A Given ! Any Thing Less Will Provide You With High SWR Ratings and A Loss Of Reception And TX Ability , Today's High Power Radio's Will only Survive The Long Run] With The Proper Coax Installments .... Over The Years Drivers Come In And Show Me Their Set Ups In The Rigs , Or I Will Adjust Antennas , SWR's and The Most Given Reason Of Poor Reception is 1) Bad Coax 2) Not The Proper Length 3) Extra Coax - Rolled or Shoved in To Cubby Holes , Pushed Under The Vehicle Seating - THE BIG NO NO !! In Order To Receive And Broadcast Correctly Mobile Radios Need At Liest 18ft Of Coax - This Assures Easy Set SWR's & 18ft of Coax means 18 ft Straight Line Coax - Ask Your self This Question , What Good Does 18 Ft Of Coax Do If It's All Rolled In To a Neat Circle Coil or Shoved Under Your Seat - The Answer Is , You are Most likely Shorting Your Self That Extra 7 to 10 Foot of Coax - You Might as Well Just Use 8 FT Of Coax and Over Time Get Used To Poor reception and The Ability to Properly Talk To You Friends / Co Workers , If Your Satisfied With a 1 Mile Of Communication Than This Is Not For You !!! I'm Here To Help The Professionals Who Depend On Open Communication for Road Reports , Bear Reports , Weather ,Accident Reports , Road Conditions, Or Just To Keep Company With A Fellow Driver . Over The Years I Have Made A Few Hundred Of These And They Have always Helped With Reception , SWR Control, And TX & RX . These Are Only Made For The Public By Gentry's Auto & Electronics Get Yours Today And Get Your Talk On The Air For Extended Miles ..... Improved Reception Up To 30% And Add On To The Miles Your Able To Broad Cast . Bundled Coax Cause Shorts , Poor SWR's , Incorrect Wattage Out Put TX and Bad RX , Resulting in Burned Finals and Drivers ......... Most CB Radio's Are A Good Size Investment ! Protect Yours And Enjoy It The Way It Was Meant To Be .............. Thanks For Looking ! TC Gentry Thanks For Looking @ Our Auctions Gentry's Auto & Electronics TC Gentry ================================ Night Ranger |
|
Sandbagger
Administrator/The Boss 
Posts: 6,250 
|
Post by Sandbagger on Aug 3, 2014 11:28:40 GMT -5
Step right up suckers! CB snake oil ready for purchase on Ebay! www.ebay.com/itm/New-CB-Coax-Routing-Board-Proven-Workability-Improve-SWRs-And-Reception-/281402550268?pt=US_CB_Radios&hash=item4184e627fcThe ad states.... =========================================== Made Exclusively By Gentry's Auto & Electronics. Improve Reception Improve SWR's Get 100% Straight Line Polarity From You Coax As It Is Intended To Work , All I Repeat All Mobile Radios In Cars Trucks Semis should Be Using At Liest 18FT of Coax - This Is A Given ! Any Thing Less Will Provide You With High SWR Ratings and A Loss Of Reception And TX Ability , Today's High Power Radio's Will only Survive The Long Run] With The Proper Coax Installments .... Over The Years Drivers Come In And Show Me Their Set Ups In The Rigs , Or I Will Adjust Antennas , SWR's and The Most Given Reason Of Poor Reception is 1) Bad Coax 2) Not The Proper Length 3) Extra Coax - Rolled or Shoved in To Cubby Holes , Pushed Under The Vehicle Seating - THE BIG NO NO !! In Order To Receive And Broadcast Correctly Mobile Radios Need At Liest 18ft Of Coax - This Assures Easy Set SWR's & 18ft of Coax means 18 ft Straight Line Coax - Ask Your self This Question , What Good Does 18 Ft Of Coax Do If It's All Rolled In To a Neat Circle Coil or Shoved Under Your Seat - The Answer Is , You are Most likely Shorting Your Self That Extra 7 to 10 Foot of Coax - You Might as Well Just Use 8 FT Of Coax and Over Time Get Used To Poor reception and The Ability to Properly Talk To You Friends / Co Workers , If Your Satisfied With a 1 Mile Of Communication Than This Is Not For You !!! I'm Here To Help The Professionals Who Depend On Open Communication for Road Reports , Bear Reports , Weather ,Accident Reports , Road Conditions, Or Just To Keep Company With A Fellow Driver . Over The Years I Have Made A Few Hundred Of These And They Have always Helped With Reception , SWR Control, And TX & RX . These Are Only Made For The Public By Gentry's Auto & Electronics Get Yours Today And Get Your Talk On The Air For Extended Miles ..... Improved Reception Up To 30% And Add On To The Miles Your Able To Broad Cast . Bundled Coax Cause Shorts , Poor SWR's , Incorrect Wattage Out Put TX and Bad RX , Resulting in Burned Finals and Drivers ......... Most CB Radio's Are A Good Size Investment ! Protect Yours And Enjoy It The Way It Was Meant To Be .............. Thanks For Looking ! TC Gentry Thanks For Looking @ Our Auctions Gentry's Auto & Electronics TC Gentry ================================ Night Ranger What a maroon....... SWR is not a function of feedline length. And if they want to use that whole optimal feedline length idea, then they need to consider the velocity factor of the cable, which makes the optimal length to be about 12'. Snake oil.... coming to a channel near you. |
