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UbitX no RF out SSB and CW

 

Hi all,

I'm somewhat new but I've spent a lot of time looking on these forums for a solution to my issue. As a disclaimer, I started this project knowing almost nothing about electronics, save ohms law and the like.?

When I first got my ubitx I plugged it in WAY before I ever should have, ie before I was even halfway done. This blew my U1, or it shipped faulty, either way that has been replaced. Now I have it at a point where it should be working perfectly but, of course, it's not. Connected to a dummy load and power meter, I get 0 watts out when yelling into the mic, as well as when shorting the key jack to ground. With the mic, it switches into TX and I can hear the relay click. When in CW, I get the click, it's switches to CW, and I hear the side tone. Still, no power out.

I have a multimeter, but again I'm quite new to all this so use laymens terms if possible. Thanks!

-Evan Clark?
 

Since you can hear the sidetone, you have U1 working.

Some people have had trouble with the center pin of a coax BNC connector not connecting well
with the BNC socket provided with the kit.? ? Maybe go around that BNC socket somehow during initial tests,
or at least verify the center pin is making a good connection by using an ohmmeter.
?
Does the receiver work?
You will need maybe 60 feet of wire out the window for an antenna before it will hear much.

Do you have some other shortwave receiver around, preferably one capable of receiving SSB transmissions?
With the uBitx, does this other receiver hear a carrier at about 11.997mhz when placed near the uBitx?
You should hear that during both transmit and receive.

Does this other receiver hear attempts at transmitting CW into a dummy load when placed near the uBitx?
Does it hear SSB transmissions from the uBitx when placed near?
Could be that the transmitter is mostly working, but the final amplifier is not.

Jerry, KE7ER


On Wed, Aug 22, 2018 at 01:16 PM, Evan Clark (OSC) wrote:
Hi all,
?
I'm somewhat new but I've spent a lot of time looking on these forums for a solution to my issue. As a disclaimer, I started this project knowing almost nothing about electronics, save ohms law and the like.?
?
When I first got my ubitx I plugged it in WAY before I ever should have, ie before I was even halfway done. This blew my U1, or it shipped faulty, either way that has been replaced. Now I have it at a point where it should be working perfectly but, of course, it's not. Connected to a dummy load and power meter, I get 0 watts out when yelling into the mic, as well as when shorting the key jack to ground. With the mic, it switches into TX and I can hear the relay click. When in CW, I get the click, it's switches to CW, and I hear the side tone. Still, no power out.
?
I have a multimeter, but again I'm quite new to all this so use laymens terms if possible. Thanks!
?
-Evan Clark?
 

Jerry, thanks for the response! I have an Icom 740, which is unable to tune to 11.997 HMz, but I am able to pick up the CW tone transmitted from the ubitx when tuned to the same frequency. Good news! In addition, I am able to receive with the ubitx the tone when generated from the 740. So I must be TXing milliwatts? My first thought would be to replace the IRF510s.


On Wed, Aug 22, 2018 at 1:46 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
Since you can hear the sidetone, you have U1 working.

Some people have had trouble with the center pin of a coax BNC connector not connecting well
with the BNC socket provided with the kit.? ? Maybe go around that BNC socket somehow during initial tests,
or at least verify the center pin is making a good connection by using an ohmmeter.
?
Does the receiver work?
You will need maybe 60 feet of wire out the window for an antenna before it will hear much.

Do you have some other shortwave receiver around, preferably one capable of receiving SSB transmissions?
With the uBitx, does this other receiver hear a carrier at about 11.997mhz when placed near the uBitx?
You should hear that during both transmit and receive.

Does this other receiver hear attempts at transmitting CW into a dummy load when placed near the uBitx?
Does it hear SSB transmissions from the uBitx when placed near?
Could be that the transmitter is mostly working, but the final amplifier is not.

Jerry, KE7ER


On Wed, Aug 22, 2018 at 01:16 PM, Evan Clark (OSC) wrote:
Hi all,
?
I'm somewhat new but I've spent a lot of time looking on these forums for a solution to my issue. As a disclaimer, I started this project knowing almost nothing about electronics, save ohms law and the like.?
?
When I first got my ubitx I plugged it in WAY before I ever should have, ie before I was even halfway done. This blew my U1, or it shipped faulty, either way that has been replaced. Now I have it at a point where it should be working perfectly but, of course, it's not. Connected to a dummy load and power meter, I get 0 watts out when yelling into the mic, as well as when shorting the key jack to ground. With the mic, it switches into TX and I can hear the relay click. When in CW, I get the click, it's switches to CW, and I hear the side tone. Still, no power out.
?
I have a multimeter, but again I'm quite new to all this so use laymens terms if possible. Thanks!
?
-Evan Clark?
 

