A couple of KPA1500 remote operating questions

[Peter W2IRT]

Hi all,
Within the next week or two I am hoping to relocate my KPA-1500 to a
basement crawlspace, but before calling in the electrician and getting ready
to move it, I have a couple of questions.

 

1. The area it will be going into is dusty. To the point that when I'm
in there to check on my cables or retrieve an equipment box that's stored
down there I have to wear a face mask or I'll be coughing for hours . I
suspect it's particulate dropping down from the insulation in the ceiling. I
plan to put a shelf about 10 inches over top of the amp but I'm wondering if
this might be a problem. 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?
2. The crawlspace is not heated and probably gets into the 40s or even
30s during the winter. Would this be a risk?
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?
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.

 


---------------------------------------------
73 and Good DX
Peter, W2IRT



President, North Jersey DX Association

DXCC Card Checker
Letter O Manager, ARRL Incoming 2nd District QSL bureau

 

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[Bob Wilson, N6TV]

On Wed, Jun 10, 2020 at 4:33 PM Peter Dougherty <[hidden email]> 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
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[Michael Walker]

My 2 cents

I ran a KPA500 in a boat house for 6 or 7 years.  It wasn't heated, covered
or filtered.  It saw temperatures from -25C to +35C and humidities from 15%
to 99% and it worked perfectly for those  years.   In fact, it still works
today but I just replaced it with a higher power amp.

This was in Ontario NE of Toronto.  From October to April I never saw it
and controlled it remotely by the PC that was sitting beside it.

It wasn't bothered by the high summer humidity or the cold winter air.

Every few years I blew some dust out of it.

I ran a bunch of CW, SSB and RTTY contests on it, some in January and it
took a while for the PA temp to reach 0C.  I figured that if all the
electronics in my car would work at -35C then the KPA500 would as well.

Short story, I plugged it in, turned it on and used it.  That may not what
you wish to do but it worked perfectly for me.

And, it still works perfectly today.  Just in a different purpose.

mike va3mw



On Wed, Jun 10, 2020 at 7:33 PM Peter Dougherty <[hidden email]> wrote:

> Hi all,
> Within the next week or two I am hoping to relocate my KPA-1500 to a
> basement crawlspace, but before calling in the electrician and getting
> ready
> to move it, I have a couple of questions.
>
>
>
> 1.      The area it will be going into is dusty. To the point that when I'm
> in there to check on my cables or retrieve an equipment box that's stored
> down there I have to wear a face mask or I'll be coughing for hours . I
> suspect it's particulate dropping down from the insulation in the ceiling.
> I
> plan to put a shelf about 10 inches over top of the amp but I'm wondering
> if
> this might be a problem. 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?
> 2.      The crawlspace is not heated and probably gets into the 40s or even
> 30s during the winter. Would this be a risk?
> 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?
> 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.
>
>
>
>
> ---------------------------------------------
> 73 and Good DX
> Peter, W2IRT
>
>
>
> President, North Jersey DX Association
>
> DXCC Card Checker
> Letter O Manager, ARRL Incoming 2nd District QSL bureau
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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[Peter W2IRT]

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 <[hidden email]>
Sent: Wednesday, June 10, 2020 9:10 PM
To: Peter Dougherty <[hidden email]>; Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] A couple of KPA1500 remote operating questions

 

On Wed, Jun 10, 2020 at 4:33 PM Peter Dougherty <[hidden email] <mailto:[hidden email]> > 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

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