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Josh Dunnigan
Posted on Friday, October 12, 2001 - 2:13 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)
Hello, 307 hopefully you can help me with this one

I have a TRC-458 navaho base which i picked up for free. I replaced the 1156H audio IC and brought back the receive. I opened the modulation up to 100% and was getting a 4 watt dead key which swung to around 8 watts on AM.

I put the channel mod in it, and got all my channels for the UPD858 chip in the radio.

My output power dropped to around 1.5-2 watts with little or no swing and very low modulation. The RX side is still working fine.

Thinking I had a final amplifier problem I replaced the 1307 Final with a 2sc2078 or something of the sort. My output did not change so I replaced the 2sc1306 driver with a driver out of a cobra 29 which i stole the 2sc2078 from. My output power dropped to zero so I put the old driver back in. Still nothing.

Now the radio is not putting out any power in any mode.. My voltage supplies around the final and driver are around 6volts at the collector on transmit and 2 volts (driver) .75 volts (final) on transmit at the emitter

SSB has a higher supply voltage of 13.8v but the same voltages at the emitter.

I am at wits end since I do not have Sams Photofact #207 which has the TRC-458 Navaho in it.. Many people have offered their advice but nothing has changed.
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jyd
Posted on Saturday, October 13, 2001 - 4:46 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)
go to radio shack and get the transisters that it is suposed to have then check out put voltage on your power supply,did you tune it up?you might have done something wrong when you done the channel mod. some radios act crazy when you try do do mods to them
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307
Posted on Sunday, October 14, 2001 - 6:19 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)
Sounds to me like you lost the LO (Local Oscillator). The bias is sounding correct exept it sounds to me like you have no drive.
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jyd
Posted on Thursday, October 18, 2001 - 4:31 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)
i know whats wrong, most channel kits require the radio to be realihgned.when you put the channel kit in it changes the frequency there for the radio needs to be retuned on all bands

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