Topics

[Elecraft] KPA1500 vs SPE Amps

Paul Baldock
 

I owned an SPE 1.5K for 2 weeks, before sending it back.

It struggled to make 1500W. On 20M compression was 2dB, compared to about 1dB on the KPA1500. On 6M it maxed out at around 1.3KW. SPE recommend not running compression on phone. I can see why as after about 15 mins of operation it would cut back to"mid" power. I think if you considered it a 1KW amp and run it at that level then you would be happy. SPE amps do not meet the FCC specs for gain of < 15dB. Mine was around 21dB. A lot of their customers like this, but I specifically want mine at around 14-15dB so I could drive it with similar power to my ACOM2000. I did like the 2 rf inputs.

- Paul KW7Y

At 01:44 PM 2/12/2019, you wrote:
Has anyone had experience with both the KPA1500 and any of the current (1.3K, 1.5K or 2K) Expert Linears from SPE? I was initially leaning towards the 1.3K-FA without the ATU. The more I thought about it, the more I wanted to go with an ATU. The price difference to get less than 1db in going from 1300 watts to 1500 was also a bit of a concern. However, I’ve never pushed my 3x8874s to more than 1200 and only on the low bands. I have a KPA500 with the KAT500 and it’s great. However, in a 160 pileup a bit more power would help. Changing bands quickly is awesome. That has me leaning towards the KPA1500. If anyone would like to share their thoughts, it would be greatly appreciated. Also, I’m wondering if anyone has run their KPA500 and a KPA1500 off of the same K3? If so, how did you set it up? Tnx es 73, Dave N8AG Sent from Mail for Windows 10 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@... This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to paul@...

Drew Vonada-Smith K3PA
 

That SPE report sounds typical.  I believe the device only uses one LDMOS device, while the KPA1500 has two.  Though I gripe about the very loud fans on the KPA1500, it is otherwise a  good amplifier, at full legal limit contest service.  It is my 2nd amp, with the ACOM 2000 as primary.

73,

Drew K3PA

Stephen Bloom
 

A more valid comparison, in terms of both price point and performance would be the 2K-FA to the KPA1500.  As in the case of the 1.5K it is a single LDMOS device, though that LDMOS is more robust.  I have 2 2K-FAs and 1 1.5K-FA (had a 1.3K-FA which I sold).  All were bought either before the KPA1500 started shipping, or while the waiting list was months long.  The 2K-FA will comfortably run 1500W without getting super hot in non full duty cycle modes, but only 1200W in full duty cycle (such as RTTY).  The issue with single LDMOS vs. dual isn’t necessarily power output per se, but about IMD products.  Heavy duty operation at full power of a single LDMOS is pushing the envelope, but given the fact that the LDMOS in the 2K-FA is rated at 2KW or so, it seems acceptable. 

 

I’ve only used the 1.5K-FA a limited amount and also have found no issues getting 1.5KW out ..as a matter of fact, the firmware doesn’t seem to enforce the 1200W limit on RTTY, though I don’t recommend doing it.  The lower rated LDMOS and the smaller unit would have me hesitant to run it at full limit for 48 hours, but I have no reason other than general conservativeness in terms of amplifiers, even tube types.  I’m surprised you had trouble driving it to full power, but I basically concur that you should consider it as a 1000-1200W amp.  Also a reminder that the difference between 1000-1200 and 1500 is *very* marginal.

 

My intent for the 1.5K is to use it as a travel amp with a KX3, a lightweight kilowatt, though for now it has a position at the contest station.  When finances allow, I will probably buy a KPA1500 for that position.

 

As for having both KPA500 and 1500 in line, there is just no reason.  You don’t have to drive the KPA1500 to full limit.  At 500W, the fan won’t run much, so noise won’t be an issue.

 

73

Steve KL7SB

 

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Drew Vonada-Smith K3PA
Sent: Tuesday, February 12, 2019 4:25 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] [Elecraft] KPA1500 vs SPE Amps

 

That SPE report sounds typical.  I believe the device only uses one LDMOS device, while the KPA1500 has two.  Though I gripe about the very loud fans on the KPA1500, it is otherwise a  good amplifier, at full legal limit contest service.  It is my 2nd amp, with the ACOM 2000 as primary.

