[Icom] New Icom owner and list member
Bill, N4QA
[email protected]
Mon, 28 Jul 2003 11:46:18 -0400
Greetings.
My name is Bill, calllsign N4QA.
Licensed since 1965...Amateur Extra and current callsign since 1977.
Main ham radio interests include CW, RTTY, PSK31...all QRP.
I recently bought a used IC-703(hf-only) QRP rig s/n 1801416.
My '703 has a minor problem with intermittent transmitter output power.
Thought I had it fixed when I re-flowed all solder joints of the driver
transistor which is just ahead of the rf transformer which drives the
push-pull finals... a pair of RD07MVS1.
But the problem has re-surfaced.
Can't quite make out the markings on the suspect driver transistor.
Have Icom part number 97714750 (IC-703 service manual) on order and expect
its arrival in a few days.
The problem *seems* to be mechanical in nature.
Using an old plastic Heathkit tuning tool, if I press downward on the
driver, while the rig is transmitting into the Heathkit Cantenna, I can
consistently make the output power stable at whatever power level is set by
the 'Q1 RF POWER' menu and main knob.
This would, again, *seem* to indicate a connection failure of some sort.
Possibly a cracked circuit trace...or, I guess the driver transistor *could*
have an intermittent lead bond.
This SMD driver transistor looks like about a 35-cent part(in quantity).
Anyway, I was wondering if anyone on this list has any knowledge of how
useful the '703's service manual might be and I'd also appreciate any
comments relative to this particular failure.
BTW, I really enjoy operating the '703.
While its transmitter was working this past weekend, I worked much of the
world on 20 m RTTY with 5 watts out to the end-fed longwire...~ four
wavelengths on 20.
73.
Bill, N4QA
http://www.n4qa.com
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