|
|
|
Post by Night Ranger on Aug 3, 2014 12:09:33 GMT -5
|
|
Sandbagger
Administrator/The Boss
Posts: 6,250
|
Post by Sandbagger on Aug 3, 2014 12:38:25 GMT -5
Wow, a 900 Mhz stacked Gizmotchy? That is truly a joke...... |
|
|
|
Post by MonkeyMan on Aug 3, 2014 15:20:47 GMT -5
The ad states.... =========================================== Made Exclusively By Gentry's Auto & Electronics. Improve Reception Improve SWR's Get 100% Straight Line Polarity From You Coax As It Is Intended To Work , All I Repeat All Mobile Radios In Cars Trucks Semis should Be Using At Liest 18FT of Coax I wouldn't buy anything from a guy who can't spell basic words and/or use spell check. FAIL.  |
|
|
|
Post by Night Ranger on Aug 3, 2014 18:12:46 GMT -5
What a maroon....... SWR is not a function of feedline length. And if they want to use that whole optimal feedline length idea, then they need to consider the velocity factor of the cable, which makes the optimal length to be about 12'. Snake oil.... coming to a channel near you. What the heck is "Straight Line Polarity"? As opposed to what? Crooked line polarity? Heaven forbid! : ) You know, what he may be doing without realizing it is creating an RF coxial choke when he coils up the coax. If the increased impedance is high enough it could attenuate rf currents flowing on the outside of the coax from the antenna, and that might affect the reading on an SWR meter between the RF choke and the radio. Of course he could accomplish the same thing by coiling the coax around a ferrite choke at the base of the antenna or snapping on several ferrite beads around the coax at the antenna. Build an All Band HF Air Core 1:1 Choke Balun www.hamuniverse.com/balun.htmlNight Ranger |
|
Sandbagger
Administrator/The Boss
Posts: 6,250
|
Post by Sandbagger on Aug 4, 2014 6:08:01 GMT -5
What a maroon....... SWR is not a function of feedline length. And if they want to use that whole optimal feedline length idea, then they need to consider the velocity factor of the cable, which makes the optimal length to be about 12'. Snake oil.... coming to a channel near you. What the heck is "Straight Line Polarity"? As opposed to what? Crooked line polarity? Heaven forbid! : ) You know, what he may be doing without realizing it is creating an RF coxial choke when he coils up the coax. If the increased impedance is high enough it could attenuate rf currents flowing on the outside of the coax from the antenna, and that might affect the reading on an SWR meter between the RF choke and the radio. Of course he could accomplish the same thing by coiling the coax around a ferrite choke at the base of the antenna or snapping on several ferrite beads around the coax at the antenna. Build an All Band HF Air Core 1:1 Choke Balun www.hamuniverse.com/balun.htmlNight Ranger That's a good point, it is essentially an RF choke, similar to what we make to reduce common mode RF currents on the shield of the coax as a result of using "radial-less" stick antennas like the A99. A choke like that would help reduce RF feedback (mic squeals), and potential for stray RF getting into the car's electrical system, but it isn't going to "fix" an SWR problem, that is contained within the antenna. "Straight line polarity" another vague CB science term, right up there with "modulation gain" which Jo-Gunn uses for their antennas. |
|
|
|
Post by Night Ranger on Aug 4, 2014 7:19:54 GMT -5
