HighBand RF Board

[Titanus]

Hi,
Today i built the high Band Board. Building was fine, no problems at all. The first test was a little bit a frust for me, because I am very far away from good effeciency and power. I know, I must tune it (waiting for my nano vna, comming soon) but the untuned values are very far away:
10m 3 Watts.......31% eff
20m 4,37 Watts...64% eff
17m 3,85 Watts...63% eff
15m 3,5 Watts....35% eff
12m 4,8 Watts....61% eff

All at 12,5 Volt
Have others the same experience? what values have you after a fresh built untuned high band board?

Lo Band board works fine without any issues.

[epfly.yctseng]

I have the same problem like you. For 10m band, I use 7 turns instead of 5 turns and then the efficiency back to around 69%. For 15m band, L31 change from 7 turns to 8 turns. Of course, R Shunt should have some value fine tune using external power meter to match the (tr)uSDX display value.

[Titanus]

After adjusting a little bit the 10m coils I have now 4,8Watts and 63%eff on 10m. I am thinking of winding the T2 transformer with new 0,3mm wire instead of the original 0,40. Little bit more space between each wind could be good.
It would be very interesting, which values others have on the high bands.

greatings

Alex

[Luca66]

viewtopic.php?t=765

After tuning with Nanovna


20m
V=12,2 V
Irx 84 mA
Itx 530 mA
Pout 3.76 W
Pin 5,44 W
E 69 %

17m
V=12,18 V
Irx 85.7 mA
Itx 620 mA
Pout 4.45 W
Pin 6.5 W
E 68,46 %

15m
V=12,16 V
Irx 87 mA
Itx 810 mA
Pout 5.29 W
Pin 8.8 W
E 60 %

12m
V=12,15 V
Irx 88.5 mA
Itx 740 mA
Pout 4.92 W
Pin 7.92 W
E 62 %

10m
V=12,13 V
Irx 86.3 mA
Itx 950 mA
Pout 4.41 W
Pin 10.48 W
E 42 %

Value for R: 20

I hope that help you.
73

[Papa_Whisky]

Hi Luca,

Did you subtract your rx power from your tx power to obtain Pin?

[Luca66]

Hallo PW

Pin= Vin x (Itx-Irx)

73 Luca

[Titanus]

Wow, exept 10m very good values. I will receive this week my nanovna, than I will report my values. But untuned I made today (with only 11Volts) a qso on 15m from Vienna to Michigan, so it works already. Some picture of the tuned coils would be very helpful for all who are building it, because I saw one picture with the 10m coil somewhere in the net, and it works after 1 minute, only looking to the coil´s winding.

I love this little toy, makes great fun.

greetings from Vienna

[Luca66]

Hiallo Titanus,
I am attaching a picture of the rf board. As you can see, the coils with the most spaced turns are related to the highest bands. For the number of turns I followed the wiring diagram. The efficiency obtained is not exceptional for the 10m band, in any case we will never be able to exceed 70%. In this board I really like the choice of the surface soldered fet.
73 Luca

[Titanus]

T11 for 10m is now ok

IMG_5269 (1).jpeg (96.1 KiB) Viewed 1533 times

[Luca66]

Hallo Titanus, what are your values ​​now?
73 Luca

[Titanus]

Hi Lucas,

every Band is now above 60% eff , and between 4 and 6,4 Watts, so I am glad now. I will post later the exact values here. The NanoVna makes a lot of fun, a great unit!

[Titanus]

Here are the values, exept the 15m band, all above 60%:

20m..4W, 69%
17m..3,7W, 62%
15m..4,6W, 55%
12m..4,3W, 64%
10m..4,9W, 60%

Voltage was 12,5 V

greetings

[Luca66]

Ok, I saw your values ​​the first thing you have to tell me if the efficiency has been calculated or you read it on the display.

Be careful try to work to raise the efficiency to at least 70% calculated.

Having high output power as well as low efficiency is very dangerous.

You have to limit yourself to very short passes so as not to overheat the fet.

When you have calculated the efficiency work on the R value to update the value on the display to the true value.

Remember that these calibrations can also be done by powering via USB.

It's safer for the fet.

73 Luca

[Titanus]

Yes, thanks, the values are from the display unit itself. I know that I should calculate it. But the most important thing is, I speak with this little unit to many stations all over the world and it works perfect.

greetings