| Author |
Message |
    
Bigbob
Senior Member
Username: Bigbob
Post Number: 2202
Registered: 12-2001
| | Posted on Monday, September 12, 2005 - 7:54 pm: | 
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Has anybody tried putting a diode on the center leg of the shunt switch with the banded end toward the pcb so as to control only the negative peaks of audio and bypassing the positive peaks?Bigbob |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1471
Registered: 7-2004
| | Posted on Monday, September 12, 2005 - 9:00 pm: |
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hey bigbob, you aked that question last nite, so, JUST FOR YOU!!!!!! i tried it this morning on a cobra 148 that has NO other mods done to it as of yet. you know what i got??? CRAPOLA!!!! that's what i got! listened on another radio, since i couldn't get anyone to answer me! then i realized why they ignored me! lots of 'swishing' sounds & 'muffled crackles', sounded sort of like a combination of AM off freq & sidebanding, at the same time.
BUT that was only with a diode i pulled from the parts bin. no idea what it was for or what it was from! didn't wanna wipe a $2 schottky, or nte for my xl's... |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 590
Registered: 9-2004
| | Posted on Monday, September 12, 2005 - 9:34 pm: |
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pat, what are the part numbers involved in the mod you tried?
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Bigbob
Senior Member
Username: Bigbob
Post Number: 2207
Registered: 12-2001
| | Posted on Tuesday, September 13, 2005 - 6:22 pm: |
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I tried a 1n914,same thing junk,well back to the drawing board.Bigbob |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 598
Registered: 9-2004
| | Posted on Tuesday, September 13, 2005 - 6:42 pm: |
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bigbob, are you also trying this on a 148 chassis? |
Bigbob
Senior Member
Username: Bigbob
Post Number: 2210
Registered: 12-2001
| | Posted on Wednesday, September 14, 2005 - 6:03 am: |
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No on a dx2517 galaxy.Bigbob |
Bigbob
Senior Member
Username: Bigbob
Post Number: 2211
Registered: 12-2001
| | Posted on Wednesday, September 14, 2005 - 6:05 am: |
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Thank you very much Patzerozero,you are too kind.Bigbob |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1486
Registered: 7-2004
| | Posted on Friday, September 16, 2005 - 5:37 pm: |
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bob-
KV-no clue, pulled it out of the parts drawer, tried it only because bigbob asked & i had a 148 open
really don't think there's going to be any improvements over the mods we've been using. as i said, some radios get 12-13 watts real easy & that's it, others get 20+. there is NO DIFFERENCE in amplifier carrier(it's limited by transistor tolerance anyway) & swing differences have been minimal at best. as long as received audio quality is pleasing to the ear, that is the most important thing...
have done a couple 2290 mods to 296's. 2 went real smooth, a couple have been a REAL hassle. got 10-15 watts carrier & 60+ swing. can't seem to get 'em up to 80 though. in truth, hardly worth the effort. besides, i have no more ferrite coils left... |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 620
Registered: 9-2004
| | Posted on Friday, September 16, 2005 - 9:45 pm: |
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pat, have you ever tried replacing R194 with a diode?
i think it would be a 1N60, or NTE583 or something.
this would be for the 148 chassis.
i read this mod on another site and supposedly it allows full swing at low carrier... blah, blah, blah.
just curious if you'd tried it.
matt |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1494
Registered: 7-2004
| | Posted on Saturday, September 17, 2005 - 11:09 am: |
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tried putting diodes both in series with & flat out replacing resistors in a couple places, as per others recommendations. never got much more then a 'wishy-washy' or 'sidebanding'-type of audio.
remember, 'you don't get nothing for free'? same thing, clipping the limiter is about all you'll get for free(in respect to EASE), volting the final(more work) to get max swing... |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 631
Registered: 9-2004
| | Posted on Saturday, September 17, 2005 - 9:19 pm: |
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thanks for replying pat. that's about what i figured.
have you found the info on how to convert the RX to a mosfet or gaasfet?
this is the most intruiging thing i've heard of in a while.
matt |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1500
Registered: 7-2004
| | Posted on Saturday, September 17, 2005 - 10:13 pm: |
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i've asked & seen that question asked, even of the same 'people' that suggested it here. the question was answered with silence....all i know is the FET in my yaesu ft101e needed to be replaced a couple times over the years (NO receive signal strength at any distance), the last time costing around $15....just for the transistor |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 634
Registered: 9-2004
| | Posted on Saturday, September 17, 2005 - 10:24 pm: |
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yeah, this seems to be the last big CB "secret" in the tech world, and they're not gonna let go without a fight. |
Bigbob
Senior Member
Username: Bigbob
Post Number: 2217
Registered: 12-2001
| | Posted on Monday, September 19, 2005 - 6:48 am: |
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The dx2517 has two fets after the first rf stage,I thought the place for an fet would be in front also,but maybe the placement was to reduce the noise generated by the bi-polar front-end transistor.Bigbob |
