ELECRAFT KPA3 Specifiche Scaricare il pdf (Pagina 8)

From January 2009 QST © ARRL

diversity reception, it’s best to use filters with identical width

and specs in each receiver to avoid phasing problems.

To test diversity reception, I used a Y cable to connect my

580 foot northeast Beverage low noise receive antenna to the

K3’s RX ANT jack and the subreceiver’s AUX RF jack so I could

use the Beverage as either a receive-only antenna or a di-

versity antenna. I also modified my antenna switching system

so I could feed a number of different transmit antennas to the

subreceiver.

Diversity reception takes some getting used to. Because

of the stereo effect and variation of signal strength on each

of the antennas, signals sometimes seem to “float” around

between your ears. But the ability to dig out weak signals

is impressive at times, and well-worth the slightly strange

audio. I found the combination of my two element 40 meter

Yagi and 40 meter four square vertical array to be particularly

effective. Here the difference in polarization and arrival angle

often overcame the effects of selective fading. I was able to

copy better through static crashes, too. Since my two element

beam has a 20 dB front-to-back ratio, I was able to periodi-

cally listen “off the back” of the beam by pointing the four

square to that direction. I had similar results when using the

Beverage and inverted V antennas on 160 and 80 meters. It

was often easier to copy weak signals, and nice to be able to

hear Caribbean stations on the inverted-V while still hearing

European stations loud and clear on the Beverage.

LP-PAN and CW Skimmer

When putting in a full-time, serious contesting effort, I

always compete in the Single Operator category. A one-time

ruling allowed CW Skimmer software to be used in the Single

Operator category in the 2008 IARU contest, so I had an

opportunity to evaluate the K3 as an IF receiver for the

LP-PAN panadapter.

My setup also used PowerSDR-IF

software and LP-Bridge software to link PowerSDR to the

K3. For full details of this powerful K3 accessory, see

www.telepostinc.com.

Setting up CW Skimmer can be challenging, a subject

that’s beyond the scope of this sidebar. Suffice it to say that

the best approach is to use CW Skimmer with a dedicated

wide-band receiver and a dedicated antenna. Not having

those items at my disposal, the K3 had to do double duty

as both a CW Skimmer receiver and an S&P transceiver.

Technical limitations in CW Skimmer didn’t allow me to do

these things at the same time. So, I had to let CW Skimmer

run for a few minutes to decode signals in the passband

and load up the contest logger’s bandmap with call signs

and frequencies. Then I shut it off so I could grab and work

the stations spotted on the bandmap. Although somewhat

cumbersome, this technique netted enough second radio

multipliers and contacts for me to place well in the contest.

Bottom line: The K3 performed admirably as an S&P and

CW Skimmer radio.

The K3’s small size can be deceiving. Inside the diminu-

tive package is a world-class, state-of-the-art contest radio

with a pair of the best receivers I’ve used. — Dick Green,

WC1M

CW Skimmer (www.dxatlas.com) simultaneously decodes all CW

signals within the receiver passband, and its use has been the subject

of much discussion within the contest community. The latest rules for

most major contests indicate that it can be used only in those cate-

gories that allow use of spotting networks and other assistance.

quickly replaced by Elecraft and operation

was back to normal.

Firmware and Support

I have grouped these together, because

with Elecraft they go hand in hand. With an

SDR radio such as the K3, each firmware

reload can provide almost a whole new radio,

within the constraints of the front panel con-

trols and displays. Thus, most support issues

of an architecture or design implementation

nature are resolvable in firmware.

Elecraft has been, in my opinion, remark-

ably responsive in this area. The company

principals regularly participate in, and even

moderate, the e-mail discussion list (see

mailman.qth.net/mailman/listinfo/ele-

craft). Reported bugs are usually resolved

within a day or two by the posting of new

firmware. Feature changes or different

operating options are discussed by a lively

group with participation from the principal

developers. If a consensus emerges, the next

beta version will include the feature. If there

is no clear consensus, the feature may end up

a menu option.

A recent example was the use of the

A>B button. Originally a touch of the button

would cause the frequency, mode, bandwidth

and other settings to be transferred between

VFO A and VFO B. It was changed in a sub-

sequent release to transfer just the frequency

to VFO B on the first tap, then transfer the

other parameters on the second. This seems

a bit esoteric, but the respectful discussion

raised good reasons for both approaches un-

der different scenarios. The review, including

all testing, was conducted using firmware

version 2.46, the current production code

during the review process.

Documentation

Elecraft has done an excellent job with K3

documentation. Check it out yourself — it’s

all available on their Web site, including as-

sembly manuals for the base K3 and all the

options as well as the operating manual. The

one problem is that a manual is frozen in time

with only the changes that have happened up

until publication.

There are a number of ways to handle a

dynamic environment such as the K3 with

its frequent firmware releases. Elecraft has

chosen to issue release notes with each soft-

ware revision that describe all the operational

changes that have been incorporated. I have

a loose leaf binder with the latest manual

and all the release notes issued since the

manual revision. This is a viable way to

do it, but I’d prefer manual change pages

with each release so the manual index and

table of contents would get you to the latest

information. Of course there are those who

get their K3 and are thrilled with what it

does and how it does it and never upgrade

their software — that’s another viable option.

After all, there was a time when all radios

worked that way!

More to Come

Two additional options for the K3 have

been announced, but were not available in

time for this review. The KDVR3 voice re-

corder provides over 6 minutes of nonvolatile

voice storage. This is divided between eight

one button user recorded message buffers, re-

cording signals off-the-air for later playback

or even for use as keypress annunciators. The

one-button buffers can be used for calling

CQ or contest exchanges or even to record

received audio.

The K3 receiver was designed with opti-

mized dynamic range as its primary goal. As

noted, it has achieved that nicely — thank

you very much. Unfortunately, it is difficult to

obtain highest sensitivity and highest dynam-

ic range in the same radio. The sensitivity is

fine for HF, where external noise is generally

the limiting factor, but for some K3 owners

additional sensitivity is needed on 6 meters.

The optional PR6 GaAs FET low noise

6 meter preamp can be connected to the

KXV3 interface panel so that the transverter

connections feed through when it’s not in

use. It promises a typical noise figure of

0.5 dB.

Manufacturer: Elecraft, PO Box 69,

Aptos, CA 95001; tel 831-662-8345;

www.elecraft.com.

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