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Re: V6.1 Blown output transistors and pcb trace #v6 #ubitxv6-help

A Schwarz <ve7dxw@...>
 

[BITX20] V6.1 Blown output transistors

very disappointed with the design of the PA which lacks a thermal compensation circuit and is not stable. This is a fundamental design error and the unts are useless.

If it blew up it is not your fault and you should be able to get your money back, but no luck.


On Tue, Dec 28, 2021 at 6:31 PM A Schwarz <ve7dxw@...> wrote:
I feel sorry for all the people that bought the unit.
There is a circuit design issue with the unit and it should not be sold.

Since it is a do it yourself project the dealer (GigaParts) won't return the money either.

But on the Gigs pats reviews it has 5 stars, what a scam!

Alex

On Tue, Dec 28, 2021 at 4:09 PM A Schwarz via groups.io <ve7dxw=gmail.com@groups.io> wrote:
Singe ended PA are still having a heat issue and are very noisy - not recommended
 

Check this link, I solved the issue with the BangGood amp.
https://www.qsl.net/rf-seismograph/downloads/Building the MOSFET amp from Banggood.pdf

the mod requires the use of a NTC and that both transistors are on one heatsink


Re: V6.1 Blown output transistors and pcb trace #v6 #ubitxv6-help

A Schwarz <ve7dxw@...>
 

I feel sorry for all the people that bought the unit.
There is a circuit design issue with the unit and it should not be sold.

Since it is a do it yourself project the dealer (GigaParts) won't return the money either.

But on the Gigs pats reviews it has 5 stars, what a scam!

Alex


On Tue, Dec 28, 2021 at 4:09 PM A Schwarz via groups.io <ve7dxw=gmail.com@groups.io> wrote:
Singe ended PA are still having a heat issue and are very noisy - not recommended
 

Check this link, I solved the issue with the BangGood amp.
https://www.qsl.net/rf-seismograph/downloads/Building the MOSFET amp from Banggood.pdf

the mod requires the use of a NTC and that both transistors are on one heatsink


Re: V6.1 Blown output transistors and pcb trace #v6 #ubitxv6-help

A Schwarz <ve7dxw@...>
 

I feel sorry for all the people that bought the unit.
There is a circuit design issue with the unit and it should not be sold.

Since it is a do it yourself project the dealer (GigaParts) won't return the money either.

But on the Gigs pats reviews it has 5 stars, what a scam!

Alex


Re: V6.1 Blown output transistors and pcb trace #v6 #ubitxv6-help

A Schwarz <ve7dxw@...>
 

Singe ended PA are still having a heat issue and are very noisy - not recommended
 

Check this link, I solved the issue with the BangGood amp.
https://www.qsl.net/rf-seismograph/downloads/Building the MOSFET amp from Banggood.pdf

the mod requires the use of a NTC and that both transistors are on one heatsink


Re: Q90 emitter current slowly increases over 15 seconds

Paul Jensen
 

On Mon, Dec 27, 2021 at 07:18 PM, Ashhar Farhan wrote:
The Q90 is getting hot which increases the collector gain and leads to higher current. As the Q90 package is small, the heat doesn't get out very efficiently .
Should the bias resistor, R81, be increased from 2.7k to 3k?  That is a 10% increase.

Or would it be better to increase the emitter resistor from 100 to 110?

Thanks for the help.


Re: Raduino32. New batch of PCB #ubitxv6 #esp32 #raduino32

LAKSH MUTHU
 

On Mon, Dec 27, 2021 at 08:11 AM, <ramonlh@...> wrote:
Hola,

Some of you have asked me to send you all the necessary material for the operation. I would like to clarify some doubts in this regard.
Dear Ramon and the members of the group,
      Good Day and greetings to all. From the correspondences from Ramon, it is understood there may be some problems in shipping the Raduino32 as a completely assembled module. As such, I give my humble suggestions as below.
1. Ramon can kindly send the PCB  with components the components to the extent possible (without soldering connector and 7805) so that the PCB can be shipped as letter.
2. Ramon may please  give complete details as below
   a) Circuit diagram
   b) List of components soldered in the PCB
   c) List of components which are required in addition to the components already soldered  in the PCB and the details on how these additional components are to be connected to the board. (preferably with circuit diagram).
3,Ramon may kindly give hint on preferable variant of ESP32, ADS1115, DS18B20 temp probes etc; This will be helpful since for example ESP32 module  available in India is ESP32 Development board and as such will it be suitable or some other variant preferable.
   These are my humble opinions. Request members to  offer comments or further improved suggestions.
I hope Ramon will not mistake me for putting more requests and thrusts  to him.
Expecting early replies.
With regards,
MUTHU    VU2LMN


