Date   
Re: KPA-1500 sonics

dalej
 

How about rubber isolators mounts for the fan.  They are available from computer stores and Jameco.  The mount in the chassis holes for the fan then the other end mounts in the fan mount holes, they isolate the fan from the chassis.  

However if it’s just air noise that is a different situation.

Dale, K9VUJ



On 02, Aug 2018, at 9:17, Drew Vonada-Smith K3PA <drew@...> wrote:

Unfortunately, isolation of the chassis does not help.  The sonics are via air.

Remoting is great if you can...I am already in a basement with limited room.  A desktop device should be able to be on the desktop.  IMHO, putting the UI on the power supply and remoting the RF deck would have been a better desktop design choice.  Moving data between boxes is trivial, much easier than sonic improvement.

73,

Drew K3PA


Re: K3 vs K3s sensitivity and noise comparison

Michael Kopec
 

To Rob NC0B.  In response to your for feedback using K3s preamp #2.  I live in a metropolitan area but enjoy a fairly low noise level.  On 6m I find the #2 preamp almost indispensable  and use it 80+% of the time comparing it to pre amp Off and pre amp #  ON. 10m 12m I use it abt   20% of the time.  I primarily work CW and chase DX on 6M.  However this past two seasons due to DX stns going to FT8 I hve been less successful, My 6m set up is minimal, K3s, KPA500 amp, 2el Moxon at 27 ft. (HOA)  54 countries, 49 states confirmed since 2015.  de Mike K8NS

On Thursday, August 2, 2018, 11:58:44 AM EDT, Rob Sherwood <rob@...> wrote:


The noise floor of the K3 without the preamp has improved from the original value as seen from the 2008 data on my website.  Now preamp 1 on a K3S has only a modest noise floor reduction.  Preamp 2 in a K3S may be useful on 6 meters and 10 meters in a quiet location. Preamp 2 on 12 or 15 meters may be overkill even in a quiet location.  If you look at all the footnotes of all the K3s on my website you can see the effect of the different noise floors over the past 10 years with and without preamp(s).

Feedback from K3S owners as to the improvement from using Preamp 2 on 6 and 10 meters in quiet locations would be appreciated.  I don’t have access to a K3S at this time.  

Rob, NC0B


On Aug 2, 2018, at 5:37 AM, Marko via Groups.Io <reston2010mm-orders@...> wrote:

For those who own both, it'd be great to hear more on the K3s' ability to copy the weakest of signals, perhaps better than it's younger brother, the K3. Keeping the many parameter configurations the same for both, of course. 
No difference? 
Any differences noticed with the very weak data mode signals?
Is the lower phase noise in the K3s at all noticeable with weak signals?

/Mark

If this email is spam, report it to www.OnlyMyEmail.com

Re: K3 vs K3s sensitivity and noise comparison

Rob Sherwood
 

The noise floor of the K3 without the preamp has improved from the original value as seen from the 2008 data on my website.  Now preamp 1 on a K3S has only a modest noise floor reduction.  Preamp 2 in a K3S may be useful on 6 meters and 10 meters in a quiet location. Preamp 2 on 12 or 15 meters may be overkill even in a quiet location.  If you look at all the footnotes of all the K3s on my website you can see the effect of the different noise floors over the past 10 years with and without preamp(s).

Feedback from K3S owners as to the improvement from using Preamp 2 on 6 and 10 meters in quiet locations would be appreciated.  I don’t have access to a K3S at this time.  

Rob, NC0B


On Aug 2, 2018, at 5:37 AM, Marko via Groups.Io <reston2010mm-orders@...> wrote:

For those who own both, it'd be great to hear more on the K3s' ability to copy the weakest of signals, perhaps better than it's younger brother, the K3. Keeping the many parameter configurations the same for both, of course. 
No difference? 
Any differences noticed with the very weak data mode signals?
Is the lower phase noise in the K3s at all noticeable with weak signals?

/Mark

If this email is spam, report it to www.OnlyMyEmail.com

Re: KPA-1500 sonics

Drew Vonada-Smith K3PA
 

Charlie,

That is only true if they are moving less air.  There is already speed control on these fans, though it is a suboptimal implementation.  Their small diameter and high velocity of air is the cause...

