KPA-1500 Fan Noise - YouTube ?

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KPA-1500 Fan Noise - YouTube ?

Richard Thorne-4
This fan noise issue has me concerned to the point that I’m considering cancelling my order.

While the amp won’t be on my operating desk, it will be on a rack next to my operating desk.  Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.

Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?

From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.

Thanks

Rich - N5ZC

Sent from my iPhone
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Re: KPA-1500 Fan Noise - YouTube ?

Elecraft mailing list
 Rich

You pretty much hit the nail on the head about solid state amps.  As they say there's no free lunch.  Solid state has made great strides in high power ampsbut its still solid state and a p/n junction or some form thereof.  1500 watts of heat in those junctions has to be cooled down or it won't be long before it needsnew parts.
Depending on your operating habits (contesting, casual, or whatever) there will be varying degrees of fan noise.  The higher the duty cycle the higher thefan requirements.  Pick your poison, a small light weight amp easy to move around or one you need a fork lift to pick up.  I prefer tube amps for a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the living room temporarily) but I'm still glad I got the kpa1500 at least so far.
The kpa sits nicely on top of the Acom without causing the table they sit on to crash to the floor in pieces, hi.  I'm surprised nobody has made a you tube ofthe amp in operation actually.  But there are only just over 200 of the new amps out there.  Good luck with your investigation, Rich.
BillK3WJV

    On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <[hidden email]> wrote:  
 
 This fan noise issue has me concerned to the point that I’m considering cancelling my order.

While the amp won’t be on my operating desk, it will be on a rack next to my operating desk.  Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.

Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?

From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.

Thanks

Rich - N5ZC

Sent from my iPhone
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Re: KPA-1500 Fan Noise - YouTube ?

Michael Walker
Bill is correct

You have to move air to cool down those devices and it takes fans to do
it.  Water cooling might work if you wish to modify it.  :)

But, there is no free lunch as was mentioned.  Be prepared that any 1500
watt LMDOS amp requires cooling but since there is no tube, they are built
in smaller boxes, so you get smaller fans that have to move more air.

The B26 is somewhat quieter I think, but they worked on some things to make
it quieter like extending the fan out the back so there is less disturbed
air when it hits the fan blades.

They aren't that loud and if were good headphones, you won't notice at all.

my 2 cents, Mike va3mw


On Fri, Jun 1, 2018 at 8:32 PM, Bill Stravinsky via Elecraft <
[hidden email]> wrote:

>  Rich
>
> You pretty much hit the nail on the head about solid state amps.  As they
> say there's no free lunch.  Solid state has made great strides in high
> power ampsbut its still solid state and a p/n junction or some form
> thereof.  1500 watts of heat in those junctions has to be cooled down or it
> won't be long before it needsnew parts.
> Depending on your operating habits (contesting, casual, or whatever) there
> will be varying degrees of fan noise.  The higher the duty cycle the higher
> thefan requirements.  Pick your poison, a small light weight amp easy to
> move around or one you need a fork lift to pick up.  I prefer tube amps for
> a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the
> living room temporarily) but I'm still glad I got the kpa1500 at least so
> far.
> The kpa sits nicely on top of the Acom without causing the table they sit
> on to crash to the floor in pieces, hi.  I'm surprised nobody has made a
> you tube ofthe amp in operation actually.  But there are only just over 200
> of the new amps out there.  Good luck with your investigation, Rich.
> BillK3WJV
>
>     On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <
> [hidden email]> wrote:
>
>  This fan noise issue has me concerned to the point that I’m considering
> cancelling my order.
>
> While the amp won’t be on my operating desk, it will be on a rack next to
> my operating desk.  Remoting the amp is not an option. Quite frankly I have
> no interest in remoting the amp.
>
> Is there anyone out there that has a KPA-1500 willing to post a YouTube
> video so we can hear the fan in action and judge the noise for ourselves?
>
> From the research I’ve done it appears that if you want a solid state amp,
> regardless of make, you need to be prepared for fan noise.
>
> Thanks
>
> Rich - N5ZC
>
> Sent from my iPhone
> ______________________________________________________________
> 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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> 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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Re: KPA-1500 Fan Noise - YouTube ?

