K2 General Coverage RX Use

There has been some discussion of the potental use of the K2 out-of-band to serve as a SWL radio as well. During the assembly of my K2, I chose to map the VCO ranges from the lower PLL lock limit to the upper lock limit. While I was doing this I checked the receive sensitivity as well.

The adjustment of L30 in the VCO Calibration sets the lock range of the VCO for every band. The Elecraft choice of 6.0v as the adjustment point allows the VCO ranges to overlap judiciously to cover other frequencies.

The results of my measurements are shown in the first table below. Note that in some cases a valid lock is obtainable while the receiver is not useable because of noise introduced by the PLL near the lock limit. So the first row of a given band is the measured lock limits, while the second row is the usable bandwidth for my K2. The columns are the band selected on the K2 , the frequency when the VCO tune voltage is 1.1v, the minimum discernable signal (MDS), the frequency when the VCO voltage is 7.9v, and the MDS.

Band

Freq (1.1v)

MDS (dBm)

Freq (7.9v)

MDS (dBm)

80m

2460

 

4167

 

 

3380

-125

4150

-112

 

 

 

 

 

40m

6658

 

7490

 

 

6660

-121

7450

-118

 

 

 

 

 

30m

9146

 

10749

 

 

9150

-118

10750

-114

 

 

 

 

 

20m

12458

 

15771

 

 

12750

-100

15750

-112

 

 

 

 

 

18m

15434

 

20501

 

 

(oops)

 

 

 

 

 

 

 

 

15m

20246

 

22378

 

 

20300

-110

22350

-112

 

 

 

 

 

12m

22237

 

25600

 

 

22300

-104

25600

-112

 

 

 

 

 

10m

25353

 

30315

 

 

25500

-110

30300

-102

NOTE: -107 dBm = 1uv into 50ohms, Freq is in kHz, meas w/ IFR1500

Note these are all 'casual' MDS numbers in dBm, casual in that I guessed at about 6-10dB SNR audio but did not get out the scope or the FFT.  Preamp is on.  My curiosity was SWL on the trail, not contesting here *8-)  numbers should be very conservative.

The next table maps my K2ís band coverage against the standard SWL bands. Of note is that all but 3 SWL bands are covered (60m, 4.7-5.1mhz; 49m, 5.9-6.2; 25m, 11.6-12.1) which is plenty good for me. 

 The Receive performance data was also impressive to me.  For my purposes of casual SWL the K2 is very usable out of band - even though it looses as much as 20dB rx performance in many cases...

 SW Band

Freq

K2 VCO

K2 Band

Notes

120m

2250 - 2550

***

160m

 

90m

3150 - 3450

3380 - 4150

80m

 

75m

3850 - 4050

3380 - 4150

80m

 

60m

4700 - 5100

 

 

 

49m

5900 - 6250

 

 

 

41m

7100 - 7400

6660 - 7450

40m

 

31m

9400 - 10000

9150 - 10750

30m

 

25m

11500 - 12150

 

30m

 

22m

13500 - 13900

12750 - 15750

20m

 

19m

15000 - 15700

12750 - 15750

20m

**

16m

17450 - 18000

(oops)

18m

**

13m

21450 - 21950

20300 - 22350

15m (12m)

**

11m

25600 - 26100

25500 - 30300

10m

**

NOTE: ** indicated bands overlap

72,

Niel Skousen    WA7SSA