Re: V6.1 Blown output transistors and pcb trace #v6 #ubitxv6-help

Vakarcs Szilard
 

Here is a very useful single ended IRFP 250 PA project, delivered by YC3LSB:

https://yc3lsb.wordpress.com/2014/10/13/canary-dua-band-qrp-ssb-transceiver/

On 2021. 12. 28. 9:42, Vakarcs Szilard wrote:

I suggest not to use in push-pull any switching mode mosfet for RF purposes. Those transistors are simply not designed to work in AB mode. Mosfets are getting hot in a few milliseconds and there is no possibility to cool down such a small piece. Better is to use a single mosfet with higher voltage, such 24 V and 3 A. Special designed RF Mosfet transistors are working nice at 13.8 V, but they are way more expensive than those cheap fake IRF510.

Try to use IRFZ type mosfets, but all those shall be selected to be near identical in all properties.


On 2021. 11. 16. 13:16, Stan Mason wrote:
Thanks for that info, Raj.  Very helpful!  You’ve given me a great place to start and PA bias needs to be set regardless after replacing the IRF510s.

The primary reason I bought the uBitX was to have an open source platform with which to learn and experiment, so I’m going to read the ARRL Handbook sections on MOSFET characteristics and RF amplifier design before starting with the board.  

A previous commenter, Evan AC9TU, mentioned a file of transistor measurements from a V4 board you posted and speculated that the RF readings should be the same on the V6 board.  I’ll check that out also.

Stan K3PW


Re: V6.1 Blown output transistors and pcb trace #v6 #ubitxv6-help

Vakarcs Szilard
 

I suggest not to use in push-pull any switching mode mosfet for RF purposes. Those transistors are simply not designed to work in AB mode. Mosfets are getting hot in a few milliseconds and there is no possibility to cool down such a small piece. Better is to use a single mosfet with higher voltage, such 24 V and 3 A. Special designed RF Mosfet transistors are working nice at 13.8 V, but they are way more expensive than those cheap fake IRF510.

Try to use IRFZ type mosfets, but all those shall be selected to be near identical in all properties.


On 2021. 11. 16. 13:16, Stan Mason wrote:
Thanks for that info, Raj.  Very helpful!  You’ve given me a great place to start and PA bias needs to be set regardless after replacing the IRF510s.

The primary reason I bought the uBitX was to have an open source platform with which to learn and experiment, so I’m going to read the ARRL Handbook sections on MOSFET characteristics and RF amplifier design before starting with the board.  

A previous commenter, Evan AC9TU, mentioned a file of transistor measurements from a V4 board you posted and speculated that the RF readings should be the same on the V6 board.  I’ll check that out also.

Stan K3PW


Re: Q90 emitter current slowly increases over 15 seconds

Gerard
 

Hello,

There is a lot of reading on the subject.
Tests done with other transistors. Ex 2N5109, 2219; BC237 etc

See this link or type Q90 in the forum search bar


BITX20@groups.io | UBITX Q90 mod with BFR106

cdt


Re: Q90 emitter current slowly increases over 15 seconds

Ashhar Farhan
 

The Q90 is getting hot which increases the collector gain and leads to higher current. As the Q90 package is small, the heat doesn't get out very efficiently .
This is just a guess. 
- f


On Tue, Dec 28, 2021, 8:20 AM Paul Jensen via groups.io <wkend_traveler=yahoo.com@groups.io> wrote:
I swapped out Q90 with a BFR106 (as per Allison's power mod).  Also changed was the bias resistor R82 (from 1k to 2.7k).  No other changes were made.

After the Q90 change out, I noticed that holding the key down (CW mode), the output power would slowly climb - maybe a watt over 15 seconds.  Power was measured with a LP-100a power meter hooked up to a dummy load.

I traced it back to Q90.  Here are some voltage measurements noted on the circuit diagram.