Dr. William J. Schmidt, II
In reply to this post by Elecraft mailing list
So just a bit of thermodynamics... if the input to any amplifier is 1500 watts and it is 50% efficient, since energy is conserved, 750 watts will come out in another form.. and in this case it's heat.  Doesn't matter what the converter is (transistor, tube, resistor, etc.).  It all behaves the same.  Need to get rid of 750 watts of heat.  The only difference may be the way the heat is taken away of the converter... convection (heat sink), forced convection (heat skin plus fan), liquid convection (water cooled heat sink).  The poison is the heat removal device not the converter.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email:  [hidden email]



-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Bill Stravinsky via Elecraft
Sent: Friday, June 1, 2018 7:33 PM
To: Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?

 Rich

You pretty much hit the nail on the head about solid state amps.  As they say there's no free lunch.  Solid state has made great strides in high power ampsbut its still solid state and a p/n junction or some form thereof.  1500 watts of heat in those junctions has to be cooled down or it won't be long before it needsnew parts.
Depending on your operating habits (contesting, casual, or whatever) there will be varying degrees of fan noise.  The higher the duty cycle the higher thefan requirements.  Pick your poison, a small light weight amp easy to move around or one you need a fork lift to pick up.  I prefer tube amps for a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the living room temporarily) but I'm still glad I got the kpa1500 at least so far.
The kpa sits nicely on top of the Acom without causing the table they sit on to crash to the floor in pieces, hi.  I'm surprised nobody has made a you tube ofthe amp in operation actually.  But there are only just over 200 of the new amps out there.  Good luck with your investigation, Rich.
BillK3WJV

    On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <[hidden email]> wrote:  
 
 This fan noise issue has me concerned to the point that I’m considering cancelling my order.

While the amp won’t be on my operating desk, it will be on a rack next to my operating desk.  Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.

Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?

From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.

Thanks

Rich - N5ZC

Sent from my iPhone
______________________________________________________________
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Post: mailto:[hidden email]

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Re: KPA-1500 Fan Noise - YouTube ?

ke9uw
In reply to this post by Michael Walker
Some years ago we cooled a PDP11 by putting the fan remote and running a dryer hose to the computer. How about putting the fan in the basement and the rig on the desk where it’s handy?

Chuck Jack
KE9UW

Sent from my iPhone, cjack

> On Jun 1, 2018, at 7:57 PM, Michael Walker <[hidden email]> wrote:
>
> Bill is correct
>
> You have to move air to cool down those devices and it takes fans to do
> it.  Water cooling might work if you wish to modify it.  :)
>
> But, there is no free lunch as was mentioned.  Be prepared that any 1500
> watt LMDOS amp requires cooling but since there is no tube, they are built
> in smaller boxes, so you get smaller fans that have to move more air.
>
> The B26 is somewhat quieter I think, but they worked on some things to make
> it quieter like extending the fan out the back so there is less disturbed
> air when it hits the fan blades.
>
> They aren't that loud and if were good headphones, you won't notice at all.
>
> my 2 cents, Mike va3mw
>
>
> On Fri, Jun 1, 2018 at 8:32 PM, Bill Stravinsky via Elecraft <
> [hidden email]> wrote:
>
>> Rich
>>
>> You pretty much hit the nail on the head about solid state amps.  As they
>> say there's no free lunch.  Solid state has made great strides in high
>> power ampsbut its still solid state and a p/n junction or some form
>> thereof.  1500 watts of heat in those junctions has to be cooled down or it
>> won't be long before it needsnew parts.
>> Depending on your operating habits (contesting, casual, or whatever) there
>> will be varying degrees of fan noise.  The higher the duty cycle the higher
>> thefan requirements.  Pick your poison, a small light weight amp easy to
>> move around or one you need a fork lift to pick up.  I prefer tube amps for
>> a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the
>> living room temporarily) but I'm still glad I got the kpa1500 at least so
>> far.
>> The kpa sits nicely on top of the Acom without causing the table they sit
>> on to crash to the floor in pieces, hi.  I'm surprised nobody has made a
>> you tube ofthe amp in operation actually.  But there are only just over 200
>> of the new amps out there.  Good luck with your investigation, Rich.
>> BillK3WJV
>>
>>    On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <
>> [hidden email]> wrote:
>>
>> This fan noise issue has me concerned to the point that I’m considering
>> cancelling my order.
>>
>> While the amp won’t be on my operating desk, it will be on a rack next to
>> my operating desk.  Remoting the amp is not an option. Quite frankly I have
>> no interest in remoting the amp.
>>
>> Is there anyone out there that has a KPA-1500 willing to post a YouTube
>> video so we can hear the fan in action and judge the noise for ourselves?
>>
>> From the research I’ve done it appears that if you want a solid state amp,
>> regardless of make, you need to be prepared for fan noise.
>>
>> Thanks
>>
>> Rich - N5ZC
>>
>> Sent from my iPhone
>> ______________________________________________________________
>> 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]
>> ______________________________________________________________
>> 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]
>>
> ______________________________________________________________
> 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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Re: KPA-1500 Fan Noise - YouTube ?

