It has taken me a little longer than anticipated to get to this stage, as I replaced the crystals and did the initial tune up for 70cm way back in 2016! But today I finally embarked on the task of changing the band specific capacitors,
In order to replace these caps, the side of the radio needed to be removed, this involved also desoldering the 'call' switch, as well as removing the bolts through the PTT buttons. Whenever I work on something as delicate as this, I take copious photos - so I can see where everything goes back to!
The first two capacitors are along the very edge of the PCB, and up against one of the filters.
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| C36, 2nd from left (brown) and C35, 4th from left (orange) fitted |
If fitting these was fiddly, then the next three were a nightmare! These three were in-board, and surrounded by other much taller, and very delicate parts. Replacing these took all the skill I could muster, and a lot of will power to ignore the pain of burning fingers!
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| C45 black left of power transistor; C47 above transistor; C11 left of green cap |
A minor disaster awaited me - in desoldering C11, I inadvertently also desoldered C13 and R16! Both of which fell out. It took a lot of desoldering to clean up and open the PCB holes in order to be able to get them back in!
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| PCB holes cleared to replace C13 and R16, and fit new C11 |
All this took over two hours! I then had to reposition and secure the wiring loom on the track side, refit the screening plate, and ensure that the tiny coax that goes to one leg of C47 was correctly resoldered.
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| The wiring loom and shielding |
So now im in a position to test again. All being well, the set will power up! If I get past that milestone, im hoping that at the very least I will now be able to bring the Tx power up closer to the designed 500mW. Whether I get any improvement on receive we'll have to wait and see.
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