[Elecraft] Re: 6M Preamp

[wayne burdick]

G4AON asked about the K3's price class vs. 6 m sensitivity.

The K3 was designed from the ground up to exceed the dynamic range of 
every ham transceiver available. That it does (see Sherwood, the QST 
review, or our own K3 page).

In order to achieve this, we had to use a down-conversion design to a 
low I.F. This requires narrow band-pass filters on each ham band, plus 
supplemental image-rejection filtering on the highest bands. Other rigs 
make different tradeoffs -- usually sacrificing dynamic range.

The narrow BPFs result in a loss ahead of the existing preamp and 
switching mixer that is nearly ideal for the HF bands, in terms of 
maximizing dynamic range in challenging operating situations. That was 
our primary goal. (We were also trying to keep the basic transceiver 
affordable, and achieve a form-factor consistent with DXpeditions and 
portable operation in general. There are many more things we wanted to 
add that were outside budgetary constraints, but we adding the needed 
"hooks" in the I/O.)

For some applications on 6 m you might want a lower NF, and we took 
this into account by providing a path into which you could patch an 
external preamp, if necessary. Thus the RX IN and RX OUT jacks on the 
KXV3. We also provided a way to power it (12VDC OUT) and turn it off/on 
(DIGOUT1). We also included through-mode jacks on the PR6 itself so it 
can be bypassed while still allowing the connection of RX antennas or 
filters for other bands.

The resulting MDS with the PR6 inserted is better than nearly every HF 
transceiver that also covers 6 m. Of course many 6-m stations doing 
weak-signal work already have external preamps either in the shack or 
mounted at the antenna, and they likely will not need the PR6.

73,
Wayne
N6KR
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