Topics

No power out


Michael Davis <maddmd818@...>
 

Hi all, although not a new subject, now that there are many more users, I'm hoping to get some direction to fix the problem. My friend had his Bitx working but added a speaker and accidently hit the PA/IRF510 tab to the frame of the speaker. He had added a 2 amp fast acting fuse and it blew. 4-5 fuses later, he realized where the short was but the radio still won't transmit. He replaced the PA, still no luck. If you have any experience in this area of the Bitx, what other component(s) might have been affected by this error? He tried to set bias again but gets no bias current reading. Thanks


John Backo
 

You need first to measure the voltages on the board. If you get no current gain by adjusting RV1, then probably you have no gate voltage.
Start by connecting your power supply to the board with an ammeter in the line. Is there any current draw at all?

It should be 5v or so at the top of RV1. Do not allow more than 4v on the gate of the IRF510!
Zero volts means a bad 5v VR. But make sure there is input voltage to the VR as well. It is possible
that a trace or two was burnt. Bad regulators or open traces are the two most likely causes
of the problem.

It is also possible that some or all of the other VRs on the board are defective. Check all the voltages
with an input of about 9v. Watch out for shorts! Most of the board will take 9v. Some of it will not.

If all that looks ok, check for cold solder joints. A sudden spike might cause one to show up.

Hope this helps.

john
AD5YE


Brian Lewis
 

If he can't get it working I'd sell my bitx40 board. My setup came with a bad raduino board and I can't replace just that.  


John Backo
 

No, you can't...but you can easily build a substitute with all the parts and methods easily available.
And you can build a VFO to handle frequency any time.

john
AD5YE


Jerry Gaffke
 

If the display works, it's likely in the Si5351 somehow.  Replacing just that $1 USD chip would be tough, it has some awfully small pins.  Best path forward might be to buy an Si5351 board from etherkit.com or adafruit.com, around $10 USD.  If it arrived non-functional you might try sending an email to hfsignals at gmail dot com, but cost and time to ship both ways makes this hardly worth the bother.  If you want to sell it, you might name a price.


On Sun, Mar 19, 2017 at 04:07 pm, Brian Lewis wrote:

If he can't get it working I'd sell my bitx40 board. My setup came with a bad raduino board and I can't replace just that.  

 


Bob Benedict, KD8CGH
 

I also shorted my IRF150m to ground and and blew a fuse. After that I had no power out.

Following a tip on this board I traced the voltage from PA PWR1 through L8 I found that there was no voltage at T7. The circuit board trace was blown. I wired a jumper from L8 to pin 6 of T7. I then had again had PA voltage at the Drain of the IRF150 and power out on transmit.




https://groups.io/g/BITX20/topic/bitx40_transistor_voltage/4336465?p=,,,20,0,0,0::Relevance,,Voltage+measurements,20,2,0,4336465


 

Connect the PA power and trace with multimeter is the 12V is there at

L8, T7 and IRF drain.

If you blew the fuse then you may have blown a PCB track.

Raj, vu2zap

At 19/03/2017, you wrote:

Hi all, although not a new subject, now that there are many more users, I'm hoping to get some direction to fix the problem. My friend had his Bitx working but added a speaker and accidently hit the PA/IRF510 tab to the frame of the speaker. He had added a 2 amp fast acting fuse and it blew. 4-5 fuses later, he realized where the short was but the radio still won't transmit. He replaced the PA, still no luck. If you have any experience in this area of the Bitx, what other component(s) might have been affected by this error? He tried to set bias again but gets no bias current reading. Thanks


Marc Jones
 


I'm definitely going to add a insulating  washer  kit to mine ... I've read no end of posts like this  now ..... I hope you get the problem sorted .

Regards

On Sun, 19 Mar 2017 at 18:17, Michael Davis
<maddmd818@...> wrote:

Hi all, although not a new subject, now that there are many more users, I'm hoping to get some direction to fix the problem. My friend had his Bitx working but added a speaker and accidently hit the PA/IRF510 tab to the frame of the speaker. He had added a 2 amp fast acting fuse and it blew. 4-5 fuses later, he realized where the short was but the radio still won't transmit. He replaced the PA, still no luck. If you have any experience in this area of the Bitx, what other component(s) might have been affected by this error? He tried to set bias again but gets no bias current reading. Thanks


Rubens Kamimura
 

Hi all,
 
No Power Out in: 10m, 12m and 15m.
 
Note: There was a power fluctuation problem in digital mode - JTDX (FT8), observed at 40m, with the help of the group, I checked the option "Fake It" (JTDX), and it was corrected.
 
But what is happening? I have reception at 10m, 12m and 15m, but with no RF output (0 Watts).
On the other tracks I have TX normally.

TU

73's
py2pvb
Rubens


Evan Hand
 

I will assume that this is a v6.  Based on that assumption, I would verify that one of the LPF filter relays has a bad contact on the NO position or it may be stuck on, as all are off for the 10m band (always in the chain, so it not likely to be that filter).  

Can you verify that all three of the other bands are working?  80, 40, and 20.  The order through the chain from the PA to the antenna is 20, 40, 80 that are switched, and then the 10-meter filter that is always in the chain.

It could also be a stuck 20m LPF relay, as that is the highest frequency below 10m.  Verify that that relay is not pulling in and is not stuck on.

Just some suggestions.
73
Evan
AC9TU


Rubens Kamimura
 

Evans, and group.

Grateful for the help.

I see in the diagram that TXA drives relay KT1, TXB the KT2 and TXC the KT3.

For 10, 12 and 15m how should these relay combinations be? Do you tell me that 10m everyone is in off mode? So it only depends on the KT1 relay ("NC" ratings 12-14, and 3-5) switched off! ... It is?
-- 
73's PY2PVB

Rubens Kamimura


Em seg., 18 de jan. de 2021 às 13:18, Evan Hand <elhandjr@...> escreveu:

I will assume that this is a v6.  Based on that assumption, I would verify that one of the LPF filter relays has a bad contact on the NO position or it may be stuck on, as all are off for the 10m band (always in the chain, so it not likely to be that filter).  

Can you verify that all three of the other bands are working?  80, 40, and 20.  The order through the chain from the PA to the antenna is 20, 40, 80 that are switched, and then the 10-meter filter that is always in the chain.

It could also be a stuck 20m LPF relay, as that is the highest frequency below 10m.  Verify that that relay is not pulling in and is not stuck on.

Just some suggestions.
73
Evan
AC9TU


Evan Hand
 

The KT relays should be off, the K1 and K3 will be on for 10m transmit.  What I was trying to say is that the three relays that select the bandpass filter to use are all off, not the other two relays to control TX in general.

73
Evan
AC9TU