Re: KPA-1500 sonics

Drew Vonada-Smith K3PA
 

Unfortunately, isolation of the chassis does not help.  The sonics are via air.

Remoting is great if you can...I am already in a basement with limited room.  A desktop device should be able to be on the desktop.  IMHO, putting the UI on the power supply and remoting the RF deck would have been a better desktop design choice.  Moving data between boxes is trivial, much easier than sonic improvement.

73,

Drew K3PA

Re: KPA-1500 sonics

Drew Vonada-Smith K3PA
 

I'm sure liquid cooling would be a design challenge in several ways but it is by no means ridiculous.

Re: KPA-1500 sonics

Drew Vonada-Smith K3PA
 

Roger on the call LOL.  Well, it is such a good amp tjherwise that I am not *TOO* dissapointed, but I do need it to be better for contest service, especially on SSB where the noise will probably get into the mic a bit.  If it were terrible, I'd just return it.  The problem is that is is good enough to want to keep, but has a "wart"...

Unusable is of course in the eyes of the user.  But the average guy would find this very noisy when run heavily.

It is quieter at lower power as you note...but not dramatically so, and I do need it for legal limit contest service...my goal is to be fully competitive.

73,

Drew K3PA

Re: KPA-1500 sonics

Drew Vonada-Smith K3PA
 

Chuck,

That is quite true and a good point, but it is responsible for perhaps a 2x factor at most.  I am talking about an amp more like 20 or 30 dB noisier than my ACOM.

73,

Drew K3PA

Re: KPA-1500 sonics

Drew Vonada-Smith K3PA
 

That how it is, but that's not how it has to be.  SS heat sinks can be designed to have lower velocity airflow over a quiet path also.

73,

Drew K3PA

Re: K3 output power erratic

Mark W2OR
 

Really good to hear that news, Steve.   Next IOTA you'll be out in front of the pack.

I'd like to hear more on how those two diodes should be tested, as well as cautions on how they should not be tested.  Thanks in advance.

Some improvement here re the K3 output levels.  Still not as stable as it used to be, but tolerable when using an amp, while following the manual's settings for minimal ALC.  I first did Tx Gain calibration test.  The results showed no issues present.  Then did a reset of the configurations / parameters, using the instructions in the manual.  Followed by a re-load of the former (saved) config parameters.  Followed by a re-set of the CONFIG: RS232 speed to its prior setting.  (The reload of the saved config settings did not re-set the former speed on its own.)   Things have calmed down since then.  Am still doing some OTA tests.  We'll see.

Yes, the support from the Elecraft support team is first-rate.  I have many great things to say about them.  Yes, they're awfully busy.  And sometimes you have to nudge the customer support team to get the opinion and recommendations from one of the engineers.  We're lucky to have them all in the loop.  

GL with your unit there.  Let me know if the testing and replacement process for those diodes was difficult.  Tks.  // Mark

K3 vs K3s sensitivity and noise comparison

Mark W2OR
 

For those who own both, it'd be great to hear more on the K3s' ability to copy the weakest of signals, perhaps better than it's younger brother, the K3. Keeping the many parameter configurations the same for both, of course. 
No difference? 
Any differences noticed with the very weak data mode signals?
Is the lower phase noise in the K3s at all noticeable with weak signals?

/Mark

Re: KPA-1500 sonics, Overheating, Related KPA1500 Issues

Mark W2OR
 

Noise:  Some good ideas on this thread about how to lower the noise level.   Hope to see more on this.

Overheating & Odor:  Something had overheated inside the KPA1500 here a few weeks ago.  The odor was obvious.  It came after having operated RTTY and when the fan was at level '2 or '3 of the five levels.   Long story as to the troubleshooting efforts in the days that followed, with Elecraft's expert assistance.  I'll spare you the details.  In short, certain parts had been overstressed and needed upgrading or replacement. 

Now, this early-production unit here is up and running once again.

