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Message |
    
Audiophile73
Member
Username: Audiophile73
Post Number: 97
Registered: 5-2004
| | Posted on Sunday, April 30, 2006 - 10:42 pm: | 
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I am driving a ts modulator to a straight 4 pill amp (2879), I need my radio to key low and swing high. I can get it to key 1 watt but it only swings to 2. If I upgrade the final to a 2sc1969 would it swing better. |
Ironfoof
New member
Username: Ironfoof
Post Number: 7
Registered: 5-2006
| | Posted on Sunday, May 14, 2006 - 12:00 pm: |
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1 watt and swings - 2 watts? Sounds like your way out of adjustment or your final is nearly toast. I havent seen a huge difference personally between a 2sc1969 and a 2sc2078 for instance. I think their specs are very simular. I would try a peak and tune or replace finals. My 2 bits. |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 674
Registered: 11-2002
| | Posted on Sunday, May 14, 2006 - 3:37 pm: |
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Is that swing measured off PEP or RMS?
RMS might be right depending on the radio it's in and how it's been tuned. True you could have half toasted finals.
I personally think under normal conditions you wouldn't see that big of an increase. But I think you'd have a little more audio anyway. I could be wrong, but hey sooner or later I've got to foul up.
Most importantly if you wanted to sell it later, you would sell it twice as fast with the upgrade. People are quicker to jump on any radio that's got the 1969 in it over a 2078. Just check out hehay's auction site and see for yourself.... |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1585
Registered: 9-2004
| | Posted on Sunday, May 14, 2006 - 5:34 pm: |
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audiophile, detuning the TX coils is not the way to lower your deadkey.
there are parts to change in the final amp section that will allow a lower dead key with full potential swing.
isnt that radio the same as the cobra 29ltd?
if it is, and you cant find mods for it on the net, then you're just not trying.
matt |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 678
Registered: 11-2002
| | Posted on Sunday, May 14, 2006 - 9:51 pm: |
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I don't know Matt, it is kinda hard to find anything on a 78, or is that a 68 or 66 I'm thinking of.
Regardless I think you're right about the Cobra thing working for that radio too.
Look up the amp swing mod for a Cobra. You'll need a 220uF 16 or 25V cap and then you install a resistor across the back to get the key you want. I believe there is a jumper directly in front of the final you remove. Can't remember the number, maybe JP9? |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1591
Registered: 9-2004
| | Posted on Sunday, May 14, 2006 - 11:56 pm: |
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usually, if i cant find anything on a certain radio, i'll try to find out what its counterparts are, and that will usually produce some results.
if there are no counterparts, then its too oddball to bother with anyway.LOL
matt |
The_bandit
Junior Member
Username: The_bandit
Post Number: 12
Registered: 8-2002
| | Posted on Monday, May 15, 2006 - 2:05 am: |
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I believe the jumper you want to remove on a PC78 is either JV6 or JV36.. it's the one directly in front of the final though... remove it and replace it with a 470uF 25v Electrolytic capacitor with the Negative side facing the rear of the radio.. On the solder side of the board, solder in a couple of 1k resistors in parallel across the same spots you soldered the capacitor in. |
