[Elecraft] Loudspeaker click reduction and more audio power

[j.j.leijssen@philips.com]

> Jack Leijssen PA1W wrote: 
>
> > The only small remark I have is:
>> > Switching of the powerswitch gives a sharp noisy click in the 
>> > headphone (and speaker). Such a high quality radio may not do this. 
>> 
>> Sverre Holm, LA3ZA replied:
>>
>> Seriously, hi-fi equipment often uses a relay to delay the 
>> connection of the loudspeakers on turn-on and to disconnect 
>> them instantly as power is turned off. This would be the 
>> ultimate solution.
>>

>Both of them use a topology called BTL = Bridge Tied Load which means
>that there are essentially two amplifiers operating out of .........


Sverre,

thanks for responding to my request to find a solution for the 
loudspeaker/headphone click problem.
It is just a minor problem, till now the only thing I could find on the 
K2. The K2 is still a great radio. Last weekend I worked my first DX from 
Europe, with KE4RUN, output 5W and battery powered, also my first QSO on 
10mtrs.

Your suggestions let me think about placing an extra LM380 on top of the 
other one. Both of them are placed in a bridge then. Regarding the LM380 
datasheet this is possible. The advantage can be that I do not have to 
remove something, just glue it on top of the other. And change the 
loudspeaker's wiring. Probably this will reduce the switching click as 
well. 
This  will also increase the audio output power. I think double the 
voltage over the speaker so 4 times the audio power. Some precautions must 
be taken not to overheat the LM380s, or destroy the speaker. Maybe a piece 
of aluminium for cooling and a serial resistor.

Regards,

Jack Leijssen
PA1W
K2 #3818

--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
The reason this message is shown is because the post was in HTML
or had an attachment.  Attachments are not allowed.  To learn how
to post in Plain-Text go to: http://www.expita.com/nomime.html  ---