The emitter voltage starts at 1.129 volts and slowly increases to 1.141 volts over 15 seconds.  Base stays the same at 1.85 volts.  Collector decreases from 12.71 to 12.69 volts.

No components are getting hot.  Does the same on all bands and modes.

What could cause this?


Q90 emitter current slowly increases over 15 seconds

Paul Jensen
 

I swapped out Q90 with a BFR106 (as per Allison's power mod).  Also changed was the bias resistor R82 (from 1k to 2.7k).  No other changes were made.

After the Q90 change out, I noticed that holding the key down (CW mode), the output power would slowly climb - maybe a watt over 15 seconds.  Power was measured with a LP-100a power meter hooked up to a dummy load.

I traced it back to Q90.  Here are some voltage measurements noted on the circuit diagram.



The emitter voltage starts at 1.129 volts and slowly increases to 1.141 volts over 15 seconds.  Base stays the same at 1.85 volts.  Collector decreases from 12.71 to 12.69 volts.

No components are getting hot.  Does the same on all bands and modes.

What could cause this?


Re: Trouble with uBitx v6 Audio

Michael Danese
 

Don't feel bad brother. Soldering was one of my best traits up until I turned 70 or so (I'm now 75), when my eyesight started to fail, my hands started to shake, and for some reason, the solder now a days doesn't seem to flow like the stuff I used years ago. Ad to that, components and their spacing have become much smaller.


I have been building small kits, like the PIXIE transceiver, just for practice, and destroyed two of them in the process.  


On Mon, Dec 27, 2021 at 4:47 PM Ben Madsen <ben@...> wrote:
Well, it ain't pretty, but it works.  I jumper wired a connection back to Q70 and the radio is operational again.  Thanks everybody!

I think I need to invest in some better solder working tools now so I don't break things when trying to fix them again in the future...

73,
Ben  


Re: ubitx v6 intermittent ft8 RX loss #ubitx6-help

Evan Hand
 

Tom,

I would make up another TX cable that goes to the mic input on the uBitx.  It could be that there is just enough resistance on the tip of the connector that it confuses the Nano.  Isolating that connection is the other thing that happened when I connected with the isolation transformers.  This is assuming that you are using CAT for the PTT of the uBitx.

73
Evan
AC9TU


Re: Trouble with uBitx v6 Audio

Ben Madsen
 

Well, it ain't pretty, but it works.  I jumper wired a connection back to Q70 and the radio is operational again.  Thanks everybody!

I think I need to invest in some better solder working tools now so I don't break things when trying to fix them again in the future...

73,
Ben  


Re: ubitx v6 intermittent ft8 RX loss #ubitx6-help

Tom Christian
 

Thanks to all for replies.  I'm pretty sure the USB cable & antenna are not the issue because an older ubitx seems to work ok.

Evan, when receive stops on the waterfall, removing the receive cable from the jack reveals dead air on the speaker (as opposed to confirmed good signals on the speaker previously).  So receive on the radio itself is not working.  BUT..... I did find a new way to clear the problem by doing this troubleshooting.  I accidentally unplugged the TX cable from the jack instead of RX at first.  When I removed/replugged it, the radio relay (probably K3) made a normal (louder) clicking recycle and then RX started working again.  Further similar troubleshooting when RX dies by removing/replugging the TX cable from the jack shows: 1) when the radio relay recycles with a normal loud clicking, then RX starts working again; 2) when the radio relay has a weak clicking (less loud), then the RX problem still exists.  The original problem started happening whenever I would notice that TX would start having weak relay clicking sounds.  I still don't know if those weak relay clicking sounds were from radio board or raduino (but it seems more likely to me that it's relay related on the radio board).  Tapping K3 and the other relays during the problem doesn't seem to help.  Any additional thoughts would be appreciated.  Thanks!
Tom
AB7WT


Re: Trouble with uBitx v6 Audio

Ben Madsen
 

Haha...

Lesson learned.  I had it working for about 5 minutes.  After replacing Q70 with a generic NPN I was still seeing 0v on the base.  I double checked the voltage on R50 and it was not passing voltage so I decided I'd replace that one and it finally came to life.  Yay!

Then I decided I should clean things up and put the original Q70 back...  in doing so, I managed to take off one of Q70's solder pads and now I'm back to a radio I can't use...  This radio is definitely proving to be learning experience I bought it for!  :-D

73
-Ben


Re: ubitx v6 intermittent ft8 RX loss #ubitx6-help

Arv Evans
 

Is the antenna intermittent?


