K3 from 100W to QRP

[Benny Aumala]

Maybe my interest to QRP is partially because K2.
I want to use my K3/100 still quite a lot in QRP and QRPP.
The degree of adjust is really fine down to 0.1W.
Also, 100W PA switch-off below 10W is very clever.
But to crank between 100 and 5W is not very handy.

I would like to see PF1 to change powers between two adjustable levels.

Benny    oh9nb

 


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[Joe-aa4nn]

Benny, it's just the turn of a pot!
How difficult or inconvenient could that be.  hi
de Joe, aa4nn

----- Original Message -----
From: "Benny Aumala" <[hidden email]>

> Maybe my interest to QRP is partially because K2.
> I want to use my K3/100 still quite a lot in QRP and QRPP.
> The degree of adjust is really fine down to 0.1W.
> Also, 100W PA switch-off below 10W is very clever.
> But to crank between 100 and 5W is not very handy.
>
> I would like to see PF1 to change powers between two adjustable levels.
>
> Benny    oh9nb
>
>

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[M0XDF]

Well, when you wish to go from 100w, down to 3w, in order to tune an
external tuner (in my case an SGC auto-tuner), it can get tedious.

On 16/1/08 13:48, "Joe-aa4nn" <[hidden email]> sent:

> Benny, it's just the turn of a pot!
> How difficult or inconvenient could that be.  hi
> de Joe, aa4nn
>
> ----- Original Message -----
> From: "Benny Aumala" <[hidden email]>
>> Maybe my interest to QRP is partially because K2.
>> I want to use my K3/100 still quite a lot in QRP and QRPP.
>> The degree of adjust is really fine down to 0.1W.
>> Also, 100W PA switch-off below 10W is very clever.
>> But to crank between 100 and 5W is not very handy.
>>
>> I would like to see PF1 to change powers between two adjustable levels.
>>
>> Benny    oh9nb

--
When work is a pleasure, life is a joy! When work is a duty, life is
slavery. -Maxim Gorky, author (1868-1936)


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[Chris G3SJJ]

Maxim, I'm not sure why you need to go down to 3w. The K3 will sit at
120w for a long time. I don't need to use an ATU here as all my antennas
are fed with coax and remotely swiched, but I do have a manual tune amp.
I have a small printed card fixed with blue tack to the front panel
showing setting per band/mode. A bit like the old ad for Alpha amps,
Tuning By Numbers. 20m CW is 44 /36, so swopping bands is simple. Flick
the band change switch, quickly turn the two dials to those settings,
apply RF and do final fine tune. All done within a few seconds. The only
thing I have to watch is knock the power knob back on the MP to roughly
the area I know that gives me a reasonable ampount of power out of the
amp, say 30-50 watts. I would have thought this technique would have
been OK with the K3.

Chris G3SJJ

> Well, when you wish to go from 100w, down to 3w, in order to tune an
> external tuner (in my case an SGC auto-tuner), it can get tedious.
>
> On 16/1/08 13:48, "Joe-aa4nn" <[hidden email]> sent:
>
>  
>> Benny, it's just the turn of a pot!
>> How difficult or inconvenient could that be.  hi
>> de Joe, aa4nn
>>
>> ----- Original Message -----
>> From: "Benny Aumala" <[hidden email]>
>>    
>>> Maybe my interest to QRP is partially because K2.
>>> I want to use my K3/100 still quite a lot in QRP and QRPP.
>>> The degree of adjust is really fine down to 0.1W.
>>> Also, 100W PA switch-off below 10W is very clever.
>>> But to crank between 100 and 5W is not very handy.
>>>
>>> I would like to see PF1 to change powers between two adjustable levels.
>>>
>>> Benny    oh9nb
>>>      

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[M0XDF]

Firstly, it's David, at least it was when I replied :)

I go down to 3w for two reasons:
1) so I'm not tuning up over a SSB signal with 120W of carrier
2) so I don't strain the K3 components that back off with high SWR

3w appears to be min the SC-237 will tune on reliably. I can get it to tune
on 2w sometimes, but that depends upon band.


