| Author |
Message |
    
Straycat
Junior Member
Username: Straycat
Post Number: 55
Registered: 11-2001
| | Posted on Tuesday, March 02, 2004 - 8:35 pm: | 
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What is the Modulator for the 29 and 25 LTD that you see on ebay all the time? It looks like a cap or resistor in wax or something. What is the value and where does it go ? Does it really give an improvement over normal peaking ? Just curious. |
Jon666
Intermediate Member
Username: Jon666
Post Number: 142
Registered: 11-2003
| | Posted on Sunday, March 21, 2004 - 5:16 pm: |
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in4001 diode not shure where it goes on that radio |
Tech181
Moderator
Username: Tech181
Post Number: 880
Registered: 7-2001
| | Posted on Sunday, March 21, 2004 - 5:47 pm: |
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Save your money. |
Jon666
Intermediate Member
Username: Jon666
Post Number: 143
Registered: 11-2003
| | Posted on Sunday, March 21, 2004 - 5:49 pm: |
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yea what he said. |
Straycat
Member
Username: Straycat
Post Number: 56
Registered: 11-2001
| | Posted on Friday, April 02, 2004 - 9:59 pm: |
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Didn't say I was going to buy one. Can anyone answer the question ? Putting a 68uf cap near the final and a resistor across the opposite side of the board seems to work good on 25's, 29's, 76's and 66's. Is this modulator the same ? Doesn;t show the resistor, only a cap ?? Can a good tech answer please ? Thanks |
Tech8541
Moderator
Username: Tech8541
Post Number: 155
Registered: 12-2003
| | Posted on Saturday, April 03, 2004 - 4:10 pm: |
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no it is different. the 68uf cap that you are talking about is a ceramic disc cap used here to 'couple' the drivers power to the final. bridging this on the bottom of the board allows the driver to 'couple' more power to the final.
the modulator kits are a electrolytic cap and a resistor. the resistor drops the dc voltage to the drivers collector (in other words, it gives a low key). the capacitor allows the audio (ac voltage) to flow unhindered (max peak power). you can buy the pieces to this kit at your local r.shack. |
Straycat
Member
Username: Straycat
Post Number: 57
Registered: 11-2001
| | Posted on Saturday, April 03, 2004 - 4:36 pm: |
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Thanks 8541. Iv'e done the cap mod to a couple of my 29's and a 25. What I am asking is what is the "modulator" that is being sold on e-bay now. They look like a resistor of some type because they are a litle smaller than the cap. The cherry bomb that is being sold looks like a resistor that has been dipped in jello. As far as I knoe they are not the 1N4001 diode that replsces
R-238 in Galaxy and similar exports. |
Straycat
Member
Username: Straycat
Post Number: 58
Registered: 11-2001
| | Posted on Saturday, April 03, 2004 - 5:38 pm: |
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P.S. The 68uf cap that I used for my mod is not a ceramic disc cap but an electrolytic 68uf 63VDC cap. |
Boxcar
Intermediate Member
Username: Boxcar
Post Number: 267
Registered: 4-2002
| | Posted on Monday, April 05, 2004 - 8:53 pm: |
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Straycat, I've done several of these mod's that have a 220uf(16-25 volt) electrolytic capacitor in them. I have the whole sheet if you want it and it explains what resistors to use for certain dead keys. Let me know if you want this and I can email you. If I don't get back in here on this post, post one on the "open forum" with my handle on there because I seldom come in this one.
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Tech8541
Moderator
Username: Tech8541
Post Number: 156
Registered: 12-2003
| | Posted on Monday, April 05, 2004 - 11:55 pm: |
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my mistake, i saw the number 68 and disregarded the 'uf' beside it. i was thinking about the 68 'pf' cap mod. i'm not familiar with a 68uf cap mod, especially with this being the only part used. can you tell us where it went? |
Gunship
Junior Member
Username: Gunship
Post Number: 24
Registered: 8-2003
| | Posted on Thursday, June 17, 2004 - 5:58 am: |
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I was taught to use a 1000 uf,15vdc electrolytic and a 68 ohm,1/4watt resistor. You put the cap in where the jumper alongside the heatsink by the final is,neg. toward the final and solder the resistor to the leads then trim. Give about a 1-1/2 watt deadkey and full swing. Buries the modulation meter on my Dosy. |