What the heck is "Straight Line Polarity"? As opposed to what? Crooked line polarity? Heaven forbid! : ) You know, what he may be doing without realizing it is creating an RF coxial choke when he coils up the coax. If the increased impedance is high enough it could attenuate rf currents flowing on the outside of the coax from the antenna, and that might affect the reading on an SWR meter between the RF choke and the radio. Of course he could accomplish the same thing by coiling the coax around a ferrite choke at the base of the antenna or snapping on several ferrite beads around the coax at the antenna. Build an All Band HF Air Core 1:1 Choke Balun www.hamuniverse.com/balun.htmlNight Ranger That's a good point, it is essentially an RF choke, similar to what we make to reduce common mode RF currents on the shield of the coax as a result of using "radial-less" stick antennas like the A99. A choke like that would help reduce RF feedback (mic squeals), and potential for stray RF getting into the car's electrical system, but it isn't going to "fix" an SWR problem, that is contained within the antenna. "Straight line polarity" another vague CB science term, right up there with "modulation gain" which Jo-Gunn uses for their antennas. I've tried my best to kill the whole "CB AM swing" nonsense among the locals, but it's like trying to teach calculus to a monkey. One of the locals is an avid transistor amp builder. He told me he is an engineer, but after hearing him repeatedly talk about how much his amps "swing" I have to ask myself; "An engineer of what?". His wattage claims far exceed the Toshiba 2sc2879a datasheet. He once commented how my tube type Robyn T-123b and my tube type D&A Maverick had almost no swing, and he said the difference was because I was using tubes instead of transistors. I wondered if he went to the Ray Felt's school of CB Engineering Nonsense*. Nice guy though, and he does build alot of transistor amps. *Ray Felts built the Elkin CB amps. Night Ranger |
|
|
|
Post by KneeBiter on Aug 4, 2014 7:43:01 GMT -5
Shaaa Winggggggggg !
|
|
Sandbagger
Administrator/The Boss
Posts: 6,250
|
Post by Sandbagger on Aug 4, 2014 9:02:33 GMT -5
That's a good point, it is essentially an RF choke, similar to what we make to reduce common mode RF currents on the shield of the coax as a result of using "radial-less" stick antennas like the A99. A choke like that would help reduce RF feedback (mic squeals), and potential for stray RF getting into the car's electrical system, but it isn't going to "fix" an SWR problem, that is contained within the antenna. "Straight line polarity" another vague CB science term, right up there with "modulation gain" which Jo-Gunn uses for their antennas. I've tried my best to kill the whole "CB AM swing" nonsense among the locals, but it's like trying to teach calculus to a monkey. One of the locals is an avid transistor amp builder. He told me he is an engineer, but after hearing him repeatedly talk about how much his amps "swing" I have to ask myself; "An engineer of what?". His wattage claims far exceed the Toshiba 2sc2879a datasheet. He once commented how my tube type Robyn T-123b and my tube type D&A Maverick had almost no swing, and he said the difference was because I was using tubes instead of transistors. I wondered if he went to the Ray Felt's school of CB Engineering Nonsense*. Nice guy though, and he does build alot of transistor amps. *Ray Felts built the Elkin CB amps. Night Ranger You should probably cut him a little slack. While the term "swing" makes the hair on the back necks of engineers bristle, there is some validity to running asymmetrical modulation or controlled carrier modulation. Either technique can result in a greater than 4:1 positive peak to carrier ratio, and a forward "swing" on an average reading watt meter. And there is a noticeable increase in the loudness for those who employ those techniques. The only problem is that most CB hack shops do it the easy way which results in all sorts of splatter via negative peak cutoff. But if you can do a decent NPC mod, and keep the negative peak from sharply cutting off, you can get a forward "swing" without splattering across the band. Of course, a lot of people subscribe to the "If a little is good, a lot must be better" theory, and they tend to overdo it. It's insanity to dead key 10 watts and "swing" to 500. If you want that much "swing", try running SSB. But a 6:1 or 8:1 peak:carrier ratio is doable and sounds pretty good if done right. But the "tubes" comment gets the thumbs down. There is no technique in an amplifier that you can do with transistors that you can't do with tubes. So many people do not understand tubes.....  |