It'd be good to hear about other 'issues' with the KPA1500, as they arise.  I like this amp, and I like its little brother, the KPA500.    //  w2or
 

Re: K3 output power erratic

Stephen Malyszka
 

Thanks for the info Mark but the issues you identified are the not the problem with my K3 SN6633.

I couldn't operate in the IOTA contest this past weekend so I did some troubleshooting. I found diode D1 on the K3LPA board defective. I contacted Elecraft and as usual... a very quick
and helpful response from them.  That company is amazing! They recommended replacing the diode, Q3 and Q6 as a set based on their history. This must be a common problem. I ordered
parts today so I'll let the group know the outcome after replacement. My K3 has been operational for 6 years and I'm not sure why this particular part failed. The only operational change I've
made during this period is operating mostly FT8 (since September 2017). Perhaps that has something to do with it.

Steve
AG2J

Re: K3 output power erratic

Mark W2OR
 

It'd be quite helpful to get more feedback on this topic, as to what the root causes have been, and their solutions.

Five years ago, replacement of a few parts in the KAT3 tuner inside the K3 solved the immediate problem of erratic power output.  Elecraft had a ready-to-send upgrade kit for that mod - - replacement of a cap or two, and a coil IF frequencies.  I forget if they charged for the kit, or not.

Another ham had a K3 preamp board replaced.

