[Elecraft] A couple of KPA1500 remote operating questions

Wed Jun 10 22:07:10 EDT 2020

The concern is 100% noise. Heat I don’t mind, and it helps in the winter.

I’ll see about a HEPA room filter. The area is a concrete crawl space below my shack, about 3 feet high and 25 feet long, with a sheltered window at one end and access to the main part of the basement at the other. I would plan to put the amp about 8 feet in from the basement entrance, and against an exterior wall.

I don’t know what material is dropping over everything, but it’s noticeable. Maybe concrete dust? Something from the insulation in the ceiling?? I figured if I went down every week or two with a compressor and just blasted air into the back to blow anything out that would help. I see you point about air filters. 

I have a Cat-6 line in there now to an old PC, the drop to my station, and another one to my weather station’s RPI. With good shielded coax running in the direction opposite direction to the Cat-6 and a few ferrites I think I’ll be OK in that area. It’s just the dust contamination I’m concerned about. 

- pjd

From: Bob Wilson, N6TV <n6tv at arrl.net> 
Sent: Wednesday, June 10, 2020 9:10 PM
To: Peter Dougherty <lists at w2irt.net>; Elecraft Reflector <Elecraft at mailman.qth.net>
Subject: Re: [Elecraft] A couple of KPA1500 remote operating questions

On Wed, Jun 10, 2020 at 4:33 PM Peter Dougherty <lists at w2irt.net <mailto:lists at w2irt.net> > wrote:

1.      The area it will be going into is dusty.

Dust is not good for amplifiers.  They must move lots of air through the amplifier.  Do you really have to put it there?  Is it because you can't stand the fan noise?  Or the heat?

I suspect it's particulate dropping down from the insulation in the ceiling.

Any way to fix that?  Maybe a HEPA room filter?

I plan to put a shelf about 10 inches over top of the amp but I'm wondering if
this might be a problem.

Well, it won't keep the dust out.  Cool air is blown into the amplifier from the rear fans, and out the top (and also through gaps in the front panel if the fan speed gets high enough).  A shelf over the amp. could force the hot exhaust air to circulate back down close to the intake.  Not good.

If so, how often should I get down there with a compressor to blow the crud out of everything? Or maybe put a piece of fine
air filter material over the fan inlet?

A filter will probably reduce air flow, and put more stress on the fans.  Not good.

2.      The crawlspace is not heated and probably gets into the 40s or even
30s during the winter. Would this be a risk?

Cold is good.  Amps like to be cold (KPA1500 has more gain when cold than when not).  But if moisture or condensation is a problem down there, not good.

3.      I'm using the amp with a K3s. At the moment I have a Y-box from the
accessory port, and a cable from the Y-box to the amp. Since this won't be
on the same floor as the radio, how can I get this working with the radio?

A long M/F DE-15 cable should work.  I don't know what the length limit is.  10 to 15 feet should be OK if you have 2.5' from the K3 ACC to the Y-BOX.   But use a well shielded cable.  I recommend this one for extra long runs:

https://www.cablesondemand.com/category/HD15/product/CS-DSPMHD15MF/URvars/Items/Library/InfoManage/CS-DSPMHD15MF.htm 

If I site the amp immediately below where it is now I could probably run a
10' DB15 extension cable down from the Y-box to the amp, but I'm pretty sure
that will violate all kinds of fire regs. Not sure how I can do this.

Fire regs?  Can't comment on that, but there is no more than 13V on any pin, and very little current, so it's hard to imagine how that cable could cause a fire.

But once the amp. is down there, how will you monitor it?  Are you planning to run a long USB or Ethernet cable down there as well?  A long USB cable will probably need ferrites.  A long Ethernet cable should generate RFI if you use the unshielded type.  

Or are you going to keep a PC in the crawlspace, connected by WiFi, and use KPA1500 Remote software?

73,

Bob, N6TV