Sverre.
I beg to differ slightly. The B level boards already have the 82mH
inductor across the same R-PAK that the TF3MA mod wants to install the
large capacitor. In addition, the 47k resistor is already in place, but
the path must be broken to install his 47mH inductor.
While it is do-able on the B level board, it is not as straightforward
as for the A level board. To follow the TF3MA instructions as written,
one must have the A level board. With the B level, the existing design
must be modified and the mod re-designed a bit.
For circuit savvy K2 owners who understand how to follow a schematic, it
should not be a problem, but those lacking that ability should proceed
with caution and the help of someone who can interpret the schematic.
73,
Don W3FPR
On 3/23/2016 5:30 PM, Sverre Holm (LA3ZA) wrote:
The TF3MA sidetone mod is still current as it is in fact a modification of
the B level board, not just the A level board, as the site states that this
is an improvement of exactly the 47k / 82 mH A to B improvement mentioned in
the quote below. See
http://www.raunvis.hi.is/~matti/TF3MA/sidetone_tf3ma.html
See also my mod list here:
http://la3za.blogspot.no/p/la3za-unofficial-guide-to-elecraft-k2_28.html
(search for sidetone), where I specify it as : "Even more sinusoidal tone
than the mod in serial #3000+ gives"
Don Wilhelm-4 wrote
Yes, those two mods are old, and apply only to the A level boards (below
SN 3000).
There have been improvements in the K2 sidetone incorporated into the B
level boards, and are also included with the A to B mod kit.
The changes added a 47k resistor in series with C24 (R11 for the B level
boards) and a shielded 82mH inductor across pins 7 and 10 of RP5.
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