Re: Raduino32. New batch of PCB #ubitxv6 #esp32 #raduino32

ramonlh@...
 

Hi, 
The module must have 2x15 pins with this arrangement


Re: Raduino32. New batch of PCB #ubitxv6 #esp32 #raduino32

ramonlh@...
 

Hola,

Some of you have asked me to send you all the necessary material for the operation. I would like to clarify some doubts in this regard.

I will send the PCB with all the components soldered. For its operation, it is necessary to add at least one ESP32 module. This achieves minimal performance. There are other additional functions that require additional components that are readily available.

In principle, I have not considered the possibility of supplying a complete kit with all the elements, mainly because a PCB can be sent by post as a simple registered letter. If many items are added, it would be necessary to prepare a package with the consequent complications in terms of billing, customs and taxes and I do not have the capacity to do so. Should any kit or equipment vendor wish to do so, I will be happy to provide all the necessary design, knowledge and support. I am retired and I want to continue enjoying without obligations 😉😉😉.

However, if anyone is having a hard time getting any of the modules, I can gladly get it and ship it to them.

For the operation of the S-meter and SWR meter it is necessary to add an ADC converter module of the type ADS1115 and another one for the operation of the voltage and current meter.

To use Serial port 2 it is necessary to add a serial to USB module.

For the temperature control function of the power transistors and the regulator, 3 probes of the type DS18B20 must be added.

Below this message I add example links to buy these components.

Saludos,

Ramón EA4GZI


ESP32 module 30 pins



https://es.aliexpress.com/item/32824611594.html?spm=a2g0o.productlist.0.0.50c918e1eceipv&algo_pvid=26b274ea-ea43-460f-84d1-2d9c7a7189e7&algo_exp_id=26b274ea-ea43-460f-84d1-2d9c7a7189e7-23&pdp_ext_f=%7B"sku_id"%3A"64885069741"%7D&pdp_pi=-1%3B7.85%3B-1%3B-1%400.210000%3BEUR%3Bsearch-mainSearch

 

ADS1115 module

https://es.aliexpress.com/item/1005002947587065.html?spm=a2g0o.productlist.0.0.15b96251dZeMeG&algo_pvid=89f81140-d04b-4a93-95ee-fb4c18eee247&algo_exp_id=89f81140-d04b-4a93-95ee-fb4c18eee247-24&pdp_ext_f=%7B"sku_id"%3A"12000022914420843"%7D&pdp_pi=-1%3B3.97%3B-1%3B-1%400.210000%3BEUR%3Bsearch-mainSearch

Serial to USB adapter

https://es.aliexpress.com/item/32273550144.html?spm=a2g0o.productlist.0.0.3e965c56EGx7rP&algo_pvid=6c81432a-61d9-46b6-a5d0-028fa74b9f62&aem_p4p_detail=20211227080228966803221915380022334068&algo_exp_id=6c81432a-61d9-46b6-a5d0-028fa74b9f62-9&pdp_ext_f=%7B"sku_id"%3A"12000021370119598"%7D&pdp_pi=-1%3B1.83%3B-1%3BEUR+0.51%400.210000%3BEUR%3Bsearch-mainSearch

DS18B20 temp probes

https://es.aliexpress.com/item/1005002992339397.html?spm=a2g0o.productlist.0.0.2f2e24aacLFn9x&algo_pvid=2af9bb37-07ef-438e-a62a-0c40d978b97b&aem_p4p_detail=20211227080756800696705305140022379294&algo_exp_id=2af9bb37-07ef-438e-a62a-0c40d978b97b-8&pdp_ext_f=%7B"sku_id"%3A"12000023110270168"%7D&pdp_pi=-1%3B5.28%3B-1%3BEUR+1.64%400.210000%3BEUR%3Bsearch-mainSearch


Re: LED/LDR AGC mod for uBitx V6

K4LXY
 

Paul
Thanks for the update and info.  The configuration you ended up with seems to me the most logical one.  I connected to the speaker because I wanted to sense the signal after the audio CW filter I added so that the AVC wouldn't be triggered by other signals within the wide passband of the uBitx.
Nice job building the board.

Howard

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