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Mini-Circuits T1-6T
The next 1:1 transformer tested is the T1-6T. The following table lists the results:
| FSA3157 + T1-6T + 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 |
4,72 |
133,5 |
130,0 |
52,8 |
|
|
|
46,2 |
|
|
2,5 |
46,2 |
| 80 |
1,4 |
4,80 |
133,5 |
132,0 |
54,4 |
|
46,7 |
48,7 |
50,2 |
50,2 |
50,0 |
2,5 |
50,2 |
| 40 |
2,3 |
4,76 |
133,5 |
131,0 |
55,2 |
|
|
|
50,9 |
|
|
2,5 |
50,9 |
| 30 |
3,4 |
4,80 |
133,5 |
130,0 |
55,2 |
|
|
|
49,3 |
|
|
2,5 |
49,3 |
| 20 |
3,4 |
4,80 |
133,5 |
129,5 |
65,6 |
|
|
|
47,2 |
|
|
2,5 |
47,2 |
| 17 |
3,0 |
4,88 |
133,5 |
129,0 |
56,6 |
|
|
|
45,1 |
|
|
2,5 |
45,1 |
| 15 |
3,9 |
5,00 |
133,5 |
129,0 |
63,2 |
2,3 |
|
|
44,9 |
|
|
2,5 |
44,9 |
| 12 |
3,7 |
5,00 |
133,5 |
128,5 |
45,6 |
|
|
|
42,1 |
|
|
2,5 |
42,1 |
| 10 |
2,3 |
5,04 |
133,5 |
130,5 |
40,4 |
|
|
|
42,8 |
|
|
2,5 |
42,8 |
| 6 |
|
5,20 |
132,5 |
|
47,6 |
|
|
|
40,5 |
|
|
2,5 |
40,5 |
| 4 |
|
5,48 |
129,5 |
|
26,0 |
|
|
|
39,6 |
|
|
2,5 |
39,6 |
Conversion loss is excellent, below -5,04dB on HF but steadily worsening on higher frequencies, much like ADTT1-6.
Average spur level with the T1-6T is rather poor at 2,3dB. 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 -1,2dB average although at the expense of much reduced RF-IF isolation (-28dB).
RF-IF isolation is excellent, better than -60dB, if band specific adjustments are made. The levels in the table are for the best isolation on 15M.
The T1-6T combination has the best average bias point at 2.5V. No steep dips on any band though. This configuration is almost completely bias point independent.
This mixer configuration behaves very well with regard to IP3's 3rd order law. The IP3 is completely flat over a wide input range on 80M!
The T1-6T mixer combination is the third to exhibit >+40dBm IP3 on all HF bands including 6M and almost 4M!
Except for its VHF symmetry (spurs...) the T1-6T is the best mixer in this compilation. It combines the best conversion loss with very good RF-IF isolation and very good IP3 on all bands especially 80 and 40 with superb 3rd order linearity.
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