I would not just randomly replace stuff.
You have dozens of parts to suspect.
And it worked when shipped.

Do you have 12v applied to the IRF510's when transmitting?
You should see 12v to ground on the tabs of the IRF510's when transmitting.
Could be as simple as not having 12v wired to the PA-PWR pin of that 3 pin uBitx connector as shown in the WireUp diagram on hfsignals.?

You should have a 50 ohm dummy load hooked up when testing the transmitter.
Output is typically 10 watts, but if you only use it for short periods at less than 50 percent of the time,
a 5 watt dummy load won't get too hot.

I doubt it will damage anything to test the transmitter without a dummy load, but it could.

Jerry


On Wed, Aug 22, 2018 at 02:06 PM, Evan Clark (OSC) wrote:
Jerry, thanks for the response! I have an Icom 740, which is unable to tune to 11.997 HMz, but I am able to pick up the CW tone transmitted from the ubitx when tuned to the same frequency. Good news! In addition, I am able to receive with the ubitx the tone when generated from the 740. So I must be TXing milliwatts? My first thought would be to replace the IRF510s.
toggle quoted message. . .
 

Do a thorough visual inspection of the power amp, everything from Q90 out to the antenna jack.
Including the antenna jack.

The toroids and hand wound and installed by hand.
A bad solder job due to enamel remaining on the magnet wire could do this, you could check for that with an ohmmeter.
Or a broken wire due to jostling when shipped

Try hooking a 50 ohm dummy load and wattmeter between T11 pin 5 and ground.
That way we go around the transmit low pass filters and the relays at KT1,2,3 that select one of the filters.

Jerry


On Wed, Aug 22, 2018 at 02:20 PM, Jerry Gaffke wrote:
I would not just randomly replace stuff.
You have dozens of parts to suspect.
And it worked when shipped.

Do you have 12v applied to the IRF510's when transmitting?
You should see 12v to ground on the tabs of the IRF510's when transmitting.
Could be as simple as not having 12v wired to the PA-PWR pin of that 3 pin uBitx connector as shown in the WireUp diagram on hfsignals.?

You should have a 50 ohm dummy load hooked up when testing the transmitter.
Output is typically 10 watts, but if you only use it for short periods at less than 50 percent of the time,
a 5 watt dummy load won't get too hot.

I doubt it will damage anything to test the transmitter without a dummy load, but it could.

Jerry
 

Ok I may be onto something. I removed the DC connector and opted for Anderson Power Poles for battery power usage. I did not do the proper research apparently (took 5 seconds to look at the wireup). In my swap, I connected the red to red and black to black. This left the brown wire (PA power) unconnected... not sure what my thought process was there. Anyways, I have not had 12 volts on the finals. Despite this, I still have 12 volts on the finals.


On Wed, Aug 22, 2018 at 2:26 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
Do a thorough visual inspection of the power amp, everything from Q90 out to the antenna jack.
Including the antenna jack.

The toroids and hand wound and installed by hand.
A bad solder job due to enamel remaining on the magnet wire could do this, you could check for that with an ohmmeter.
Or a broken wire due to jostling when shipped

Try hooking a 50 ohm dummy load and wattmeter between T11 pin 5 and ground.
That way we go around the transmit low pass filters and the relays at KT1,2,3 that select one of the filters.

Jerry

On Wed, Aug 22, 2018 at 02:20 PM, Jerry Gaffke wrote:
I would not just randomly replace stuff.
You have dozens of parts to suspect.
And it worked when shipped.

Do you have 12v applied to the IRF510's when transmitting?
You should see 12v to ground on the tabs of the IRF510's when transmitting.
Could be as simple as not having 12v wired to the PA-PWR pin of that 3 pin uBitx connector as shown in the WireUp diagram on hfsignals.?

You should have a 50 ohm dummy load hooked up when testing the transmitter.
Output is typically 10 watts, but if you only use it for short periods at less than 50 percent of the time,
a 5 watt dummy load won't get too hot.

I doubt it will damage anything to test the transmitter without a dummy load, but it could.

