[Elecraft] Re: 817 audio better than K2?

[Wayne Burdick]

Tim and Nancy Logan wrote:

> Is the 817's audio
> amplification just plain stronger or is this an indication that my K2's
> audio needs tweaking (and how would I do it?).


Hi Tim,

It could be a little of both.

The FT817, like almost all-band SSB/CW transceiver *but* the K2, is
multiple-conversion. Because of the added gain at each stage, its
overall receive gain is probably several dB greater than the K2's.
However, the FT817's receiver has much worse dynamic range. These are
tradeoffs that most manufacturers are willing to accept, because hams
are used to receivers with lots of gain (that are "in the AGC" at all
times, even on fairly weak band noise). On top of that, the FT817 is
intended for use with short, inefficient antennas. The K2's lower total
gain is the reason for its suitability for use as a transverter I.F.,
and for its characterization by ops as "quiet".

That said, there are several things that you might want to check. 

The value of R1 on the Control board sets the resting AGC threshold for
the MC1350, and you may want to make it smaller. (In fact if we ever
change the K2 design, we'll probably make this a pot.) You could have
AGC activation coming on at too low a signal level.

Also check filter and BFO alignment.

Finally, a number of K2 builders have reduced the size of the emitter
resistor in the preamp from 10 ohms to 5.6 or 6.2 ohms, bringing up
signal levels significantly when the preamp is in use. This could be
especially important if you want to use short antennas with your K2.

Gary Surrency can give you a longer list of suggestions if you need them.

73,
Wayne
N6KR