Here below are excerpts from a post at the other Groups.io  Elecraft listserve, that discusses the same issue.  Good luck and keep us posted. / mm  w2or

~~~

     There are (several) possible causes of erratic output power from the K3.  It’s always best to put together a long, detailed email report to Elecraft and let their techs check it out, based on the report, from there.  The more detail, the better.  They like, and appreciate, detail.  They’ll send back some troubleshooting tips and get to the bottom of it all.

      When you send them your report, and if you can, also include a copy of the K3 Utilities report from a recent Tx Gain Calibration procedure.  The report’s numbers and other data contained therein help the techs in their evaluation.  Make sure you use a good dummy load for the tests, with a short coax connection. 
      Among the possible causes of erratic output . . .  arcing or shorting within coax connections; or inside external tuners; or at the antenna connections; or within external amplifier SO-239 jacks . . . 

       Another possible cause of erratic output is the ALC setting in the K3 in CONFIG, or related settings . . .  Likewise the connections to any connected amplifier, even if the amp is 'OFF' . . .  Read, and re-read the Elecraft manuals re ALC settings.  If you think the settings are already set to the 'DEFAULT' settings, check them again.   BTW, the K3 Owners Manual here has eight separate pages that mentioned . . . ALC settings and connections.  (Check the latest manual renditions and suggestions, available at Elecraft.com)   The two main K3 configurations are for CONFIG: EXT ALC and CONFIG: TX ALC.   If you operate on 6m, make sure the configs there are correct, as they can often be band-specific.   As usual, Elecraft Support has good answers to most all your questions.

      Let us know how it all turns out.   73 de Mark w2or.

 

Post Script:  In ten years with two K3s, I’ve replaced three boards due to erratic output.  Two of them were the antenna tuner boards.  One of the two ATU boards had mods installed, including the IF choke coil and related caps.  Those mod kits are available from Elecraft. Depending on your K3 serial number, they may be supplied at no cost, and then again, maybe not.  Depends.  And as stated above, there are several other possible causes of erratic output. 

 

Re: KPA-1500 sonics

N2TK, Tony
 

Hi Dale,

My amps are in the basement on a shelf near the ceiling right below my feet in the shack. So the noise doesn’t bother me. Just making a suggestion about a possible lowering of the noise for those that have the amp in their shack.

73,

N2TK, Tony

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of dalej via Groups.Io
Sent: Tuesday, July 31, 2018 8:07 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA-1500 sonics

 

I don’t believe that would be wise.  It might disrupt the flow of air over the heatsink.  I would stick with the factory design and figure out a way of mounting the box on rubber isolators and or remoting it to a different location, under desk or even in another room.  Basement?  It’s designed for remoting so why not.  

 

Dale, k9vuj

 

 

On 31, Jul 2018, at 6:59, N2TK, Tony <tony.kaz@...> wrote:

 

Has anyone tried putting a pair of muffin fans on the top to suck out air? Maybe run at ½ or 2/3 speed so that they remain quiet. Would this give you more headroom before the  backside fans go into high speed?

N2TK, Tony

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Jeff AC0C
Sent: Tuesday, July 31, 2018 5:45 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA-1500 sonics

 

If you use the 1500 on SSB, you probably are not going to thing the noise is an issue.  The duty cycle of even compressed SSB is minimal on a time averaged basis.  

On the other hand, get into a serious CW rag chew where you are going back and forth at speed and it's easy to get the amp to hang in fan speed 2 with pops up to 3 pretty frequently.  If you are running RTTY (and I assume FT8, etc), then fan speed 3+ is where you are living a good portion of the time, depending on the room temp, with sSome bands and some load matches seeming to exacerbate the issue.

Comparison by owners of the '500 is not applicable as we are talking about apples and oranges in that case.  The thermals are unique to each of the two beasties.  The 1500 needs to off load about 1500W of heat at 50% efficiency - that's about the same heat as a portable room heater throws off so it's a significant thermal venting requirement.

A tube amp may run a bit higher efficiency (thus less waste heat to vent) but regardless of seal temps as mentioned by some observers, the waste heat has to be pulled off at a rate equal to the generation or the tube will continue to climb in temp.  So from that sense, the heat management comparison is a mostly fair one to make.  

While the comments about the tube amps are not exactly the same issues, those comments are aimed at simply pointing out that the best in class tube implementations (e.g. Acom 2000A) use a continually variable fan speed that smoothly ramps up and down based on the thermal needs of the amp.  The KPA 1500 by contrast jumps from level to level - with each change in speed catching one's attention at each speed change making the user experience less than what it could be with a smoothly variable speed method. 

