I suppose the "click" - or in my case a "thump" - depends on the timing
of the "mute" signal from the controller and the value of the bypass
capacitor on pin 8 of the speaker amplifier. The chip manufacturer
recommends 10 uF for the bypass capacitor but I notice that Elecraft
use 3.3 uF in the K3. The manufacturer's data sheet shows:
Cb (uF) Ton (Ms)
1.0 120
2.2 120
4.7 200
10.0 440
The manufacturer's data sheet also calls for the time constant of the
input coupling capacitor and Ri+Rf (input and feedback resistors of
the amplifier) to be less than the turn on time set by Cb. In the
K3, I don't know how critical the ratio of input time constant to
turn on time is but the reference design has an input time constant
less that 5% of the turn on time while in the K3 the input time
constant is about 30% of the turn on time.
In addition, I suspect there may be some variation in early vs. late
production due to the change in the DC resistance of the RF choke in
the DC line feeding the speaker amplifier.
73,
... Joe, W4TV
On 9/4/2011 5:01 PM, John Ragle wrote:
> I run K3/100 Ser. No. 4103. It has a relay click on power on, but
> nothing from the speakers. Go figure...
>
> John Ragle -- W1ZI
>
> =====
>
> On 9/4/2011 4:46 PM, Mike wrote:
>> The external speakers have a pretty loud pop at power on. The headphones do
>> not. K3 3539.
>>
>> 73, Mike NF4L
>>
>> On 9/4/2011 2:13 PM, Stephen Prior wrote:
>>> I think that this has been mentioned before, but the K3 has a pronounced
>>> turn on click through the loudspeaker. When connected to external speakers,
>>> the click is loud and out of character with the quality feel of the radio.
>>> It would be a good idea in my opinion if the audio output were to be
>>> muted
>>> for a fraction of a second after the K3 is turned on.
>>>
>>> 73, Stephen G4SJP
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft@mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