73,

Drew K3PA

Bill KO7SS
 

So on RTTY the frustration I have is the 2K-FA senses any key down > 2 second as continuous duty and puts the amp into medium duty 1 KW max output.

The amp gain is so high that 26 vs 27 watts drive can either be 1400W, triggering the change to medium duty 1 kW, or slightly less running at 1200W which is OK.

I want to 1500W HARD in a RTTY contest x 36+ hours and not get faults that that take me down to 1 KW. Do I need to get a KPA1500?

73 Bill KO7SS

Richard Williams
 

Bill,

I use the KPA1500 on RTTY; and yes, it will run 1500 watts on RTTY.   BUT, it is not rated for continuous duty (like my previous Alpha 9500).  It is ICAS rated with the following limitations:

100% ICAS for 100% duty cycle modulation modes (FM, RTTY, FT8, JT65, etc.)

 

1.8-30 MHz: Maximum 5 minutes key down / Minimum 5 minutes receive (after 5 minute TX)


This limitation has not bothered me.  I chase DX, and I am quite sure such operation is in the 50% or less transmit time to receive time.

If you are planning on transmitting a 10 min "brag tape" or send out ARRL bulletins on RTTY, I would not recommend the KPA1500.

would think contest operation would be within the 50/50 limit though.

Dick  K8ZTT 


On Sun, Nov 10, 2019 at 20:38, Bill KO7SS via Groups.Io
<ko7ss@...> wrote:
So on RTTY the frustration I have is the 2K-FA senses any key down > 2 second as continuous duty and puts the amp into medium duty 1 KW max output.

The amp gain is so high that 26 vs 27 watts drive can either be 1400W, triggering the change to medium duty 1 kW, or slightly less running at 1200W which is OK.

I want to 1500W HARD in a RTTY contest x 36+ hours and not get faults that that take me down to 1 KW. Do I need to get a KPA1500?


73 Bill KO7SS

Jeff AC0C
 

I measured the compression onset point at around 1100W.  1500W is roughly the 1db comp point.  The amp has no significant headroom but it's otherwise competent at the 1500W point from a power output standpoint.  I do not use the antenna tuner function and in looking at the component sizes there I would not care to speculate about the amount of loss at power - but I don't use it so it's not been a problem. 

The practical limitation on the KPA1500 is arguably more related to the human's ability to withstand the racket the fans make when it's rocking along.  I've run quite a number of RTTY contests now (no RTTY rag chew) and it's never got warm enough to trigger whatever I assume the safeguards on temp are.  But when it gets warm it will make a lot of noise.  And when it gets hot, it will literally scream.  If you have ever been in a colo or big computer server data center, you will know exactly what I mean.

Other than the noise, it's a fine amp.  Works as advertised and given the size of the box, you can understand why they have equipped it with a max fan capability that would credit a wind tunnel.

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


On 11/11/19 3:55 PM, Richard Williams via Groups.Io wrote:

Bill,

I use the KPA1500 on RTTY; and yes, it will run 1500 watts on RTTY.   BUT, it is not rated for continuous duty (like my previous Alpha 9500).  It is ICAS rated with the following limitations:

100% ICAS for 100% duty cycle modulation modes (FM, RTTY, FT8, JT65, etc.)

 

1.8-30 MHz: Maximum 5 minutes key down / Minimum 5 minutes receive (after 5 minute TX)


This limitation has not bothered me.  I chase DX, and I am quite sure such operation is in the 50% or less transmit time to receive time.

If you are planning on transmitting a 10 min "brag tape" or send out ARRL bulletins on RTTY, I would not recommend the KPA1500.

would think contest operation would be within the 50/50 limit though.

Dick  K8ZTT 


On Sun, Nov 10, 2019 at 20:38, Bill KO7SS via Groups.Io
So on RTTY the frustration I have is the 2K-FA senses any key down > 2 second as continuous duty and puts the amp into medium duty 1 KW max output.

The amp gain is so high that 26 vs 27 watts drive can either be 1400W, triggering the change to medium duty 1 kW, or slightly less running at 1200W which is OK.

I want to 1500W HARD in a RTTY contest x 36+ hours and not get faults that that take me down to 1 KW. Do I need to get a KPA1500?


73 Bill KO7SS