I suppose the point I and perhaps some of the other new owners of this otherwise FB amp are making is that the fan speed implementation as it stands now - using the discrete level speeds - does not seem to live up to what would be reasonably be expected from the well deserved Elecraft reputation for nailing down the nits.  Especially given the polish the amp shows in most other aspects.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 31-Jul-18 12:20 PM, W2XJ wrote:

No, we’re talking about absurd expectations of desktop equipment. If gamers can liquid cool their cpus then extreme noise freaks can afford liquid cooled amplifiers. It’s not like the 60s or even the 80s. 


On Jul 30, 2018, at 21:05, Wes <wes@...> wrote:

Don't be ridiculous.  We are talking about desktop equipment here.  

I have experience with liquid cooled transmitters dating from the 1960-1980s.  AIM-54A Phoenix Missile used a silicon-based coolant that conditioned the klystron, power grid modulator and pulse transformer (it was used for its dielectric strength.). It also was run through coldwalls where a lot of other chassis were mounted. The oil circulated through the missile, through the umbilical to the launcher mounted on the F-14, through the wings to the fuselage where a heatpump conditioned it.

Later improvements in the AIM-54C "sealed" the missile and removed the circulation system.  But there ain't no free lunch. Aerodynamic heating of the missile limited the airspeed of the F-14.


On 7/30/2018 3:15 PM, W2XJ wrote:

 Not really since the heat exchanger is in a different location. Usually outside. Liquid is more efficient in removing heat from the heat sink.  We have 7 100KW liquid cooled solid state TV transmitters here in NYC atop WTC1. They are all in the same room and the room is nearly dead quiet. 


On Jul 30, 2018, at 14:36, Wes <wes@...> wrote:

Unless you have a supply of distilled water that you can dump down the drain after it gets hot, then you have to cool it off by rejecting the heat someplace else; usually into the air.   Then you've some full circle.

Wes  N7WS

 

 

 

Re: KPA-1500 sonics

Charlie T, k3ICH
 

I have found that many brands of “muffin” fans rated for 240VAC will run very quietly on 120VAC.

Conversely, wire two 120VAC fans in series for the same results.

 

I use a couple smaller fans like this on a Stereo unit in a cabinet.  It has run fine for over ten years.

I pull it out every five years or so and blow out any accumulated dust, but it must be removing enough heat to keep it running OK.

 

73, Charlie k3ICH

 

 

 

 

From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of N2TK, Tony
Sent: Tuesday, July 31, 2018 8:00 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA-1500 sonics

 

Has anyone tried putting a pair of muffin fans on the top to suck out air? Maybe run at ½ or 2/3 speed so that they remain quiet. Would this give you more headroom before the  backside fans go into high speed?

N2TK, Tony

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Jeff AC0C
Sent: Tuesday, July 31, 2018 5:45 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA-1500 sonics

 

If you use the 1500 on SSB, you probably are not going to thing the noise is an issue.  The duty cycle of even compressed SSB is minimal on a time averaged basis. 

On the other hand, get into a serious CW rag chew where you are going back and forth at speed and it's easy to get the amp to hang in fan speed 2 with pops up to 3 pretty frequently.  If you are running RTTY (and I assume FT8, etc), then fan speed 3+ is where you are living a good portion of the time, depending on the room temp, with sSome bands and some load matches seeming to exacerbate the issue.

Comparison by owners of the '500 is not applicable as we are talking about apples and oranges in that case.  The thermals are unique to each of the two beasties.  The 1500 needs to off load about 1500W of heat at 50% efficiency - that's about the same heat as a portable room heater throws off so it's a significant thermal venting requirement.

A tube amp may run a bit higher efficiency (thus less waste heat to vent) but regardless of seal temps as mentioned by some observers, the waste heat has to be pulled off at a rate equal to the generation or the tube will continue to climb in temp.  So from that sense, the heat management comparison is a mostly fair one to make. 

While the comments about the tube amps are not exactly the same issues, those comments are aimed at simply pointing out that the best in class tube implementations (e.g. Acom 2000A) use a continually variable fan speed that smoothly ramps up and down based on the thermal needs of the amp.  The KPA 1500 by contrast jumps from level to level - with each change in speed catching one's attention at each speed change making the user experience less than what it could be with a smoothly variable speed method.

I suppose the point I and perhaps some of the other new owners of this otherwise FB amp are making is that the fan speed implementation as it stands now - using the discrete level speeds - does not seem to live up to what would be reasonably be expected from the well deserved Elecraft reputation for nailing down the nits.  Especially given the polish the amp shows in most other aspects.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 31-Jul-18 12:20 PM, W2XJ wrote:

