Jason -
D3 and D4 are connected in series to increase the Peak Inverse Voltage
of that leg of the voltage doubler power supply. I would NOT turn on
the power supply again! You have just been lucky so far. The B5G5
diode is only rated at 600v PIV, which is why Drake used two in series
in this power supply. If the second one (D3) shorts from overload,
_hopefully_ the fuse will blow before the power transformer blows.
ALL the diodes are replaced, (as is just about everything else besides
the transformer and Bias adjust pot,) by the AC-4R kit, so you'll be
fine once that is installed.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
Jason Bonnough wrote:
Hi all again,
AD5IY still trying to get back on the air with my 4B twins.
I have not ordered the AC-4R kit yet. I plan on it soon though.
I have been looking inside my AC-4 and stuff, which came up with a question for those that have already installed one of the upgrade kits.
I have found that on the original AC-4 that D4 is showing short. On my multimeter on the diode check setting, all B5G5 Diodes are reading somewhere around .5v for forward bias/OL for reverse... standard for diodes, but D4 is reading .08v fwd/rev bias... so the top leg of the 650 line is not held ~1v above ground ( by what I understand on the schematic).
Weird, I can read drawings, I can understand flow, but I really cannot understand what this would do to the ckt...
Nor do I have a multimeter currently at my new location to see if the 650 is actually at 650 or somewhere else... so I wouldn't doubt that will effect the transmitter in some way.
I did take the suggestion of one and setup a lightbulb dummy load seeing how I currently do not have my oil can here yet either(not sure when I can get my can here...) but I wanted to check this out and maybe (hopefully soon) get the AC-4R kit before I really try to start transmitting.
So, would repairing this before getting the AC-4R kit be advantagious? or just
wait for the kit?
and just cause this "pinwheel" of an antenna that I have made is kinda
annoying, anyone got any sites for info or ideas on an good hidden antenna for a 2nd
floor apartment?
Thanks all! Hope to hear ya on the radios when I get them fully up and running!
ET2 Bonnough, Jason A
AD5IY
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