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K2 initial power ramp after band change

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Martin Sole-3

K2 initial power ramp after band change

Having a lot of fun in the AA CW test, even with my ropey CW using the
barefoot K2/10. Definitely the beam at 80 feet helps but still it's
great to be working JA and others on 21 and 28 MHz with just the 10
watts from my HS QTH. Since building the K2 it's been one of the first
times I've been able to put it through its paces and it is a lot of fun.

A quirk I've noticed, easy to work around, but I'm curious if its just
mine. After a band change the first dit, or two, is not at full power.
There seems to be an initial ramp up after which all is good and I don't
see any fluctuation in power. Supply is 13.5 volts when producing full
power, about 13.9 with just the receiver running. Full power current on
28Mhz is showing on the display as 2.66A. I can see the ramp up on the
bar graph, it shows one bar for the first 3-4 dots then ramps up to all
10 bars. I have confirmed the same with an external power meter.
Anything I can do about this?

Martin, HS0ZED

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John Oppenheimer

Re: K2 initial power ramp after band change

Hi Martin,

The power ramp up is normal behavior. The K2 uses requested power
control (Page 92, "Requested vs. Actual Power:" paragraph)

With a per band set value (Page 111, "Microcontroller" paragraph, "ALC,
which is used on CW to maintain the user-specified power level across
all bands.")

When changing bands, the output power is sampled by the microcontroller
resulting with a change in the transmitter ALC to increase power. The
ALC action requires a few dits or TUNE to complete.

John KN5L K2 #7212

On 06/17/2018 01:43 AM, Martin Sole wrote:
> After a band change the first dit, or two, is not at full power.
> There seems to be an initial ramp up after which all is good and I don't
> see any fluctuation in power. Supply is 13.5 volts when producing full
> power, about 13.9 with just the receiver running. Full power current on
> 28Mhz is showing on the display as 2.66A. I can see the ramp up on the
> bar graph, it shows one bar for the first 3-4 dots then ramps up to all
> 10 bars. I have confirmed the same with an external power meter.
> Anything I can do about this?
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Bob McGraw - K4TAX

Re: K2 initial power ramp after band change

I've noticed a bit of the same thing on my K3S. Not an issue but I
view as a nice safety feature preventing overshoot and over drive of my
KPA500.

73

Bob, K4TAX

On 6/17/2018 7:07 AM, John Oppenheimer wrote:

> Hi Martin,
>
> The power ramp up is normal behavior. The K2 uses requested power
> control (Page 92, "Requested vs. Actual Power:" paragraph)
>
> With a per band set value (Page 111, "Microcontroller" paragraph, "ALC,
> which is used on CW to maintain the user-specified power level across
> all bands.")
>
> When changing bands, the output power is sampled by the microcontroller
> resulting with a change in the transmitter ALC to increase power. The
> ALC action requires a few dits or TUNE to complete.
>
> John KN5L K2 #7212
>
> On 06/17/2018 01:43 AM, Martin Sole wrote:
>> After a band change the first dit, or two, is not at full power.
>> There seems to be an initial ramp up after which all is good and I don't
>> see any fluctuation in power. Supply is 13.5 volts when producing full
>> power, about 13.9 with just the receiver running. Full power current on
>> 28Mhz is showing on the display as 2.66A. I can see the ramp up on the
>> bar graph, it shows one bar for the first 3-4 dots then ramps up to all
>> 10 bars. I have confirmed the same with an external power meter.
>> Anything I can do about this?
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Don Wilhelm

Re: K2 initial power ramp after band change

In reply to this post by Martin Sole-3

Martin,

The K2 resets the power control mechanism after a band change or a
change in the POWER control. To prevent overshoot, it starts out low
and ramps up quickly to the requested power.
It must sense the actual power output and adjust the drive accordingly,
and that takes one or two dit times to happen.

73,
Don W3FPR

On 6/17/2018 2:43 AM, Martin Sole wrote:

> A quirk I've noticed, easy to work around, but I'm curious if its just
> mine. After a band change the first dit, or two, is not at full power.
> There seems to be an initial ramp up after which all is good and I don't
> see any fluctuation in power.
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John Oppenheimer

Re: K2 initial power ramp after band change

In reply to this post by Bob McGraw - K4TAX

Hi Bob,

The K3s, KX3, and KX2 use a similar ALC power control design.

John KN5L

On 06/17/2018 07:47 AM, Bob McGraw K4TAX wrote:

> I've noticed a bit of the same thing on my K3S. Not an issue but I
> view as a nice safety feature preventing overshoot and over drive of my
> KPA500.
>
> 73
>
> Bob, K4TAX
>
> On 6/17/2018 7:07 AM, John Oppenheimer wrote:
>> Hi Martin,
>>
>> The power ramp up is normal behavior. The K2 uses requested power
>> control (Page 92, "Requested vs. Actual Power:" paragraph)
>>
>> With a per band set value (Page 111, "Microcontroller" paragraph, "ALC,
>> which is used on CW to maintain the user-specified power level across
>> all bands.")
>>
>> When changing bands, the output power is sampled by the microcontroller
>> resulting with a change in the transmitter ALC to increase power. The
>> ALC action requires a few dits or TUNE to complete.
>>
>> John KN5L K2 #7212
>>
>> On 06/17/2018 01:43 AM, Martin Sole wrote:
>>> After a band change the first dit, or two, is not at full power.
>>> There seems to be an initial ramp up after which all is good and I don't
>>> see any fluctuation in power. Supply is 13.5 volts when producing full
>>> power, about 13.9 with just the receiver running. Full power current on
>>> 28Mhz is showing on the display as 2.66A. I can see the ramp up on the
>>> bar graph, it shows one bar for the first 3-4 dots then ramps up to all
>>> 10 bars. I have confirmed the same with an external power meter.
>>> Anything I can do about this?

Martin Sole-3

Re: K2 initial power ramp after band change

In reply to this post by John Oppenheimer

Thanks for all the replies. At least I know I'm normal, er, well the
radio is at least :)

Had a good time with AA CW test this weekend just in and out of the
shack an hour or two at a time and limiting myself to the K2 at 10 watts
whilst the K3 and big Alpha sit idle. Very good to work into EU with the
10 watts and completed with K3EST and K7QA both of whom have uuge!
signals here is SE Asia tonight but still my first 2 USA with 10 watts.
It's rare to hear US stations here and more so to hear them that strong.

Martin, HS0ZED

>> After a band change the first dit, or two, is not at full power.
>> There seems to be an initial ramp up after which all is good and I don't
>> see any fluctuation in power. Supply is 13.5 volts when producing full
>> power, about 13.9 with just the receiver running. Full power current on
>> 28Mhz is showing on the display as 2.66A. I can see the ramp up on the
>> bar graph, it shows one bar for the first 3-4 dots then ramps up to all
>> 10 bars. I have confirmed the same with an external power meter.
>> Anything I can do about this?
> ______________________________________________________________
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