|
|
|
Post by Night Ranger on Aug 4, 2014 9:20:43 GMT -5
I've tried my best to kill the whole "CB AM swing" nonsense among the locals, but it's like trying to teach calculus to a monkey. One of the locals is an avid transistor amp builder. He told me he is an engineer, but after hearing him repeatedly talk about how much his amps "swing" I have to ask myself; "An engineer of what?". His wattage claims far exceed the Toshiba 2sc2879a datasheet. He once commented how my tube type Robyn T-123b and my tube type D&A Maverick had almost no swing, and he said the difference was because I was using tubes instead of transistors. I wondered if he went to the Ray Felt's school of CB Engineering Nonsense*. Nice guy though, and he does build alot of transistor amps. *Ray Felts built the Elkin CB amps. Night Ranger You should probably cut him a little slack. While the term "swing" makes the hair on the back necks of engineers bristle, there is some validity to running asymmetrical modulation or controlled carrier modulation. Either technique can result in a greater than 4:1 positive peak to carrier ratio, and a forward "swing" on an average reading watt meter. And there is a noticeable increase in the loudness for those who employ those techniques. The only problem is that most CB hack shops do it the easy way which results in all sorts of splatter via negative peak cutoff. But if you can do a decent NPC mod, and keep the negative peak from sharply cutting off, you can get a forward "swing" without splattering across the band. Of course, a lot of people subscribe to the "If a little is good, a lot must be better" theory, and they tend to overdo it. It's insanity to dead key 10 watts and "swing" to 500. If you want that much "swing", try running SSB. But a 6:1 or 8:1 peak:carrier ratio is doable and sounds pretty good if done right. But the "tubes" comment gets the thumbs down. There is no technique in an amplifier that you can do with transistors that you can't do with tubes. So many people do not understand tubes..... He said he did not want to have anything to do with tubes although I don't understand the prejudice. They are different and yet similar. I find them both interesting. I explained that with the rising price of 2sc2879a transistors that tubes could actually be alot cheaper per watt depending on the tube (6km6 - $7 to $12 each, 22jg6a - $3 to $12 each) versus 2sc2879a ($40 each at rfparts.com). I also mentioned that for high power it was simpler to wire up one big tube than 24 or 32 2sc2879a transistors. As far as "asymmetrical modulation or controlled carrier modulation", I don't think he is doing anything that advanced. From the pictures I have seen of his amps they look like the typical silver boxed 2sc2879a competition amps. I did not see anything inside them to indicate additional circuity to do what you are referring to. Night Ranger |
|
Sandbagger
Administrator/The Boss
Posts: 6,250
|
Post by Sandbagger on Aug 4, 2014 13:47:40 GMT -5
You should probably cut him a little slack. While the term "swing" makes the hair on the back necks of engineers bristle, there is some validity to running asymmetrical modulation or controlled carrier modulation. Either technique can result in a greater than 4:1 positive peak to carrier ratio, and a forward "swing" on an average reading watt meter. And there is a noticeable increase in the loudness for those who employ those techniques. The only problem is that most CB hack shops do it the easy way which results in all sorts of splatter via negative peak cutoff. But if you can do a decent NPC mod, and keep the negative peak from sharply cutting off, you can get a forward "swing" without splattering across the band. Of course, a lot of people subscribe to the "If a little is good, a lot must be better" theory, and they tend to overdo it. It's insanity to dead key 10 watts and "swing" to 500. If you want that much "swing", try running SSB. But a 6:1 or 8:1 peak:carrier ratio is doable and sounds pretty good if done right. But the "tubes" comment gets the thumbs down. There is no technique in an amplifier that you can do with transistors that you can't do with tubes. So many people do not understand tubes..... He said he did not want to have anything to do with tubes although I don't understand the prejudice. They are different and yet