On 16/1/08 14:33, "G3SJJ" <[hidden email]> sent:

> Maxim, I'm not sure why you need to go down to 3w. The K3 will sit at
> 120w for a long time. I don't need to use an ATU here as all my antennas
> are fed with coax and remotely swiched, but I do have a manual tune amp.
> I have a small printed card fixed with blue tack to the front panel
> showing setting per band/mode. A bit like the old ad for Alpha amps,
> Tuning By Numbers. 20m CW is 44 /36, so swopping bands is simple. Flick
> the band change switch, quickly turn the two dials to those settings,
> apply RF and do final fine tune. All done within a few seconds. The only
> thing I have to watch is knock the power knob back on the MP to roughly
> the area I know that gives me a reasonable ampount of power out of the
> amp, say 30-50 watts. I would have thought this technique would have
> been OK with the K3.
>
> Chris G3SJJ
>
>> Well, when you wish to go from 100w, down to 3w, in order to tune an
>> external tuner (in my case an SGC auto-tuner), it can get tedious.
>>
>> On 16/1/08 13:48, "Joe-aa4nn" <[hidden email]> sent:
>>
>>  
>>> Benny, it's just the turn of a pot!
>>> How difficult or inconvenient could that be.  hi
>>> de Joe, aa4nn
>>>
>>> ----- Original Message -----
>>> From: "Benny Aumala" <[hidden email]>
>>>    
>>>> Maybe my interest to QRP is partially because K2.
>>>> I want to use my K3/100 still quite a lot in QRP and QRPP.
>>>> The degree of adjust is really fine down to 0.1W.
>>>> Also, 100W PA switch-off below 10W is very clever.
>>>> But to crank between 100 and 5W is not very handy.
>>>>
>>>> I would like to see PF1 to change powers between two adjustable levels.
>>>>
>>>> Benny    oh9nb

--
Any sufficiently advanced technology is indistinguishable from magic.
-Arthur C Clarke, science fiction writer (1917- )


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[Julian, G4ILO]

M0XDF wrote

Well, when you wish to go from 100w, down to 3w, in order to tune an
external tuner (in my case an SGC auto-tuner), it can get tedious.

I can imagine. It's bad enough from 10W. The K2 power control didn't have this problem. A twist of the wrist was all that was needed.

[Julian, G4ILO]

M0XDF wrote

I go down to 3w for two reasons:
1) so I'm not tuning up over a SSB signal with 120W of carrier
2) so I don't strain the K3 components that back off with high SWR

3w appears to be min the SC-237 will tune on reliably. I can get it to tune
on 2w sometimes, but that depends upon band.

I do the same when tuning my MFJ magnetic loop, except I do it at 1W.

One thing I miss. On the K2, ATU bypass was CAL S, so I got a digital SWR reading when I was tuning. That was handy because it is much easier to detect the perfect match using a digital readout than trying to detect the null in the reflected power meter of the tuner. In ATU BYPASS mode the K3 doesn't display the SWR, though presumably it's still measuring it so the PA can protect itself from extreme mismatches in bypass mode.

[M0XDF]

It does display the SWR on VFOA display when you hold TUNE, but only at 2W+.

On 16/1/08 16:57, "G4ILO" <[hidden email]> sent:

> One thing I miss. On the K2, ATU bypass was CAL S, so I got a digital SWR
> reading when I was tuning. That was handy because it is much easier to
> detect the perfect match using a digital readout than trying to detect the
> null in the reflected power meter of the tuner. In ATU BYPASS mode the K3
> doesn't display the SWR, though presumably it's still measuring it so the PA
> can protect itself from extreme mismatches in bypass mode.

--
When work is a pleasure, life is a joy! When work is a duty, life is
slavery. -Maxim Gorky, author (1868-1936)


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[David Pratt-2]

In a recent message, G4ILO <[hidden email]> wrote ...
>In ATU BYPASS mode the K3
>doesn't display the SWR, though presumably it's still measuring it so the PA
>can protect itself from extreme mismatches in bypass mode.

Mine does, Julian.  Put ATU in Bypass, then hold XMIT/TUNE and the SWR
is displayed.

73
--
David G4DMP
Leeds, England, UK
------


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[Julian, G4ILO]

M0XDF wrote

It does display the SWR on VFOA display when you hold TUNE, but only at 2W+.

So it does. Guess I'll just have to tune at a higher power level.