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KPA1500 duty cycle

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K7TV

KPA1500 duty cycle

A recent Elecraft newsletter stated that "the KPA1500 is a high duty cycle
amplifier compatible with most digital modes ranging from RTTY through JT65
etc.". The KPA1500 manual specifices for 50 MHz "Maximum 50 sec key down /
50 sec standby (Rec. Min Fan Speed set = 2)".

My question: For the 50 MHz scenario of alternating 50 sec carrier and 50
sec standby, how much testing has been done? Has anyone run this way for
days on end?

73,
Erik K7TV

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Eric Swartz - WA6HHQ

Re: KPA1500 duty cycle

Administrator

Hi Erik,

Yes, the amp can run indefinitely on 50 Mhz with 50 sec key down TX at
continuous 1500W carrier followed by 50 sec in RX. We specifically were looking
at 100% carrier modes like JT65 etc. when we conservatively specified this.

73,
Eric
/elecraft.com/

On 2/14/2018 11:07 AM, Erik Basilier wrote:

> A recent Elecraft newsletter stated that "the KPA1500 is a high duty cycle
> amplifier compatible with most digital modes ranging from RTTY through JT65
> etc.". The KPA1500 manual specifices for 50 MHz "Maximum 50 sec key down /
> 50 sec standby (Rec. Min Fan Speed set = 2)".
>
> My question: For the 50 MHz scenario of alternating 50 sec carrier and 50
> sec standby, how much testing has been done? Has anyone run this way for
> days on end?
>
> 73,
> Erik K7TV
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Jim Brown-10

Re: KPA1500 duty cycle

And even this is conservative -- JT65 is 48 sec TX and 72 sec RX, so 40%
duty cycle. FT8 and MSK144 have equal TX and RX times, so 50% duty
cycle. The TX period for MSK144 can be varied from 5-30 sec, but TX and
RX times are always equal.

73, Jim K9YC

On 2/14/2018 3:25 PM, Eric Swartz - WA6HHQ, Elecraft wrote:
> Yes, the amp can run indefinitely on 50 Mhz with 50 sec key down TX at
> continuous 1500W carrier followed by 50 sec in RX. We specifically
> were looking at 100% carrier modes like JT65 etc. when we
> conservatively specified this.

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KQ5S-Tom

Re: KPA1500 duty cycle

I believe FT8 is 13 sec TX, 2 sec decode and then 15 sec RX for a total of
17 sec non-TX so you have 13 sec TX and 17 sec RX. Much less than 50%.

-----------------
73,
Tom - KQ5S

On Wed, Feb 14, 2018 at 6:51 PM, Jim Brown <[hidden email]>
wrote:

> And even this is conservative -- JT65 is 48 sec TX and 72 sec RX, so 40%
> duty cycle. FT8 and MSK144 have equal TX and RX times, so 50% duty cycle.
> The TX period for MSK144 can be varied from 5-30 sec, but TX and RX times
> are always equal.
>
> 73, Jim K9YC
>
> On 2/14/2018 3:25 PM, Eric Swartz - WA6HHQ, Elecraft wrote:
>
>> Yes, the amp can run indefinitely on 50 Mhz with 50 sec key down TX at
>> continuous 1500W carrier followed by 50 sec in RX. We specifically were
>> looking at 100% carrier modes like JT65 etc. when we conservatively
>> specified this.
>>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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>

Dennis Moore

Re: KPA1500 duty cycle

Specification is 13.48 sec TX, 16.52 sec RX, 45% Duty Cycle.

Source: http://qrznow.com/new-digital-mode-from-k1jt-ft8/

73, Dennis NJ6G

On 2/14/2018 17:07, Tom-KQ5S wrote:

> I believe FT8 is 13 sec TX, 2 sec decode and then 15 sec RX for a total of
> 17 sec non-TX so you have 13 sec TX and 17 sec RX. Much less than 50%.
>
> -----------------
> 73,
> Tom - KQ5S
>
> On Wed, Feb 14, 2018 at 6:51 PM, Jim Brown <[hidden email]>
> wrote:
>
>> And even this is conservative -- JT65 is 48 sec TX and 72 sec RX, so 40%
>> duty cycle. FT8 and MSK144 have equal TX and RX times, so 50% duty cycle.
>> The TX period for MSK144 can be varied from 5-30 sec, but TX and RX times
>> are always equal.
>>
>> 73, Jim K9YC

Richard Lamont

Re: KPA1500 duty cycle

In reply to this post by K7TV

The FT8 parameters were tweaked slightly during the beta phase prior to
the release of WSJT-X 1.8.0, and the TX time was reduced to 12.64 sec,
so the duty cycle is now about 42%.

73,
Richard G4DYA

On 15/02/18 01:22, Dennis Moore wrote:

> Specification is 13.48 sec TX, 16.52 sec RX, 45% Duty Cycle.
>
> Source: http://qrznow.com/new-digital-mode-from-k1jt-ft8/
>
> 73, Dennis NJ6G
>
>
> On 2/14/2018 17:07, Tom-KQ5S wrote:
>> I believe FT8 is 13 sec TX, 2 sec decode and then 15 sec RX for a
>> total of
>> 17 sec non-TX so you have 13 sec TX and 17 sec RX. Much less than 50%.
>>
>> -----------------
>> 73,
>> Tom - KQ5S
>>
>> On Wed, Feb 14, 2018 at 6:51 PM, Jim Brown <[hidden email]>
>> wrote:
>>
>>> And even this is conservative -- JT65 is 48 sec TX and 72 sec RX, so 40%
>>> duty cycle. FT8 and MSK144 have equal TX and RX times, so 50% duty
>>> cycle.
>>> The TX period for MSK144 can be varied from 5-30 sec, but TX and RX
>>> times
>>> are always equal.
>>>
>>> 73, Jim K9YC

Eric Swartz - WA6HHQ

Re: KPA1500 duty cycle

Administrator

Easy to handle for the 1500 on any band. :-)

73,
Eric
/elecraft.com/

On 2/15/2018 12:51 AM, Richard Lamont wrote:

> The FT8 parameters were tweaked slightly during the beta phase prior to
> the release of WSJT-X 1.8.0, and the TX time was reduced to 12.64 sec,
> so the duty cycle is now about 42%.
>
> 73,
> Richard G4DYA
>
> On 15/02/18 01:22, Dennis Moore wrote:
>> Specification is 13.48 sec TX, 16.52 sec RX, 45% Duty Cycle.
>>
>> Source: http://qrznow.com/new-digital-mode-from-k1jt-ft8/
>>
>> 73, Dennis NJ6G
>>
>>
>> On 2/14/2018 17:07, Tom-KQ5S wrote:
>>> I believe FT8 is 13 sec TX, 2 sec decode and then 15 sec RX for a
>>> total of
>>> 17 sec non-TX so you have 13 sec TX and 17 sec RX. Much less than 50%.
>>>
>>> -----------------
>>> 73,
>>> Tom - KQ5S
>>>
>>> On Wed, Feb 14, 2018 at 6:51 PM, Jim Brown <[hidden email]>
>>> wrote:
>>>
>>>> And even this is conservative -- JT65 is 48 sec TX and 72 sec RX, so 40%
>>>> duty cycle. FT8 and MSK144 have equal TX and RX times, so 50% duty
>>>> cycle.
>>>> The TX period for MSK144 can be varied from 5-30 sec, but TX and RX
>>>> times
>>>> are always equal.
>>>>
>>>> 73, Jim K9YC
> ______________________________________________________________
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>
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