No, we’re talking about absurd expectations of desktop equipment. If gamers can liquid cool their cpus then extreme noise freaks can afford liquid cooled amplifiers. It’s not like the 60s or even the 80s. 


On Jul 30, 2018, at 21:05, Wes <wes@...> wrote:

Don't be ridiculous.  We are talking about desktop equipment here. 

I have experience with liquid cooled transmitters dating from the 1960-1980s.  AIM-54A Phoenix Missile used a silicon-based coolant that conditioned the klystron, power grid modulator and pulse transformer (it was used for its dielectric strength.). It also was run through coldwalls where a lot of other chassis were mounted. The oil circulated through the missile, through the umbilical to the launcher mounted on the F-14, through the wings to the fuselage where a heatpump conditioned it.

Later improvements in the AIM-54C "sealed" the missile and removed the circulation system.  But there ain't no free lunch. Aerodynamic heating of the missile limited the airspeed of the F-14.


On 7/30/2018 3:15 PM, W2XJ wrote:

 Not really since the heat exchanger is in a different location. Usually outside. Liquid is more efficient in removing heat from the heat sink.  We have 7 100KW liquid cooled solid state TV transmitters here in NYC atop WTC1. They are all in the same room and the room is nearly dead quiet. 


On Jul 30, 2018, at 14:36, Wes <wes@...> wrote:

Unless you have a supply of distilled water that you can dump down the drain after it gets hot, then you have to cool it off by rejecting the heat someplace else; usually into the air.   Then you've some full circle.

Wes  N7WS

 

 

Re: KPA-1500 sonics

dalej
 

I don’t believe that would be wise.  It might disrupt the flow of air over the heatsink.  I would stick with the factory design and figure out a way of mounting the box on rubber isolators and or remoting it to a different location, under desk or even in another room.  Basement?  It’s designed for remoting so why not.  

Dale, k9vuj


On 31, Jul 2018, at 6:59, N2TK, Tony <tony.kaz@...> wrote:

Has anyone tried putting a pair of muffin fans on the top to suck out air? Maybe run at ½ or 2/3 speed so that they remain quiet. Would this give you more headroom before the  backside fans go into high speed?
N2TK, Tony
 
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Jeff AC0C
Sent: Tuesday, July 31, 2018 5:45 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA-1500 sonics
 

If you use the 1500 on SSB, you probably are not going to thing the noise is an issue.  The duty cycle of even compressed SSB is minimal on a time averaged basis.  

On the other hand, get into a serious CW rag chew where you are going back and forth at speed and it's easy to get the amp to hang in fan speed 2 with pops up to 3 pretty frequently.  If you are running RTTY (and I assume FT8, etc), then fan speed 3+ is where you are living a good portion of the time, depending on the room temp, with sSome bands and some load matches seeming to exacerbate the issue.

Comparison by owners of the '500 is not applicable as we are talking about apples and oranges in that case.  The thermals are unique to each of the two beasties.  The 1500 needs to off load about 1500W of heat at 50% efficiency - that's about the same heat as a portable room heater throws off so it's a significant thermal venting requirement.

A tube amp may run a bit higher efficiency (thus less waste heat to vent) but regardless of seal temps as mentioned by some observers, the waste heat has to be pulled off at a rate equal to the generation or the tube will continue to climb in temp.  So from that sense, the heat management comparison is a mostly fair one to make.  

While the comments about the tube amps are not exactly the same issues, those comments are aimed at simply pointing out that the best in class tube implementations (e.g. Acom 2000A) use a continually variable fan speed that smoothly ramps up and down based on the thermal needs of the amp.  The KPA 1500 by contrast jumps from level to level - with each change in speed catching one's attention at each speed change making the user experience less than what it could be with a smoothly variable speed method. 

I suppose the point I and perhaps some of the other new owners of this otherwise FB amp are making is that the fan speed implementation as it stands now - using the discrete level speeds - does not seem to live up to what would be reasonably be expected from the well deserved Elecraft reputation for nailing down the nits.  Especially given the polish the amp shows in most other aspects.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 31-Jul-18 12:20 PM, W2XJ wrote:

No, we’re talking about absurd expectations of desktop equipment. If gamers can liquid cool their cpus then extreme noise freaks can afford liquid cooled amplifiers. It’s not like the 60s or even the 80s. 


On Jul 30, 2018, at 21:05, Wes <wes@...> wrote:

Don't be ridiculous.  We are talking about desktop equipment here.  

I have experience with liquid cooled transmitters dating from the 1960-1980s.  AIM-54A Phoenix Missile used a silicon-based coolant that conditioned the klystron, power grid modulator and pulse transformer (it was used for its dielectric strength.). It also was run through coldwalls where a lot of other chassis were mounted. The oil circulated through the missile, through the umbilical to the launcher mounted on the F-14, through the wings to the fuselage where a heatpump conditioned it.