Jerry
 

Sorry if the last bit of the previous post was phrased oddly. I have connected the brown wire on the power in to the red one, so I am getting 12v to the finals. I now have 12v between pins 1 and 2 as well as 2 and 3. I'm still not seeing even a budge on the power meter, though.


On Wed, Aug 22, 2018 at 2:55 PM Evan Clark (OSC) <evanclarkie@...> wrote:
Ok I may be onto something. I removed the DC connector and opted for Anderson Power Poles for battery power usage. I did not do the proper research apparently (took 5 seconds to look at the wireup). In my swap, I connected the red to red and black to black. This left the brown wire (PA power) unconnected... not sure what my thought process was there. Anyways, I have not had 12 volts on the finals. Despite this, I still have 12 volts on the finals.

On Wed, Aug 22, 2018 at 2:26 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
Do a thorough visual inspection of the power amp, everything from Q90 out to the antenna jack.
Including the antenna jack.

The toroids and hand wound and installed by hand.
A bad solder job due to enamel remaining on the magnet wire could do this, you could check for that with an ohmmeter.
Or a broken wire due to jostling when shipped

Try hooking a 50 ohm dummy load and wattmeter between T11 pin 5 and ground.
That way we go around the transmit low pass filters and the relays at KT1,2,3 that select one of the filters.

Jerry

On Wed, Aug 22, 2018 at 02:20 PM, Jerry Gaffke wrote:
I would not just randomly replace stuff.
You have dozens of parts to suspect.
And it worked when shipped.

Do you have 12v applied to the IRF510's when transmitting?
You should see 12v to ground on the tabs of the IRF510's when transmitting.
Could be as simple as not having 12v wired to the PA-PWR pin of that 3 pin uBitx connector as shown in the WireUp diagram on hfsignals.?

You should have a 50 ohm dummy load hooked up when testing the transmitter.
Output is typically 10 watts, but if you only use it for short periods at less than 50 percent of the time,
a 5 watt dummy load won't get too hot.

I doubt it will damage anything to test the transmitter without a dummy load, but it could.

Jerry
 

Do you see 12v on the tabs of the two IRF510's?
You don't have to key the transmitter to see this,
just have the receiver running.

When you key the transmitter, the IRF510 gates rise up from ground to turn things on.

What is the gate voltage at each IRF510 when you key the transmitter?

You can make these measurements with a DC voltmeter.
See 12v on the tabs (drans) of the IRF510.
Something like 4v on the gates, but only when transmitting
Jerry


On Wed, Aug 22, 2018 at 03:30 PM, Evan Clark (OSC) wrote:
orry if the last bit of the previous post was phrased oddly. I have connected the brown wire on the power in to the red one, so I am getting 12v to the finals. I now have 12v between pins 1 and 2 as well as 2 and 3. I'm still not seeing even a budge on the power meter, though.
 

Jerry, I'm still a little confused. When measuring the voltage on the gate for example, am I putting one end on the power input and one on the gate pin of the final? Sorry for such a noobish question. If that is the case, I'm reading 12 volts on the gate as well as the tabs.


On Wed, Aug 22, 2018 at 3:53 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
Do you see 12v on the tabs of the two IRF510's?
You don't have to key the transmitter to see this,
just have the receiver running.

When you key the transmitter, the IRF510 gates rise up from ground to turn things on.

What is the gate voltage at each IRF510 when you key the transmitter?

You can make these measurements with a DC voltmeter.
See 12v on the tabs (drans) of the IRF510.
Something like 4v on the gates, but only when transmitting
Jerry

On Wed, Aug 22, 2018 at 03:30 PM, Evan Clark (OSC) wrote:
orry if the last bit of the previous post was phrased oddly. I have connected the brown wire on the power in to the red one, so I am getting 12v to the finals. I now have 12v between pins 1 and 2 as well as 2 and 3. I'm still not seeing even a budge on the power meter, though.
 

Sorry for this, all, but just glimpsed this exchange:

Evan, have you ANY electrical knowledge at all? You seem to be too junior in Hamdom to realize that a Bitx of any sort requires that much background at least. But here goes:
Voltage is a relative measurement: difference between 2 points. If only one is quoted (Voltage On ...) The other point will be 0V - 'Ground'/'Earth', and that in modern parlace is the negative (-ve), and not always one particular color though usually black. This will apply to your meter leads - they will be black and red, the red being positive (+ve). Now try again. What do you measure?
 

Evan,

Not a stupid question.? All voltages are relative.??
In most cases, unless otherwise stated, relative to ground.
So black lead on ground, red lead on one of the gates.

