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getting the AC mains out of the TR7+ FAN
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The heatsink and internals of the TR-7 series were designed for the fan to pull heat out of the rig. ?Some prefer to push air into the rig thus driving heat toward the PTO and increasing drift and actually decreasing cooling efficiency for the finals; I've heard that the heatsink design has a patent on it (long expired) but I can't confirm that. For all of my Drake gear, rigs and amplifiers, I've used remote switches to turn things on/off and I leave the power switches in the on position for the respective equipment. ?Haven't had any switch failure, maybe I've been lucky. ?A few years ago I changed most of my arrangements from remote switches to using line conditioners with spike suppressors. ?I used to use Tripp-Lite styles in metal cases but switched to APC models in beige cases; they look good and they work better. ?Better?! ?Yes, the Tripp-Lite models had a high spike at onset, sort of defeating the purpose of using a line conditioner. Switching power supplies can have onset spikes as well. ?One model I have, for 13.8 vdc at 25 amps, has an onset spike higher than 19 vdc when first turned on. ?Hence, I put some "spike suppressors" (or whatever the formal name is for them) on the output of the supply. ?Specs for some of my rigs indicate a max of 16 vdc so that onset spike could be problematic. ?Not sure why reviews of power supplies don't consider the onset spike. ?As a side note, a scope is the best way to measure the onset spike since an analog VOM might have overshoot of the meter movement. Let's all enjoy our hobby. ?And who knows, maybe Hamvention 2025 will lack rain. ?Well, I can dream can't I?
On Tuesday, April 1, 2025 at 07:43:23 AM EDT, Craig W8CS via groups.io <craig_severson@...> wrote:
Great idea. Ordering the connector today as I hate having to drag both cables up and over the bench when I work on this, and I'm still tempting fate by using the volume control on/off. I have my whole house set up on those remote switches by Gosund so it's a simple task to add another.?
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If anyone finds an appropriate 12V muffin fan, let me know. I was going to replace this anyway as it's turbine-like loud. Perhaps something like unit would work.?
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It's currently blowing OUT of the unit; is this the latest best practice??
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Craig/W8CS
Greenville, SC
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I have discovered that the failure mechanism of every Oak switch (the AC power switch on the backs of pots) are mechanical failure of the bronze spring and not due to scorched contacts.? These switches are Unobtanium and not repairable unless you have some very specialised equipment.? Collins owners routinely pay over $100 for a good Oak switch. If your power switch on your Drake does fail, one cheap option is the use a power strip and jumper the Oak switch. Occasionally, you can find good switches in old test equipment and other electronics bric-a-brac from the era. Steve Wedge, W1ES Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Tuesday, April 1st, 2025 at 1:17 PM, Evan via groups.io <k9sqg@...> wrote:
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US Patent 4237521, conveniently stored in the group Files section for your viewing pleasure.
/g/DRAKE-RADIO/files/TR-7/US4237521.pdf I proved experimentally some years ago that the final transistors are cooled much better with the fan pulling air out as Drake intended. Online advice to reverse the fan is misguided. On Tue, 1 Apr 2025 17:17:42 +0000 (UTC) "Evan via groups.io" <k9sqg@...> wrote: I've heard that the heatsink design has a patent on it (long expired) but I can't confirm that. -- 73 -Jim NU0C |
Jim Shorney
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