Later improvements in the AIM-54C "sealed" the missile and removed the circulation system.  But there ain't no free lunch. Aerodynamic heating of the missile limited the airspeed of the F-14.


On 7/30/2018 3:15 PM, W2XJ wrote:

 Not really since the heat exchanger is in a different location. Usually outside. Liquid is more efficient in removing heat from the heat sink.  We have 7 100KW liquid cooled solid state TV transmitters here in NYC atop WTC1. They are all in the same room and the room is nearly dead quiet. 


On Jul 30, 2018, at 14:36, Wes <wes@...> wrote:

Unless you have a supply of distilled water that you can dump down the drain after it gets hot, then you have to cool it off by rejecting the heat someplace else; usually into the air.   Then you've some full circle.

Wes  N7WS
 
 


Re: KPA-1500 sonics

N2TK, Tony
 

Has anyone tried putting a pair of muffin fans on the top to suck out air? Maybe run at ½ or 2/3 speed so that they remain quiet. Would this give you more headroom before the  backside fans go into high speed?

N2TK, Tony

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Jeff AC0C
Sent: Tuesday, July 31, 2018 5:45 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA-1500 sonics

 

If you use the 1500 on SSB, you probably are not going to thing the noise is an issue.  The duty cycle of even compressed SSB is minimal on a time averaged basis. 

On the other hand, get into a serious CW rag chew where you are going back and forth at speed and it's easy to get the amp to hang in fan speed 2 with pops up to 3 pretty frequently.  If you are running RTTY (and I assume FT8, etc), then fan speed 3+ is where you are living a good portion of the time, depending on the room temp, with sSome bands and some load matches seeming to exacerbate the issue.

Comparison by owners of the '500 is not applicable as we are talking about apples and oranges in that case.  The thermals are unique to each of the two beasties.  The 1500 needs to off load about 1500W of heat at 50% efficiency - that's about the same heat as a portable room heater throws off so it's a significant thermal venting requirement.

A tube amp may run a bit higher efficiency (thus less waste heat to vent) but regardless of seal temps as mentioned by some observers, the waste heat has to be pulled off at a rate equal to the generation or the tube will continue to climb in temp.  So from that sense, the heat management comparison is a mostly fair one to make. 

While the comments about the tube amps are not exactly the same issues, those comments are aimed at simply pointing out that the best in class tube implementations (e.g. Acom 2000A) use a continually variable fan speed that smoothly ramps up and down based on the thermal needs of the amp.  The KPA 1500 by contrast jumps from level to level - with each change in speed catching one's attention at each speed change making the user experience less than what it could be with a smoothly variable speed method.

I suppose the point I and perhaps some of the other new owners of this otherwise FB amp are making is that the fan speed implementation as it stands now - using the discrete level speeds - does not seem to live up to what would be reasonably be expected from the well deserved Elecraft reputation for nailing down the nits.  Especially given the polish the amp shows in most other aspects.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 31-Jul-18 12:20 PM, W2XJ wrote:

No, we’re talking about absurd expectations of desktop equipment. If gamers can liquid cool their cpus then extreme noise freaks can afford liquid cooled amplifiers. It’s not like the 60s or even the 80s. 


On Jul 30, 2018, at 21:05, Wes <wes@...> wrote:

Don't be ridiculous.  We are talking about desktop equipment here. 

I have experience with liquid cooled transmitters dating from the 1960-1980s.  AIM-54A Phoenix Missile used a silicon-based coolant that conditioned the klystron, power grid modulator and pulse transformer (it was used for its dielectric strength.). It also was run through coldwalls where a lot of other chassis were mounted. The oil circulated through the missile, through the umbilical to the launcher mounted on the F-14, through the wings to the fuselage where a heatpump conditioned it.

Later improvements in the AIM-54C "sealed" the missile and removed the circulation system.  But there ain't no free lunch. Aerodynamic heating of the missile limited the airspeed of the F-14.


On 7/30/2018 3:15 PM, W2XJ wrote:

 Not really since the heat exchanger is in a different location. Usually outside. Liquid is more efficient in removing heat from the heat sink.  We have 7 100KW liquid cooled solid state TV transmitters here in NYC atop WTC1. They are all in the same room and the room is nearly dead quiet. 


On Jul 30, 2018, at 14:36, Wes <wes@...> wrote:

Unless you have a supply of distilled water that you can dump down the drain after it gets hot, then you have to cool it off by rejecting the heat someplace else; usually into the air.   Then you've some full circle.

Wes  N7WS

 

 

Serial Box web site updated with new KX3/KPA500 and RemoteHams connection examples

Bob Wilson, N6TV
 