Elecraft mailing list
In reply to this post by Dr. William J. Schmidt, II
 Tube amp just has the single fan that doesn't spin at 9000 rpm like the little solid state fans, hi.  Same noise level if xmit or not.
BillK3WJV

    On Friday, June 1, 2018, 9:04:45 PM EDT, Dr. William J. Schmidt <[hidden email]> wrote:  
 
 So just a bit of thermodynamics... if the input to any amplifier is 1500 watts and it is 50% efficient, since energy is conserved, 750 watts will come out in another form.. and in this case it's heat.  Doesn't matter what the converter is (transistor, tube, resistor, etc.).  It all behaves the same.  Need to get rid of 750 watts of heat.  The only difference may be the way the heat is taken away of the converter... convection (heat sink), forced convection (heat skin plus fan), liquid convection (water cooled heat sink).  The poison is the heat removal device not the converter.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email:  [hidden email]



-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Bill Stravinsky via Elecraft
Sent: Friday, June 1, 2018 7:33 PM
To: Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?

 Rich

You pretty much hit the nail on the head about solid state amps.  As they say there's no free lunch.  Solid state has made great strides in high power ampsbut its still solid state and a p/n junction or some form thereof.  1500 watts of heat in those junctions has to be cooled down or it won't be long before it needsnew parts.
Depending on your operating habits (contesting, casual, or whatever) there will be varying degrees of fan noise.  The higher the duty cycle the higher thefan requirements.  Pick your poison, a small light weight amp easy to move around or one you need a fork lift to pick up.  I prefer tube amps for a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the living room temporarily) but I'm still glad I got the kpa1500 at least so far.
The kpa sits nicely on top of the Acom without causing the table they sit on to crash to the floor in pieces, hi.  I'm surprised nobody has made a you tube ofthe amp in operation actually.  But there are only just over 200 of the new amps out there.  Good luck with your investigation, Rich.
BillK3WJV

    On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <[hidden email]> wrote: 
 
 This fan noise issue has me concerned to the point that I’m considering cancelling my order.

While the amp won’t be on my operating desk, it will be on a rack next to my operating desk.  Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.

Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?

From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.

Thanks

Rich - N5ZC

Sent from my iPhone
______________________________________________________________
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Re: KPA-1500 Fan Noise - YouTube ?

Wes Stewart-2
In reply to this post by ke9uw
What's a basement?  On towertalk they talk about letting the lawn grow over
ground radials.  I wonder what a lawn is.  They also say to install ground rods
where the rain will hit them.  I wonder what rain is.

