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Mini-Circuits ADT1-6T
The next 1:1 transformer tested is the ADT1-6T. The following table lists the results:
| FSA3157 + ADT1-6T + 74AC04 |
Vdd = 7.0V, Vbias = 2.5V |
Best bias |
| Band |
BPF |
mixer |
MDS -dBm |
IF rej |
spur |
mixer IIP3 (dBm) @ 20KHz spacing |
Bias |
IIP3 |
| IL |
CL |
- |
+ |
|
avg |
-6 |
-3 |
0 |
+3 |
+5 |
|
0 |
| -dB |
-dB |
BPF |
BPF |
-dB |
dB |
dBm |
dBm |
dBm |
dBm |
dBm |
V |
dBm |
| 160 |
3,3 |
4,80 |
133,5 |
130,0 |
49,6 |
|
|
|
44,2 |
|
|
2,5 |
44,2 |
| 80 |
1,4 |
4,80 |
133,5 |
132,0 |
50,8 |
|
46,5 |
48,7 |
50,2 |
49,2 |
48,7 |
2,5 |
50,2 |
| 40 |
2,3 |
4,84 |
133,5 |
131,0 |
52,0 |
|
|
|
50,2 |
|
|
2,5 |
50,2 |
| 30 |
3,4 |
4,88 |
133,5 |
130,0 |
51,6 |
|
|
|
47,5 |
|
|
2,5 |
47,5 |
| 20 |
3,4 |
4,92 |
133,5 |
130,0 |
53,2 |
|
|
|
45,4 |
|
|
2,5 |
45,4 |
| 17 |
3,0 |
5,00 |
133,5 |
129,5 |
63,6 |
|
|
|
46,1 |
|
|
2,5 |
46,1 |
| 15 |
3,9 |
5,12 |
133,5 |
129,0 |
54,0 |
4,7 |
|
|
42,9 |
|
|
2,5 |
42,9 |
| 12 |
3,7 |
5,24 |
133,0 |
128,5 |
42,8 |
|
|
|
41,8 |
|
|
2,5 |
41,8 |
| 10 |
2,3 |
5,36 |
133,0 |
130,5 |
38,4 |
|
|
|
42,0 |
|
|
2,5 |
42,0 |
| 6 |
|
5,52 |
132,0 |
|
47,2 |
|
|
|
42,0 |
|
|
2,5 |
42,0 |
| 4 |
|
5,88 |
131,5 |
|
26,0 |
|
|
|
36,9 |
|
|
3,0 |
37,4 |
Conversion loss is good, below -5,36dB on HF but steadily worsening on higher frequencies, much like ADTT1-6.
Average spur level with the ADT1-6T is poor at 4,7dB. Note that this applies to a mixer adjusted for best RF-IF isolation, so nothing special was done to minimize the spur level. When adjusted to minimize the spur levels it can be reduced to -6,9dB average although at the expense of much reduced RF-IF isolation (-28dB).
With regard to the spur rejection the ADT1-6T is not quite as good as the ADTT1-1. This can be predicted from the spec-sheets too. Phase and amplitude balance are not so good at VHF causing bad symmetry for the spurs when adjusted for best symmetry at the operating frequency.
RF-IF isolation is excellent, better than -50dB, if band specific adjustments are made. The levels in the table are for the best isolation on 15M.
The ADT1-6T combination has the best average bias point at 2.5V. On 4M however the IP3 can be slightly improved with a 3V bias point. No steep dips on any band though. This configuration is almost bias point independent.
This mixer configuration behaves very well with regard to IP3's 3rd order law. The IP3 is very flat over a wide input range on 80M, slightly peaking at 0dBm input level!
The ADT1-6T mixer combination is the first to exhibit >+40dBm IP3 on all HF bands including 6M.
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