I've added new sample schematics and block diagrams showing how my new Serial Box (S-BOX) could be used effectively with the Elecraft KX3 and KPA500 to provide automatic band changes, with no custom cables required.  It also illustrates how the S-BOX supports logger-generated CW keying over the DTR pin of the same serial port that is controlling the KX3 (something built-in to the K3 serial port, but not the KX3 or KX2).


Scroll down a bit and click on 

S-BOX Features and Wiring Examples

then click KX3 Docking Station.

For those using RemoteHams software with the K3 or K3S, there's a new diagram showing how one of my customers plans to use his new S-BOX to remotely power up and use his K3 with the RCForb client/server software (no RemoteRig box required).  It's a complex setup with a P3, FSK keying, a KPA1500 and a Hamation ShackMaster SM-8 antenna controller all working cooperatively through the S-BOX, while being controlled remotely.

I've also added new examples showing how to connect the K3/K3S (or any supported radio) to an ACOM or SPE amplifier with automatic band changes.  I plan to add one more showing how to connect any supported non-Elecraft radio to a KPA1500 through the S-BOX.

If you have a particular configuration where it is not obvious from the current examples and schematics how you would connect things, please send me your requirements (off line), and I'll see what I can come up with.

I've also simplified the S-BOX order form a bit.

73,
Bob, N6TV

Re: KPA-1500 sonics

Jeff AC0C
 

If you use the 1500 on SSB, you probably are not going to thing the noise is an issue.  The duty cycle of even compressed SSB is minimal on a time averaged basis. 

On the other hand, get into a serious CW rag chew where you are going back and forth at speed and it's easy to get the amp to hang in fan speed 2 with pops up to 3 pretty frequently.  If you are running RTTY (and I assume FT8, etc), then fan speed 3+ is where you are living a good portion of the time, depending on the room temp, with sSome bands and some load matches seeming to exacerbate the issue.

Comparison by owners of the '500 is not applicable as we are talking about apples and oranges in that case.  The thermals are unique to each of the two beasties.  The 1500 needs to off load about 1500W of heat at 50% efficiency - that's about the same heat as a portable room heater throws off so it's a significant thermal venting requirement.

A tube amp may run a bit higher efficiency (thus less waste heat to vent) but regardless of seal temps as mentioned by some observers, the waste heat has to be pulled off at a rate equal to the generation or the tube will continue to climb in temp.  So from that sense, the heat management comparison is a mostly fair one to make. 

While the comments about the tube amps are not exactly the same issues, those comments are aimed at simply pointing out that the best in class tube implementations (e.g. Acom 2000A) use a continually variable fan speed that smoothly ramps up and down based on the thermal needs of the amp.  The KPA 1500 by contrast jumps from level to level - with each change in speed catching one's attention at each speed change making the user experience less than what it could be with a smoothly variable speed method.

I suppose the point I and perhaps some of the other new owners of this otherwise FB amp are making is that the fan speed implementation as it stands now - using the discrete level speeds - does not seem to live up to what would be reasonably be expected from the well deserved Elecraft reputation for nailing down the nits.  Especially given the polish the amp shows in most other aspects.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 31-Jul-18 12:20 PM, W2XJ wrote:

No, we’re talking about absurd expectations of desktop equipment. If gamers can liquid cool their cpus then extreme noise freaks can afford liquid cooled amplifiers. It’s not like the 60s or even the 80s. 


On Jul 30, 2018, at 21:05, Wes <wes@...> wrote:

Don't be ridiculous.  We are talking about desktop equipment here. 

I have experience with liquid cooled transmitters dating from the 1960-1980s.  AIM-54A Phoenix Missile used a silicon-based coolant that conditioned the klystron, power grid modulator and pulse transformer (it was used for its dielectric strength.). It also was run through coldwalls where a lot of other chassis were mounted. The oil circulated through the missile, through the umbilical to the launcher mounted on the F-14, through the wings to the fuselage where a heatpump conditioned it.

Later improvements in the AIM-54C "sealed" the missile and removed the circulation system.  But there ain't no free lunch. Aerodynamic heating of the missile limited the airspeed of the F-14.


On 7/30/2018 3:15 PM, W2XJ wrote:
 Not really since the heat exchanger is in a different location. Usually outside. Liquid is more efficient in removing heat from the heat sink.  We have 7 100KW liquid cooled solid state TV transmitters here in NYC atop WTC1. They are all in the same room and the room is nearly dead quiet. 


On Jul 30, 2018, at 14:36, Wes <wes@...> wrote:

Unless you have a supply of distilled water that you can dump down the drain after it gets hot, then you have to cool it off by rejecting the heat someplace else; usually into the air.   Then you've some full circle.

Wes  N7WS