Форум Радиолюбителей КВ - УКВ

Today this board is fully debugged and in the new version of the low-pass filter it is already made in a three-loop version, which gave higher harmonic suppression and it came out better than 65 dB.
This board configuration was conceived for Anvelin sdr, that is, in fact, it is an analogue of Anan-7000, this design can also work with Odyssey-2, not a big firmware correction for this transceiver here https://eu2av.ru/viewtopic.php?f=4&t=151
The board can also work Orion-MK2.
-Now some information about the design itself, the board is made in four layers and has a size of 230x200.
-The input power is enough 1 watt per input, if you reduce the feedback in the output stage, these are resistors R56, R57, R59, R62, then you can bring it up to 0.5 watts at the input. Schematic and BOM, you can also see the BPF and LPF graphs there:
Frequently asked questions on self-assembly can be asked here in this thread.
Below are the photos for the manufacture of the output transformer, for the manufacture of the windings I used the 16AWG wire purchased here https://www.aliexpress.com/item/1005001611628766.html
I used the braid from the RG316 cable, that is, the braid needs to be threaded into the 16AWG wire, so we get a homemade 15ohm cable, which fits much better than 25ohm.
Нажмите на спойлер что бы увидеть фото. Further on the SWR meter and the directional coupler, it is desirable to reduce the connection with the output line of the transmitter, for this I used the RG402 cable, below by clicking on the spoiler the manufacturing process in the photo, I think it will be well understood

Small addition It is possible to use 12.5ohm coaxial cable in output stage transformer. You can buy it here: https://www.ebay.com/itm/203781564667?h ... SwV65fawFy
As well as you can buy it directly from seller online shop here: https://www.sv1afn.com/en/rf-cables-1/1 ... ter-1.html
Not cheap, your choice

Just got partly soldered BPF/PA boards, most fresh version More information later

Dear Yury,
last year i have souccessfully implemented your Amplifier old version.
Now i have completed the Rev 3.6.0. I have already tested all the filters with spectrum anayzer.
Amplifier has been now installed in the enclosure.
For the components i have follow your BOM 3.6.1 2022-05-04.
I have vefiried that there are several vatiations in the mosfet polarization, versus my other amplifier and the last scehmatics available "BPF-PA-Rev-3.6.0-Anvelina-SDR".
L57 and 57 has been shorted as indicated in the bom "no/set".
In the enclosed pictures is possible to see clearly the resistors values.
Power on at 13,8V
When the trimmers RV1 and RV2 are fully counterclockwise (10Kohm) gates are at about 0V and D52 zener is at 8V.
When i rotate comletely clockwise only RV2 Voltage at Mosfet gate is only 2,6V and voltage at zener D52 are 7,775V
When i rotate comletely clockwise only RV1 Voltage at Mosfet gate is only 3,3V and voltage at zener D52 are 8V
I have seen that in my previous amplifier the correct polarization is about 4,5V
Please let me know your suggestion and maybe some test in order to found the reason.
Many Thanks, 73
Greatings from Italia
Luca IK2LRN

Luca Hello glad to hear! The fact is that now it is very difficult to get the original rd100, those from China have lower gate voltage, usually 2.6-2.7v. For the original transistors rd100, the operating voltage at the gates goes within 4.1-4.3v.
You need to pick up resistors R48, R51, for example, put 5.1K each.

Hello Yury
thanks for your reply.
I have solved the Mosfet polarization problem.
R47/48 that was 1kohm : the value indicated in the schematic, whereas R60/61 was set at 33kom as BOM instead of 3kohm.
My original Mitsubishi mosfet than has been burned!
The gate resistance of burned mosfet is 500ohm than it was impossible to set the bias voltage !