Wes  N7WS

On 6/1/2018 6:05 PM, hawley, charles j jr wrote:
> Some years ago we cooled a PDP11 by putting the fan remote and running a dryer hose to the computer. How about putting the fan in the basement and the rig on the desk where it’s handy?
>
> Chuck Jack
> KE9UW

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Re: KPA-1500 Fan Noise - YouTube ?

Don Butler
In reply to this post by Richard Thorne-4
I personally think all the banter about KPA1500 fan noise has created confusion.   Yes, the amp has three fans with five selectable fan speeds..and since the amp is small the fans are necessarily small and therefore must run faster …. and as the fan speed increases the pitch and noise levels increase.. and the higher fan speeds do indeed create significant noise, but the higher speeds will rarely (if ever) be needed.  I have had my KPA1500 about 3 months now, and have manually switched to level 3 just a couple times (cq running during cw contest and major cw split pileup), and thus far I have never had to use levels 4 or 5.   The fans operate automatically as per heat sink temperature but can also be manually controlled.   Fan speeds 1 and 2, to me, are just like any other amplifier, and noise is not problematic.  Levels 3, 4, and 5 however are definitely noisy and can become annoying…. But again, those speeds are rarely necessary.   IMHO, with five selectable speeds, the KPA1500 could very likely have the most capable cooling system available in any amateur amplifier.... and I call that a plus.  The three additional amplifiers in my shack (Alpha 9500, Icom PA1 and Alpha 89) make noise too, but it’s probably a good bet that they do not have cooling capability that matches the KPA1500’s five speed fans.

Don, N5LZ

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Richard Thorne
Sent: Friday, June 01, 2018 5:55 PM
To: [hidden email]
Subject: [Elecraft] KPA-1500 Fan Noise - YouTube ?

This fan noise issue has me concerned to the point that I’m considering cancelling my order.

While the amp won’t be on my operating desk, it will be on a rack next to my operating desk.  Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.

Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?

From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.

Thanks

Rich - N5ZC

Sent from my iPhone
______________________________________________________________
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Re: KPA-1500 Fan Noise - YouTube ?

Don Wilhelm
In reply to this post by Dr. William J. Schmidt, II
Only one bit of correction.  If the output power is 1500 watts and the
efficiency is 50%, that 1500 watts is only half the total power
consumed, so there is 1500 watts of power that must be exhausted as heat.

Yes, it is all thermodynamics, that heat must be dissipated somehow.
Fans are the obvious solution.

73,
Don W3FPR

On 6/1/2018 8:59 PM, Dr. William J. Schmidt wrote:

> So just a bit of thermodynamics... if the input to any amplifier is 1500 watts and it is 50% efficient, since energy is conserved, 750 watts will come out in another form.. and in this case it's heat.  Doesn't matter what the converter is (transistor, tube, resistor, etc.).  It all behaves the same.  Need to get rid of 750 watts of heat.  The only difference may be the way the heat is taken away of the converter... convection (heat sink), forced convection (heat skin plus fan), liquid convection (water cooled heat sink).  The poison is the heat removal device not the converter.
>
>
> Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
>
> Owner - Operator
> Big Signal Ranch – K9ZC
> Staunton, Illinois
>
> Owner – Operator
> Villa Grand Piton – J68HZ
> Soufriere, St. Lucia W.I.
> Rent it: www.VillaGrandPiton.com
> Like us on Facebook!
>
> Moderator – North American QRO Group at Groups.IO.
>
> email:  [hidden email]
>
>
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On Behalf Of Bill Stravinsky via Elecraft
> Sent: Friday, June 1, 2018 7:33 PM
> To: Elecraft Reflector <[hidden email]>
> Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?
>
>   Rich
>
> You pretty much hit the nail on the head about solid state amps.  As they say there's no free lunch.  Solid state has made great strides in high power ampsbut its still solid state and a p/n junction or some form thereof.  1500 watts of heat in those junctions has to be cooled down or it won't be long before it needsnew parts.
> Depending on your operating habits (contesting, casual, or whatever) there will be varying degrees of fan noise.  The higher the duty cycle the higher thefan requirements.  Pick your poison, a small light weight amp easy to move around or one you need a fork lift to pick up.  I prefer tube amps for a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the living room temporarily) but I'm still glad I got the kpa1500 at least so far.
> The kpa sits nicely on top of the Acom without causing the table they sit on to crash to the floor in pieces, hi.  I'm surprised nobody has made a you tube ofthe amp in operation actually.  But there are only just over 200 of the new amps out there.  Good luck with your investigation, Rich.
> BillK3WJV
>
>      On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <[hidden email]> wrote:
>  
>   This fan noise issue has me concerned to the point that I’m considering cancelling my order.
>
> While the amp won’t be on my operating desk, it will be on a rack next to my operating desk.  Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.
>
> Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?
>
>  From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.
>
> Thanks
>
> Rich - N5ZC
>
> Sent from my iPhone
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Re: KPA-1500 Fan Noise - YouTube ?