similar. I find them both interesting. I explained that with the rising price of 2sc2879a transistors that tubes could actually be alot cheaper per watt depending on the tube (6km6 - $7 to $12 each, 22jg6a - $3 to $12 each) versus 2sc2879a ($40 each at rfparts.com). I also mentioned that for high power it was simpler to wire up one big tube than 24 or 32 2sc2879a transistors. As far as "asymmetrical modulation or controlled carrier modulation", I don't think he is doing anything that advanced. From the pictures I have seen of his amps they look like the typical silver boxed 2sc2879a competition amps. I did not see anything inside them to indicate additional circuity to do what you are referring to. Night Ranger No, most guys who "want nothing to do with tubes" either don't understand them, or are afraid of the high voltages present. As for Advanced modulation schemes, those are normally done in the exciter radios, not in the amplifier. A true linear amplifier will amplify what you put into it in near exact proportions, with no distortion. An amplifier that enhances "swing" does so by being decidedly NON-linear. In other words, a class "C" amp. These guys rely on the sharp cutoff "knee" of the transistor, to achieve a large change in output power over a very small drive level change. The problem with this is that below a certain minimum drive level, the output power drops right to zero, making for a negative modulation peak cutoff, and the resultant splatter and that typical "harsh" sould that accompanies someone running a class "C" amp in that "knee" area right above cutoff. Adding a little bias will correct this condition, but it defeats the purpose for those guys who want to see their wattmeters move strongly forward. The absolute worst is a "swing mod" modified and clipped radio, running into a class "C" amp. Guaranteed distortion. Of course you could achieve the same thing with tubes, but most CB sweep tube amps are driven in a grounded grid configuration which self biases it above a class "C" region (usually class B), so they can't get the same "swing" effect from it. You would have to build a negative voltage supply, lift the control grid from ground, and apply enough negative bias voltage to force class "C" operation. That's probably not worth the time for the average CB amp builder. |
|
|
|
Post by Night Ranger on Aug 4, 2014 14:13:58 GMT -5
He said he did not want to have anything to do with tubes although I don't understand the prejudice. They are different and yet similar. I find them both interesting. I explained that with the rising price of 2sc2879a transistors that tubes could actually be alot cheaper per watt depending on the tube (6km6 - $7 to $12 each, 22jg6a - $3 to $12 each) versus 2sc2879a ($40 each at rfparts.com). I also mentioned that for high power it was simpler to wire up one big tube than 24 or 32 2sc2879a transistors. As far as "asymmetrical modulation or controlled carrier modulation", I don't think he is doing anything that advanced. From the pictures I have seen of his amps they look like the typical silver boxed 2sc2879a competition amps. I did not see anything inside them to indicate additional circuity to do what you are referring to. Night Ranger No, most guys who "want nothing to do with tubes" either don't understand them, or are afraid of the high voltages present. As for Advanced modulation schemes, those are normally done in the exciter radios, not in the amplifier. A true linear amplifier will amplify what you put into it in near exact proportions, with no distortion. An amplifier that enhances "swing" does so by being decidedly NON-linear. In other words, a class "C" amp. These guys rely on the sharp cutoff "knee" of the transistor, to achieve a large change in output power over a very small drive level change. The problem with this is that below a certain minimum drive level, the output power drops right to zero, making for a negative modulation peak cutoff, and the resultant splatter and that typical "harsh" sould that accompanies someone running a class "C" amp in that "knee" area right above cutoff. Adding a little bias will correct this condition, but it defeats the purpose for those guys who want to see their wattmeters move strongly forward. The absolute worst is a "swing mod" modified and clipped radio, running into a class "C" amp. Guaranteed