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Posted by: Bill, N4QA Posted On: 08/22/03 Subject: Re: IC703 Transmitter dead Message Posted: In Reply to: Re: IC703 Transmitter dead posted by Steve W9HC on 08/21/03 Steve and gang, No, I had to replace Q150, the driver transistor just ahead of the finals. Once Q150 had gone totally open, my '703 would put out only 10 milliwatts, all bands. The reason my output didn't go all the way to zero was the fact that a small amount of energy from the pre-driver stage passed through a series resistor-capacitor network which is connected between the driver transistor's gate and drain leads, providing just enough drive for the finals to produce 10 milliwatts output. While I waited for the replacement part...a Mitsubishi RD01MUS1 surface-mount MOSFET... to arrive, I removed the bad part from the rig. The funny thing is, I worked Venezuela from here in Pulaski County, Virginia on 20-meter BPSK31 with the '703 putting out only 10 mW p.e.p. But, that was my only contact with the '703 missing the driver transistor. Anyway, my IC-703 will now do the full ten Watts out, if I want. But, I have the max power out limit set for 5 Watts to stay within the QRP limit. There's one shipload of technology in the '703. 73. |
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