[hpsdr] Resistor value to be changed: R141 of Hermes

[Tokio Endo]

Hi All,

I use Hermes by using External 10MHz clock.
Recently I noticed receiving CW tonality abruptly changed in a very very
short period. It's very subtle.

Then I hooked a probe of an oscilloscoe on JP20 to see the shapes of the
clock, when External or Internal.
The differecne between the both is quite apparent, the output level of two
transistor's wave shapping circuit for External clock is low.

By sharing this phenomenon with Phil, VK6APH, I changed the value of R141
from original 100 ohms to 51 ohms.
The result is OK, the level is almost same as External clock's one.

According to the schematics of Hermes as well as BOM, R141 is 100 ohms, but
in my case it doesn't work properly.

If you use External clock, check the value of R141 and see the clock shape
of JP20 at JP20 if an oscilloscope is available.

If there is a difference compared with Internal clock shape, I recommend you
to change the value of R141 to 51 ohms.

73,
Tokio Endo
JA1CCA

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/attachments/20130224/9e631533/attachment-0003.htm>