N2TK
In reply to this post by Wes Stewart-2
Wes, tnx for the chuckle.
No lawn mower, no umbrella, no place to store unwanted and unnecessary junk. You are livin' a dream.
And you can string your dipoles from the Saguaro. Hey, if the arms are the correct lengths you can string some verticals to cover multiple bands. And if the arms are the same length maybe you can make a phased array?
I don't miss being entertained by the rattlers and Javelinas on the golf course in Tucson.
73,
N2TK, Tony



-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Wes Stewart
Sent: Friday, June 01, 2018 9:28 PM
To: [hidden email]
Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?

What's a basement?  On towertalk they talk about letting the lawn grow over ground radials.  I wonder what a lawn is.  They also say to install ground rods where the rain will hit them.  I wonder what rain is.

Wes  N7WS

On 6/1/2018 6:05 PM, hawley, charles j jr wrote:
> Some years ago we cooled a PDP11 by putting the fan remote and running a dryer hose to the computer. How about putting the fan in the basement and the rig on the desk where it’s handy?
>
> Chuck Jack
> KE9UW

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Re: KPA-1500 Fan Noise - YouTube ?

Gmail - George
In reply to this post by Don Wilhelm
One other thought to keep in mind - solid state amps need a lower delta T
than tube amps. Tubes like to run hot - solid state devices not so much.

I've seen a tube with the fins so hot that the solder was in globs, while
the transmitter was still operating. I doubt any solid state final would
have survived that heat.

When we installed our solid state TV transmitter, it was a new learning
curve in cooling. Both transmitters were 30 kW class AB1. The tube
transmitter moved air faster through 3 tubes but had almost 3 times the
temperature rise than the specs for the solid state transmitter. Our HVAC
company and architect worked on several complex systems with air mixers
until we just decided to use wall mounted air conditioners into the room
behind the transmitter racks and exhausted to the front of the transmitters.

Our solid state transmitter did meet the OSHA limit for 8 hours exposure to
noise but just barely. It was very noisy compared to the tube unit.

No tube transmitter I have ever used had a temperature shut down on any of
the tube stages.

73 George AI4VZ



-----Original Message-----
From: Don Wilhelm

Only one bit of correction.  If the output power is 1500 watts and the
efficiency is 50%, that 1500 watts is only half the total power
consumed, so there is 1500 watts of power that must be exhausted as heat.

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Re: KPA-1500 Fan Noise - YouTube ?

WILLIE BABER
In reply to this post by Richard Thorne-4
While running stations on 160m at a high rate, the finals of an Omni VI got so hot that output dropped to zero.  Once the finals cooled for maybe about five minutes, full output returned.  We then put a small fan on the heat sink fins and experienced no further problem.  No damage at all to the components.  Unfortunately, the same Omni VI was hit by lightning some years later.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/

--------------------------------------------
On Sat, 6/2/18, Gmail - George <[hidden email]> wrote:

 Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?
 To: [hidden email]
 Date: Saturday, June 2, 2018, 6:10 AM
 
 One other thought to keep in mind
 - solid state amps need a lower delta T
 than tube amps. Tubes like to run hot - solid
 state devices not so much.
 