I have replaced the mosfet with chinese one. The gate voltage required is about 2,2 volt instead of about 4,2 volt, required for Mitsubishi mosfet.
I have set the polarization resistors as R47/48 7,5k and R60/61 4,7k
Now i have set bias at 1A for each mosfet.
Unfortunately power max power output is only 25W.
I have to investigate about it, next weekend .The filters was previously aligned with spectrum analyzer.
I will compare the measurements with my working amplifier.
73, thanks
Luca

Luca Hello! In the latest circuits, the values \u200b\u200bof the resistors in the binding of the transistor gates were changed, so compare this carefully. My current per transistor will be 2.5 amperes, that is, the total quiescent current for two transistors is 5 = amperes. With a lower current, it also works acceptable, but noticeably worse, and the input resistance at (5A) is more preferable. Keep up to date, I think this problem will be solved.

Hi Yury,
now i have more than 100W in all bands except to 6m: the output power is only 35W with power consumption about 5A
At 6m with my previous amplifier i have obtained 80w.
I have double checked the output filter with spectrum analyzed and it is OK. Also the RF level at the mosfet gate is about the same of the other bands.
Than i suppose that the problem is related to the tuning circuit with T3, C199, C201, C202 but i don't know how to properly adjust it.
Can you help me ?
Thanks, 73
Luca IK2LRN

Luca Hello! Tell me what condensers C200, C 198?
Try replacing them with 100p. Make sure that the output power at the output of the SDR board is at least 1 watt.

Hi Yury,
i have removed C198 and C200 without replacing it. Power output is still about 35W.
I have verified that avelina output is about 1W
Like i have explained in my previous post signal level at mosfet gate is allmost the same at all band , including 50Mhz. Than i suppose that up to the mosfet gate everithing is OK.
I have applied 2W input with signal generator followed to a small amplifier and now output is about 47W
With my other working amplifier with 1W input i obtain 80W.
MOSFET are original purchased at Mini-Kits Australia: same source of my working amplifier.

What do you suggest to do ?

Thanks

Luca

Hi Luca, It is not worth removing these capacitors, they are needed in order to achieve a good or acceptable frequency response from 1.8-50 MHz. I suggest trying to play with the denominations C 199,201,202. I use ATC100 capacitors. I have a similar result(80watt), in some instances of the amplifier it turned out to achieve a power of 100 watts on a 6m band.

Hi Yury, i have removed all the capacitors but it seams that above 45Mhz there is an impedance mismatch.
I have connected spectrum analyzer at the output of the final transformer, with mosfet bias off.
If i disconnect the transformer the low pass filter is ok but if i connect the trasformer the frequency above 45Mhz are dropped. The situation is better if i remove the capacitors but not enough.
I have decided to rebuild the transformer. I have used super expensive 15ohm impedance silver cable (20 euro per meter).
Please see the attached picture of the removed transformer with super cable.
I have decided to use 4 peaces of cables soldered together like my previous amplifier, instead of
uncut cable.
73
Luca

Dear Yury,
i have rebuild the final transfomer and replace c200, C198, C199, C201, C202 and 50Mhz low pass filter capacitors with ATC100 capacitor. There is a supplied of that capacitor directly in my city.
The output power is increaed form 35 to 43W at 50MHz
Than i have replaced C201 first from 100 to 180pF and the power is increased to about 48W at 50MHz
I have replaced the C201 capacitor with 330pF ATC capacitor and now output power is 60W !
Not good as my previous amplifier buid, using value in the schematic, that reach 80W
In the others band the performance is still very good or even better !: up to 100W. Power at 28MHz is slightly deceased but can be adjusted again to 100W with Power Amplifier thetis bias.
Before to try to increase again C201 i would like to know your opinion.I don't know if it could damage the mosfet
Maybe modify before the number of turns of T3 ? (now the turns are 12 instead of 13 in the schematic) or increase before C201 at 390pF ?
Please take into accout that my implementatins use the components referred in Rev-3.6.0 SDR_BPF1.BPF2.PA100Watts BOM.
The only variation is bias resistors R60 and R61 that are 4,7Kohm. also R48 has been changed for original MOSFET bias 3,9V (about 1A bias for each MOSFET like my previous amplifier)

Thanks, 73

Luca

IK2LRN