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Author Topic: "Stacking" boat-anchors  (Read 2458 times)
K3STX
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Posts: 973




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« on: July 16, 2010, 08:29:14 AM »

This might be a really dumb question. Most old BA receivers, transmitters, and even speakers have little rubber/plastic "feet". If I put my old Hammarlund speaker or my Heathkit DX-60 DIRECTLY on top of my Hallicrafters HQ-170A, will the rubber feet melt on the DX-60 and make a mess? The HQ-170 has a big mesh lid. Likewise, can I stack my Heathkit HG-10B VFO directly on top of my DX-60? These units are pretty open, and it is not like I use them 24/7, maybe 2 hours operating CW tops a couple of times per week.

What did they do in the old days, do I have to worry about the "melting feet" messing up my nice cabinet? I am not sure overheating is my concern.

paul
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N2EY
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Posts: 3877




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« Reply #1 on: July 16, 2010, 08:50:52 AM »

You probably won't melt the feet - put your hand on the top of the set after it's been on a while to get an idea of how warm it gets.

But directly stacking BAs isn't usually a good idea. First there's the weight problem, but a bigger one is the heat from the ones on the bottom rising into the ones on top. If there's a lot of heat it can shorten component life, but even moderate amounts will extend warmup times and cause thermal drift, etc.

See my shack picture on QRZ for the solution I use.

73 de Jim, N2EY
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AA4PB
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« Reply #2 on: July 16, 2010, 09:25:03 AM »

The HQ-170 has a big mesh lid. Likewise, can I stack my Heathkit HG-10B VFO directly on top of my DX-60? paul

That mesh lid is for ventilation. If you stack a DX60 on top of it you block the air flow and may overheat the HQ-170. If you stack a VFO on top of the DX-60 then the heat from the DX-60 is likely to cause drift problems in the VFO.

You need to provide plenty of air flow space for equipment with tubes - they generate a lot of heat.
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WB2WIK
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« Reply #3 on: July 16, 2010, 02:43:27 PM »

Heating issues aside, you can always replace rubber feet with higher temp ones (nylon, ABS, etc) that won't melt simply due to their chemistry.

What I've often done when "stacking" gear is use "taller" feet than originally supplied, e.g., if the original rubber feet were only 1/4" high, I might go for the gusto and use 1" high feet instead -- leaves a lot more room for ventilation.

Lots of "feet" out there on the market.
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WB2WIK
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« Reply #4 on: July 16, 2010, 02:46:31 PM »

Heating issues aside, you can always replace rubber feet with higher temp ones (nylon, ABS, etc) that won't melt simply due to their chemistry.

What I've often done when "stacking" gear is use "taller" feet than originally supplied, e.g., if the original rubber feet were only 1/4" high, I might go for the gusto and use 1" high feet instead -- leaves a lot more room for ventilation.

Lots of "feet" out there on the market.

I just looked (late) to see where I get my "feet" from, and it's usually from here:

http://www.budwig.com/product.html

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KD6KWZ
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« Reply #5 on: July 16, 2010, 09:12:19 PM »

You can also get hum issues if a power transformer in one rig is close to a receiver front end circuit in another rig.
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W8JI
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« Reply #6 on: July 18, 2010, 07:11:27 PM »

You can also get hum issues if a power transformer in one rig is close to a receiver front end circuit in another rig.

I have more problems when the external power transformer is near the audio stages, especially the audio output transformer.
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VE7DQ
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Posts: 175




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« Reply #7 on: July 18, 2010, 09:53:20 PM »

I won't stack gear.  I've seen too many nice radios that have scratches (oops!) and round, black 'donuts' chemically etched into the paint from those nice, soft rubber feet.  Why risk it?  Just don't do it.
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