Same goes for looking at the voltage on the IRF510 mounting tabs, that's relative to ground too.

If you see 12v on your meter both when looking at the IRF510 tabs and when looking at the IRF510 gates
relative to the +12 supply, that means they are probably both at 0 volts relative to ground.
And that's bad.

The IRF510 tabs should be 12v relative to ground whenever power is on.
Each gate should be about 4v above ground when the transmitter is keyed.
The gates can be? different, but should both be close to 4v.

Do not jump ahead and try adjusting the gate voltage without understanding the correct procedure.
Otherwise you almost certainly will blow the IRF510's due to excessive drain current.

Jerry


On Wed, Aug 22, 2018 at 04:29 PM, Evan Clark (OSC) wrote:
Jerry, I'm still a little confused. When measuring the voltage on the gate for example, am I putting one end on the power input and one on the gate pin of the final? Sorry for such a noobish question. If that is the case, I'm reading 12 volts on the gate as well as the tabs.
toggle quoted message. . .
 

I was thinking, Jerry, with Gate at 0V, Tab to either 0 or Gate would be 12V - *and* no RF out. :)
73 de ZL2DEX
 

Dexter, welcome to the asylum.
A data sheet for the IRF510 would come in handy so you can identify source,gate and drain pins.? As Jerry stated, the tab is also connected to the drain, although he choose an 'alternate' spelling.
(Jerry is indeed a team player, 'there is no I in dran')



Best of luck with the uBITX,
Gary
 

Ok, crap. I WAS measuring 12v at the tabs and 0v at the gates. BUT I think I bumped the inductor in front of the left final. Puff of smoke, a few visable sparks. Now measuring .84 volts either tab. Feeling quite disheartened.


On Wed, Aug 22, 2018 at 5:21 PM Dexter N Muir <dexy@...> wrote:
I was thinking, Jerry, with Gate at 0V, Tab to either 0 or Gate would be 12V - *and* no RF out. :)
73 de ZL2DEX

 

Drain voltage dropped to 10 mv, now slowly increasing at 50mv


On Wed, Aug 22, 2018 at 5:37 PM Evan Clark (OSC) <evanclarkie@...> wrote:
Ok, crap. I WAS measuring 12v at the tabs and 0v at the gates. BUT I think I bumped the inductor in front of the left final. Puff of smoke, a few visable sparks. Now measuring .84 volts either tab. Feeling quite disheartened.

On Wed, Aug 22, 2018 at 5:21 PM Dexter N Muir <dexy@...> wrote:
I was thinking, Jerry, with Gate at 0V, Tab to either 0 or Gate would be 12V - *and* no RF out. :)
73 de ZL2DEX

 

Oh dran!

Any idea where the sparks came from?
Any obvious scorch marks?

Sounds like you bumped L8.
Look at the schematic, L8 feeds 12v from PA-PWR into the left side IRF510.
I have no idea what "bumped" means, but if you shorted the wire that L8 is wound with to ground somehow,
that will burn out the trace between L8 and PA-PWR.
It's possible you burnt the coil, does the wire look discolored?
Just holding the red voltmeter probe against L8 while the black probe is on ground would not do this,
because very little current would flow through the voltmeter..

With the power supply disconnected entirely, short the PA-PWR wire to ground
then short each IRF510 tab to ground.? This is to make sure any caps are discharged.
Then set the DVM to the lowest ohms scale and measure ohms from PA-PWR?
to each IRF510 tab in turn.? Both tabs should be close to zero ohms to PA-PWR.
If one reads a lot more than zero ohms then either the coil (L8 or L9) or the traces
got burned.

A scorched trace could be easily repaired by soldering down a piece of wire.
I doubt you blew the IRF510's or any other semiconductors.

The gates should not be zero volts when you are transmitting, should be about 4 volts.
ff they were zero volts when transmitting, then that was your original problem
Otherwise the rig was working.


Might be a good idea to lug it off to a local ham club,
explain your adventure to some of the others attending
see if somebody there is curious enough about the uBitx?
to look it over with you and show you the ropes.

Jerry


On Wed, Aug 22, 2018 at 05:37 PM, Evan Clark (OSC) wrote:
Ok, crap. I WAS measuring 12v at the tabs and 0v at the gates. BUT I think I bumped the inductor in front of the left final. Puff of smoke, a few visable sparks. Now measuring .84 volts either tab. Feeling quite disheartened.

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