[karc] Re: Soften Rockmite Side tone
- From: Valveman <valveman_6146@xxxxxxxxx>
- To: karc@xxxxxxxxxxxxx
- Date: Tue, 22 Jun 2010 18:26:55 -0700 (PDT)
For the power jack, you can use a piece of heat shrink to prevent shorting.
Yes I noticed the thump. This is due to the switching from RX to TX. This can
also be reduced significantly by adding a RC circuit with quick response to
temporarily send the audio to ground for a fraction of a second during
switchover. I will look at the thump on my digital storage scope and see if I
can come up with a solution. Then the mods will work much better with no thump.
Thanks for bringing this up Phil.
More to follow
Robert Parker
VE3RPF
________________________________
From: Phil Somers <pwsomers@xxxxxxxx>
To: karc@xxxxxxxxxxxxx
Sent: Tue, June 22, 2010 8:36:06 PM
Subject: [karc] Re: Soften Rockmite Side tone
> Here is a link I found for a mod to soften the side tone.
> http://www.qsl.net/wb6dwd/RockMiteSidetone.htm
> Robert Parker
> VE3RPF
I tried that modification and I tried Rob's earlier modification. Both lowered
the volume of the sidetone. I'm not sure the one in the link improved the tone.
I also tried a smaller capacitor for C8 and that also lowered the volume.
However, lowering the sidetone volume introduced a new problem. The
transmit/receive switching (break-in) works very smoothly but it has a "thump"
sound that becomes obvious when the sidetone is lowered. I tried keying with no
sidetone at all and the T/R thump is quite significant. When the sidetone is
quite loud, it masks the thump.
So I have gone back to the original circit. The sidetone is a bit loud but not
objectionable. But I find the thump objectionable. Maybe my sidetone and T/R
circuits are working a bit differently than Rob's or others.
One other lesson-learned. The power supply plug that came with the Rockmite kit
has a "got-cha". Notice that the centre conductor part of the plug extends a
slight bit past the front of the plug. Once when I was plugging it in, I
touched against the side of the jack in such a way that it shorted. Fortunately
I has a fuse in the power supply leads. Another reason to install a power
on/off switch so you don't have to use the plug/jack as an on/off switch.
... Phil VE3HST
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