| Author |
Message |
    
Therealporkchop
| | Posted on Monday, September 01, 2003 - 2:51 pm: | 
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I have a 29 that what the echo board and talkback. 1969 final, 1957 driver. Hi/Lo power •••• on it too. The radio was was keying around 4 watts Lo/6 watts high and swinging around 40 watts PEP. I don't know what happened, but now it just keys and doesn't do anything else. I won't modulate or nothing. I have replaced the final and driver, the audio chip, I can't find anything wrong. Anyone know what to do to fix this?
This is a hobby radio. |
Thunderbolt
| | Posted on Monday, September 01, 2003 - 8:49 pm: |
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First thing that is way out of the ordinary is the radio is doing 40 watts! with 1 1969 final. Check another mic on it. I have seen some shops put a disc capacitor on solder side of board near the driver to spike the driver. This might be blown. If it is try to replace it with a 33pf disc capacitor. Wow,40 watts with 1 1969! that means my dual final radios should do 80 watts! Sounds like something went wrong with the swing mod. |
Kc0gxz
| | Posted on Tuesday, September 02, 2003 - 3:00 am: |
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Thunderbolt
You're right Thunderbolt. It can't be done unless he's possibly reading it into maybe a 2 to 1 SWR.
Therealporkchop. The 1969 final has a rated output of 18 watts with a maximum peak of 23-24 watts if you're lucky.
I'm not trying to criticize. Just stating a fact. If your radio tech told you anything else, then find a real one.
Jeff, kc0gxz. |
Adshar64
| | Posted on Tuesday, September 02, 2003 - 4:46 pm: |
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Id say you have a capacitor short. Probaly in the
audio section. need a scoper to trace signal until it goes dead starting from the pre-amp.As for the power level, yes does sound like a cheap power meter and what Jeff say's is fairly typical. The 2sc1969 is capable of up to 35w output with the right impedence network setup around it and a drive increase to ~2 to 2.4 watts.
Bill Eithner a well respected ( as far as tech ability goes) Tech has documented levels up to 40w in experimentation on a 29 ltd. However heat dissapation would never let this level be practical.Most radio's wont tune past 22w because of these limiting factors;
1.Voltage of supply 15v is required for optimum.
2.Impedance network ; most uniden lines use more inductance and less capacitance in the final section to keep good stability, but there is room for good increases here with the right values.
670pf driver - final coupling with final output inductance decrease ie one turn of coil. makes a big difference.
3.Heat;Mica wafer on heatsink will keep medium duty ssb use sustainable to 30W. |
Therealporkchop
| | Posted on Saturday, September 06, 2003 - 4:41 pm: |
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Well fella's all I can say is I'm reading this on a PEP scale. I've tried it with all my mic's. It's average is 35 watts. I'm running the radio on about 14.5 volts. I've had the radio repaired, and I'm still showing about 35 watts and my SWR is at 1.4:1 I'm not saying the radio is doing this, I'm saying this is what my meter is showing. |
Adshar64
| | Posted on Sunday, September 07, 2003 - 4:55 am: |
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Cool . If you can get a bird 43 pep reading meter to compare try it out to see how it compares.
cheers All |
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