Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Al -
Perhaps the difference between 6-1/4 and 5A fuses is a result of the
differing power requirements for the TR-4 and the T-4X. I use 5A
Slo-Blo fuses in mine, and haven't had one blow yet.
The AC-4 manual that I have shows 5A SB for 120 VAC and 3A SB for 240
VAC. Interestingly, the Spare Parts list for the AC-3/AC-4 shows a 5A
SB fuse AND a 6-1/4 Fast Blow fuse.
A quick survey shows that the T-4X manual, with the AC-3 specified, says
5 and 3A SB.
The T-4XB manual, with the AC-4, shows 6-1/4A SB and 3A SB.
The T-4XC manual, with the AC-4, shows 5A SB and 3A SB.
The TR-4C (late) manual, with the AC-4, shows 5A SB and 3A SB.
Writing all this, I'm beginning to remember a time when 5A fuses were
blowing with TR-4's, and Drake advised to up the fuse to 6-1/4A,
possibly because they were tired of the complaints!.
Maybe when the B Line came out speech processing was new and being over
zealously applied!!
I'm surprised that your unit is running with a 3A SB. The turn-on surge
for power supplies with huge capacitor input filters is pretty hefty!
The BEST fuse is the smallest one that doesn't blow routinely!
The fuse is there primarily to protect the transformer (and the house!)
when the filter caps short. When that happens, it won't matter which
size fuse you have in there. When the bias supply fails, a smaller
fuse _might_ save the final section of the transmitter from melt-down.
73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual
<http://www.k4oah.com>
n7ioh wrote:
n7ioh <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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I have an AC-4 power supply and would like to know the correct fuse
for 120vac using it with the T-4XC transmitter. I have the AC-4 power
supply sn 55719 and it has a regular 3A fuse in it, not a slo blo. I
have not used the AC-4 yet and am planning to install the PC board kit
from the Heathkit shop first. The manual I bought that is a reprint
is showing a 6 1/4 amp slo blo fuse for 120vac. When I go to the
Drake Museum and look up the AC-4 under the 4 line accessories in the
schematic it is showing a 5 amp slo blo fuse for 120vac. I am
guessing that I may not be the only one here with the wrong fuse in
the AC-4 based on the information published.
Thanks, Al, n7ioh
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