very low power and efficiency on my (tr)usdx

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peppone
 

Posts: 24
Joined: 05 Aug 2022, 09:16

very low power and efficiency on my (tr)usdx

Post by peppone »

Hi, after many time i calibrated an antenna and connected my (tr)usdx to test the power and swr but i have very bad values...when i took the picture power supply was 12v/7A and antenna load at the frequency was 50ohm...
how can i resolve this problem?
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trusdx.jpg
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dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: very low power and efficiency on my (tr)usdx

Post by dl6sez »

Hello Peppone,

what do you think about checking your frequency setting?
You are trying to send at 13,599 MHz! No chance so far for a power output with standard LP filter... you will probably kill your FETs....

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
peppone
 

Posts: 24
Joined: 05 Aug 2022, 09:16

Re: very low power and efficiency on my (tr)usdx

Post by peppone »

Hi Chris,
at 14.100 power was 0,08w and efficiency was about 3 and it was the first tx of radio,after i tried at differents frequencies until 13.500 and this was first time the radio went on tx after i changed all FETs, before power was 0.00...

73 Peppone
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: very low power and efficiency on my (tr)usdx

Post by dl6sez »

Okay Peppone,

you bought a kit and assembled all on rf pcb by yourself as i understood by your post....
Than probably if the toroid inductances are higher, your optimum output power can be around 13,599MHz frequency.
Have you measured real current consumption on TX with a multimeter or power supply with current meter?
Have you measured output power with rf power meter (or voltage on an oscilloscope) at a real 50Ohm dummyload? Tuned antenna should not be taken for measurements especially for our class-E amplifier stage. If there is about 0,5A on TX (CW straight key) you should see at least 2W real power.
If this is not the case check solder joints, especially on toroid joints, resolder if necessary (also on measurement toroids T1 and T2)
If you have changed your FETs, than probably driver 74ACT00 could also be damaged!
Remember that we have many many fake/wrong BS170 FETs in the supply chains today!
You probably replaced your damaged ones with fake ones.

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
peppone
 

Posts: 24
Joined: 05 Aug 2022, 09:16

Re: very low power and efficiency on my (tr)usdx

Post by peppone »

Hi Chris,
I am not a tchnician, I am an hobbyist so i have not an oscilloscope, i have only an old digital multimeter and a NanoVNA...
Yes, I assembled the radio by myself, it is very good in rx , maybe i fried original bs170 in the euphoria of the first test, probably pushing tx button without antenna. when i bought new bs170 i watched a video on youtube about testing fets with a multimeter on diode mode, in the video he showed how to test the diode inside fet and how to test the gate...in my bs170 only diode test was ok, i think i bought fake/wrong bs170 even if the sheet on seller's page was the same as that of the BS170 Onsemi/Fairchild...I checked solder joint many times and resoldered T1 and T2 to be sure ( all toroids pin have been scratched with sand paper before welding on board)...

73 de Peppone
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: very low power and efficiency on my (tr)usdx

Post by dl6sez »

Hello Peppone,

so sure your FETs are not real BS170s.
Go and find a Ham Radio friend in your area to help you with a component tester (around 15Euros direct from China, T4 component tester). You need more measurement capabilities to solve this (tr)uSDX problems. Remember also 74ACT00 could have been killed.

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
peppone
 

Posts: 24
Joined: 05 Aug 2022, 09:16

Re: very low power and efficiency on my (tr)usdx

Post by peppone »

Hi Chris, component tester arrived. the bs170 seems to be good
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bs170Test.jpg
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dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: very low power and efficiency on my (tr)usdx

Post by dl6sez »

Hello Peppone,

here we have it:
sorry but at your "BS170" Drain and Source is changed, the pinout is like a 2N7002!
So i think you have bought fake BS170s which are 2N7002 or other similar FETs.

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: very low power and efficiency on my (tr)usdx

Post by dl6sez »

Not the best picture but a real BS170, round up flat down:
20221031_220929_1.jpg
20221031_220929_1.jpg (249.16 KiB) Viewed 1837 times
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
peppone
 

Posts: 24
Joined: 05 Aug 2022, 09:16

Re: very low power and efficiency on my (tr)usdx

Post by peppone »

Hi Chris, in another post Manuel had told me that some new bs170 have S and D pins inverted and i had to test and mount them reversed, obviously he could not know that the values were wrong, so my BS170 are not only with inverted S and D pins but with differents values of capacity and voltage...so the real problem is this difference in values...
Are this good BS170?
https://it.rs-online.com/web/cp/1241745 ... ?pst=BS170

73 de Peppone
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: very low power and efficiency on my (tr)usdx

Post by dl6sez »

Hello Peppone,

for the BS170: there are not others with changed Drain Source this is not true, these are chinese false printed BS170 Mos-FETs like the 2N2007 with the pinout like yours.
If you look at the official Onsemi Datasheet these are the only real BS170s (their FET). All my "BS170" are like there pinout. If they are real Onsemi than they for sure have their Onsemi specs, but many other manufacturers are selling these simple Switching Fets which are used for simple circuits.
In none of these circuits they are forced to switch with frequencies in MHz.... the capacities don't really play a role there. In our application it is extremely important that the input and output capacities are kept within specs, otherwise one has to change the capacities of the class E filter if the Fets are changed....
I have had two suppliers for BS170, Mouser and a small company on Ebay a German seller (old stock).
But i can not tell if one or both of these two are 100% genuine, but the Pinout of DGS with round up 1,2,3 in the Tester is the same for both like in the original Datasheet.
So Peppone i can't tell you wether RS is selling good ones now.... for sure nobody can tell you!
The problem is for this extremely cheap simple and normally not used for RF no one of the sellers knows where the Fet he buys and sells really come from.
We have such problems with other electronic components also.... thanks chinese selling policies.

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
peppone
 

Posts: 24
Joined: 05 Aug 2022, 09:16

Re: very low power and efficiency on my (tr)usdx

Post by peppone »

I understand...with this component it is like a lottery :lol: 73 de Peppone
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: very low power and efficiency on my (tr)usdx

Post by dl6sez »

I like China :lol:
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
peppone
 

Posts: 24
Joined: 05 Aug 2022, 09:16

Re: very low power and efficiency on my (tr)usdx

Post by peppone »

hi, after a few month finally i mounted genuine fairchild BS170 on my trusdx, but the problem is the same only an 0.20 w output in cw tx mode with a 1.3 swr antenna at 14.060 mhz, so the problem are not the bs120... i assembled this radio in september 2022 and I could never have the pleasure of transmitting something... only receive...what must I do?
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