 I've seen a tube with the fins so hot that
 the solder was in globs, while
 the
 transmitter was still operating. I doubt any solid state
 final would
 have survived that heat.
 
 When we installed our solid
 state TV transmitter, it was a new learning
 curve in cooling. Both transmitters were 30 kW
 class AB1. The tube
 transmitter moved air
 faster through 3 tubes but had almost 3 times the
 temperature rise than the specs for the solid
 state transmitter. Our HVAC
 company and
 architect worked on several complex systems with air mixers
 
 until we just decided to use wall mounted
 air conditioners into the room
 behind the
 transmitter racks and exhausted to the front of the
 transmitters.
 
 Our solid
 state transmitter did meet the OSHA limit for 8 hours
 exposure to
 noise but just barely. It was
 very noisy compared to the tube unit.
 
 No tube transmitter I have ever used had a
 temperature shut down on any of
 the tube
 stages.
 
 73 George AI4VZ
 
 
 
 -----Original Message-----
 From: Don Wilhelm
 
 Only one bit of correction.  If the output
 power is 1500 watts and the
 efficiency is
 50%, that 1500 watts is only half the total power
 consumed, so there is 1500 watts of power that
 must be exhausted as heat.
 
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Re: KPA-1500 Fan Noise - YouTube ?

Edward R Cole
In reply to this post by Richard Thorne-4
Ah, yes ... the desert.  Land of rattlesnakes, hairy spiders, and
horny toads.  We got none of them in Alaska, absolutely no snakes of
any flavor, only garden spiders, and only the goldminers are h***.

Enough rain to never water the lawn.  We got snow, too!!

I lived on the edge of the Mojave in Barstow, CA so know the desert.

Tuscon is a nice town; visited in 1997.

73, Ed - KL7UW

From: Wes Stewart <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?

What's a basement?? On towertalk they talk about letting the lawn grow over
ground radials.? I wonder what a lawn is.? They also say to install
ground rods
where the rain will hit them.? I wonder what rain is.

Wes? N7WS


73, Ed - KL7UW
   http://www.kl7uw.com
Dubus-NA Business mail:
   [hidden email]  

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Re: KPA-1500 Fan Noise - YouTube ?

N2TK
In reply to this post by Gmail - George
George, there is nothing like Eimac Orange with a glass bottle. RF sunburn
:-)

Hey, transistors can run pretty hot too, although they should not melt the
solder. Case temp can get to 150 deg C and junction temp to 225 deg C. Yes
your finger will burn on the case. And yes, the life of many power devices
gets derated based on junction temp. As an example  an LDMOS may have an
MTTF of 1M hours at 150C and 70K hours at 225C junction temp. JANS space
transistors are burned in at 220C and tested up to 125C case temp.

N2TK, Tony

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Gmail - George
Sent: Saturday, June 02, 2018 8:10 AM
To: [hidden email]
Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?

One other thought to keep in mind - solid state amps need a lower delta T
than tube amps. Tubes like to run hot - solid state devices not so much.

I've seen a tube with the fins so hot that the solder was in globs, while
the transmitter was still operating. I doubt any solid state final would
have survived that heat.

When we installed our solid state TV transmitter, it was a new learning
curve in cooling. Both transmitters were 30 kW class AB1. The tube
transmitter moved air faster through 3 tubes but had almost 3 times the
temperature rise than the specs for the solid state transmitter. Our HVAC
company and architect worked on several complex systems with air mixers
until we just decided to use wall mounted air conditioners into the room
behind the transmitter racks and exhausted to the front of the transmitters.

Our solid state transmitter did meet the OSHA limit for 8 hours exposure to
noise but just barely. It was very noisy compared to the tube unit.

No tube transmitter I have ever used had a temperature shut down on any of
the tube stages.

73 George AI4VZ



-----Original Message-----
From: Don Wilhelm

Only one bit of correction.  If the output power is 1500 watts and the
efficiency is 50%, that 1500 watts is only half the total power consumed, so
there is 1500 watts of power that must be exhausted as heat.

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