http://elecraft.85.s1.nabble.com/K3-Manual-change-suggestion-tp2479552p2491191.html
between. The K2 power controls may not have time to react with the
Stephen W. Kercel wrote:
> Don:
>
> I'm glad to hear from you on this. I talked to Scott at Elecraft earlier
> in the day, and he said that he had never heard of anyone using a tuning
> pulser with a K2, but that if anyone would understand the possible
> quirks it would be you.
>
> In addition to the "one bar less than normal keying," I have discovered
> another quirk. If I change bands, and then try to run the pulser, the
> transmitter does not key. I hear the side tone, but the K2 power meter
> shows no bars. Also, the peak reading Watt meter in series with my dummy
> load shows no RF output. I can remedy the problem by reverting to the
> regular keyer and tweaking the power level between QRP and QRO levels.
> Somehow this seems to reset something in the rig. Once it transmits at
> regular keying speeds, if I subsequently go to the tuning pulser, then
> the K2 will transmit the pulses.
>
> I have not yet looked at the RF output on a scope. What I have noticed
> is that once the transmitter does turn on, the peak reading Watt meter
> in series with the dummy load gives me about the same peak reading both
> for the pulser and normal keying.
>
> These various quirks do suggest to me that the the 12 ms "on" interval
> is too short for the K2 to respond properly. Thus, your suggestion of
> doubling the "on" interval sounds like a good possibility for
> sidestepping these quirky behaviors. Both the "on" and "off" durations
> are determined by a 0.1 uF capacitor in the timing circuit of the
> pulser. If I change the capacitor to 0.18 uF (values of 0.2 uF seem hard
> co come by), it would change the "on" interval to 22 ms and preserve the
> 33% duty cycle.
>
> Unfortunately, the local Radio Shack does not carry these values, and
> I'll need to order a new capacitor from Mouser. Thus, it will be a few
> days before I can give this modification a try.
>
> I'll let you know how it turns out.
>
> BTW, for those who are curious, the Web page describing the pulser is
>
>
http://www.somis.org/D-a-09.GIF>
> The version that I built is the one transistor version.
>
> TXN & 73,
>
> Steve Kercel
> AA4AK
>
>
> Don Wilhelm wrote:
>
>> Steve,
>>
>> I have not yet seen an answer on the reflector, so I will offer some
>> comments. First, I do not think your pulser will hurt the K2 in any way.
>> Secondly, I am at a loss to know why you do not see as many bars in
>> the K2 LED display as you do in TUNE. The bargraph is relatively fast
>> responding and should indicate the power level being transmitted. It
>> may be that your pulser ON duration is too short and it causes a
>> 'flicker' in the display that is not seen by the eye.
>> It would be interesting to see what an oscilloscope connected across
>> the K2 output would reveal (the oscilloscope display would react in
>> even less time than the bargraph).
>>
>> So, bottom line, you may be seeing a natural result of the pulser ON
>> time rather than an actual fault of the K2. Is there an easy way to
>> double the ON time for your pulser? I find it hard to believe that 24
>> ms of ON time would cause any problems for your amplifier - it
>> certainly would not pose any problems for the K2.
>>
>> 73,
>> Don W3FPR
>>
>>
>> Stephen W. Kercel wrote:
>>
>>> Elecrafters:
>>>
>>> I built a tuning pulser to use with my K2/100 to tune an external
>>> linear amplifier. The pulser is the AG6K design. The pulse is 12 ms
>>> on and 24 ms off, and repeats about 28 times per second. This is (by
>>> design) much faster than the normal 25 wpm or so keying out of the
>>> keyer.
>>>
>>> The interface between the pulser and the K2 is a 2N2222 NPN
>>> transistor used as a switch. The key line to the K2 is connected to
>>> the collector of the transistor (nothing else is connected to the
>>> collector), the switching data comes in through the base, and the
>>> emitter is grounded both to the ground side of the pulser circuit and
>>> the ground side of the keying line back to the K2.
>>>
>>> I notice what seems to me to be an odd phenomenon when I key the K2
>>> with the pulser. When I first switch on the pulser, the power level
>>> in the little LED power meter on the K2 shows the same power level as
>>> I get in normal keying. However, after the first instant, the power
>>> level indication drops one bar lower (and then stays there as long as
>>> the pulser is on) than the power level indication under normal
>>> keying. This effect occurs independent of the power level that I set.
>>> It happens with the K2's 100 Watt amplifier both in and out.
>>>
>>> Is this simply an artifact of the metering circuit caused by the
>>> peculiar duty cycle of the pulser?
>>>
>>> Most critically, will it harm the K2?
>>>
>>> Should I do as one alternative keying scheme shows, and use the
>>> transistor to key a reed relay and use the reed relay (which would
>>> simply hard short the K2 keying line on key down) to key the K2?
>>>
>>> TNX & 73,
>>>
>>> Steve Kercel
>>> AA4AK
>>>
>>>
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>
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