distortion. Of course you could achieve the same thing with tubes, but most CB sweep tube amps are driven in a grounded grid configuration which self biases it above a class "C" region (usually class B), so they can't get the same "swing" effect from it. You would have to build a negative voltage supply, lift the control grid from ground, and apply enough negative bias voltage to force class "C" operation. That's probably not worth the time for the average CB amp builder. I understand the fear of high voltage. I'm afraid of 3cx3000a7 and higher amps for that very reason. I understand them, but the high voltage level makes me gun shy. I also understand not liking them due to not understanding them. I felt the same way about Phase Lock Loop (PLL) versus crystal synthesis until I read Lou Franklin's book "The CB PLL Databook". Now I think PLL and crystal synthesis are cool. My Drake 4 B-Line twins use controlled carrier AM. The "swing" is ridiculous, but the audio is surprisingly good. Night Ranger |
|
Sandbagger
Administrator/The Boss
Posts: 6,250
|
Post by Sandbagger on Aug 4, 2014 19:21:28 GMT -5
No, most guys who "want nothing to do with tubes" either don't understand them, or are afraid of the high voltages present. As for Advanced modulation schemes, those are normally done in the exciter radios, not in the amplifier. A true linear amplifier will amplify what you put into it in near exact proportions, with no distortion. An amplifier that enhances "swing" does so by being decidedly NON-linear. In other words, a class "C" amp. These guys rely on the sharp cutoff "knee" of the transistor, to achieve a large change in output power over a very small drive level change. The problem with this is that below a certain minimum drive level, the output power drops right to zero, making for a negative modulation peak cutoff, and the resultant splatter and that typical "harsh" sould that accompanies someone running a class "C" amp in that "knee" area right above cutoff. Adding a little bias will correct this condition, but it defeats the purpose for those guys who want to see their wattmeters move strongly forward. The absolute worst is a "swing mod" modified and clipped radio, running into a class "C" amp. Guaranteed distortion. Of course you could achieve the same thing with tubes, but most CB sweep tube amps are driven in a grounded grid configuration which self biases it above a class "C" region (usually class B), so they can't get the same "swing" effect from it. You would have to build a negative voltage supply, lift the control grid from ground, and apply enough negative bias voltage to force class "C" operation. That's probably not worth the time for the average CB amp builder. I understand the fear of high voltage. I'm afraid of 3cx3000a7 and higher amps for that very reason. I understand them, but the high voltage level makes me gun shy. I also understand not liking them due to not understanding them. I felt the same way about Phase Lock Loop (PLL) versus crystal synthesis until I read Lou Franklin's book "The CB PLL Databook". Now I think PLL and crystal synthesis are cool. My Drake 4 B-Line twins use controlled carrier AM. The "swing" is ridiculous, but the audio is surprisingly good. Night Ranger I'll let you in on a little secret, I'm comfortable playing with sweep tube amps, but those big boys with 3000 volts on the plate make me a bit nervous as well. Taking voltage readings is a bit tough, and I'm always afraid the probe will slip off and cause a shower of sparks...  My Icom has low level AM modulation as well. If you set the carrier level for 25 watts,it will give you a nice 4:1 ratio with 100 watts PEP. If I drop the carrier down, the PEP power remains at 100 watts, so the lower I drop the carrier, the more "swing" it has. The nice part is that it does not clip the negative peak, it's all forward, so it's not too shabby. But I never use the Icom on AM......  |
|
|
|
Post by BBB on Aug 5, 2014 9:52:51 GMT -5
Seems like the Class C guys are getting into tube stuff... www.xforceamps.com/category/Base-Station-Units-81I'll take one of the 3cx3000-1 or the GS35B-2 thank you very much. Wonder if I take a couple of $K down to the big key down this fall in Egg Harbor NJ I could walk away with one of those fine puppies. I've heard they bring "stuff" for sale sometimes. |
|
