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I was adjusting rv2 and rv3 , tried to measure voltage on gate pin then ubitx relay starts clicking and irf txing.

How do i safely measure gate voltage on board? Used multimeter probe on gate and common on earth of supply.

Think ive goosed it!

73's
Alan
MM0WXT

Alan,

The circuit may oscillate if you put multimeter probe on certain pins.

No need to measure gate voltage. Only the final current.

I recommend to my friends DO NOT adjust bias, check final current it if not Txing.

Set bias ONLY IF you replace the finals. The board comes set from HFSignals.

Raj

I had it all up and running on receive working great for a week. I then got ahead of myself, over tiredd, and plunged a screwdriver in and messed with RV2&3. Still ok on receive.

Today I twiddled with Rv1, following something I had read earlier. Probably wrongly...grrrrrr... :-(

I then plug in a a cw key, for it to start this fault with the raduino flashing like a bordelo sign. I then notice the 4.7k snapped away from audio connector pin.

I have:
1. Stripped it all out of case
2. replaced 4.7k with new

rv2&1 are fully clockwise

raduino still flashing on and off when plugged into ubitx

Not flashing and all good when plugged into usb and pc

No idea what I have done!

What is the safest position to turn rv1,2,3 to ? My instinct is raduino regulator blown due to resistor malfunction? I am a complete newbie at this. please be patient...

Many thanks

Alan?

Alan,

If your are receiving OK and tuning ok then the Raduino is working!

Raj

At 20/02/2018, you wrote:

Hi Raj and thank you! It was all ok on receive up until today. Once the raduino is plugged into ubitx it goes haywire and just goes on and of so can't even get as far as receive.

It seems tied in more with the broken 4.7k which happened today it all went nuts after that. As well as my prior sillyness :-/

Can you buy spare raduinos? or how do I go about fixing a fault relating to 4.7k malfunction?

Thank you

Alan

Good advice.? ?Yes, check the power supply voltage into the board.

But I would guess that after twiddling RV2 and RV3, the IRF510's are sucking too much current on transmit,
and so bring your power supply to its knees.?

I would suggest that you remove power from the IRF510 drains by not supplying 12v to the PA-PWR pin?
(the middle pin of the three pin power connector).?
Leave it unconnected till you have the receiver working again.
Also turn RV2 and RV3 fully clockwise for minimum (zero) drain current.? (Backwards of most knobs in this world)
RV1 should probably be about mid-range, determines how much drive the final transmit amplifier gets.


Find K1, which is the relay nearest the 3 pin P1 power connector near the left back corner of the board.
Find K1 pin 1, has the square pad on the bottom of the board, furthest from the board corner,
this is the TX 12v power rail, it will only have 12v when the rig is trying to transmit.
So your first debug step is to verify that K1-1 is zero volts when you power up the rig,
if it is 12v then the rig thinks it is transmitting, perhaps because of an issue with that 4.7k resistor.

Hopefully, the rig is not receiving.
Current draw should be around 150ma into the rig from the 12v supply.

Now re-attach the middle pin of P1 to 12v, so we are now supplying power to the IRF510 drains,
but monitor the current into that pin from the power supply using a DVM set to read up to at least 3 Amps
(probably the 10 Amp range).? You are measuring current, so the meter is in-line, between the power supply
and pin 2 of that power connector.? Attach a 50 ohm dummy load to the antenna port.? Turn the rig on,
should be receiving.? Press PTT, you will hear the relays click, and that TX rail at K1 pin 1 is now at 12v.?
Current on the meter should be zero (I assume RV2 and RV3 are still fully clockwise).?
Slowly slowlly turn up RV1 till the meter reads 100ma.? Then slowly turn up RV2 till the meter reads 200 ma.?
The transition to zero current to several amps is quite sudden, toward the end of travel for RV1 and RV2,
and running with several amps of drain current like that can quickly blow the IRF510's.
Check that the IR510 heatsinks are not getting hot, should never be uncomfortable to hold your finger on them.

If you were able to adjust the drain current at each IRF510 to 100ma (200ma total) in the above step
then you have not yet fried the IRF510's.? Otherwise, it may be time to place an order for some IRF510's.

In addition to frying the IRF510's, you could also have fried L8 and L9, and the traces to them.
You can check for this by transmitting with no audio into the mike, and using your voltmeter from drain
(the top pin in the schematic) to ground on each of the IRF510's, should see 12v dc there if L8,L9 are ok.

At this point the rig should be working, and when speaking into the mike there should be power into
the dummy load.? You can now adjust RV1, increasing it by turning counter-clockwise to where there is
a bit of distortion in the transmitted audio as reported in an on-the-air test when speaking in normal voice
into the mike, then back it off somewhat from there.

Moral of the story:? Don't fiddle with RV1, RV2 and/or RV3 unless you have good reason.

Jerry, KE7ER

Said:? Hopefully, the rig is not receiving.
Should read:? ?, Hopefully, the rig is now receiving.

I will rattle through your kindly provided steps once I have a sleep. tiredness and absent mindedness got me into this pickle in the first place.

On that note a VERY BIG THANK YOU. And I will get back to you guys sokn.

73's & NN
Alan

As I remember my uBitx with everything wired correctly and 4.7K omitted the board
would go didahdiah indefinitely.

One board came with a defective USB socket which I fixed. After a 10 days stint at
my farm and back the board was refusing to program but running fine with my old
experimental sketch. A reset completely bricked it. I desoldered the Nano from the
nano side and cleaned the (raduino) pins well. I then plugged in a new nano but did not solder
it as it a tight fit. Uploaded the sketch into it and glad to say all is well with it now.

The spare nano I used was without pins soldered. Something like this:




Raj

ok wonderful people...here is what I have done.

1. I hooked up the raduino to pc and checked volts, all good.
2. Disconnected? pa power turned rv1,2,3 all fully clockwise (towards metal dot on pot?), cut of cw mic connector snd bridged green and blue with 4.7k resistor.


Zero volts on KT1 pad and 250ma draw on receive. No raduino going mad. So as sugested PA POWER.
3. Setup ammeter to measure current. Hoked up pa. Current 170, smoke coming i think from first?
Irf510. It was hot, rightside irf520 cold. Rig only on 2-3 secs.

Desoldered irf 520, replaced with new.

Still to switch on......eeeek!

All my pots are turned fully rightwards (clockwise)

Todo:hookup ammeter and power with thicker jumpers(melty on switchon!),

May God bless all who sail in Her....:-)

Thanks

Alan

A few more details here please:

Is the receiver working properly now?
When you measured "Current 170. Smoke coming", is that 170mA and what current were you measuring and were you pressing PTT?

It should take several Amps into PA-PWR for an IR510 to smoke like that and few of us have 170 Amp power supplies.
So my best guess is that you measured 170ma into the main board and didn't include PA-PWR in that measurement.

And would also guess that the reason for your failure is mindless twiddling of RV2, RV3.
These should be set properly at hfsignals and most of us will likely never have reason to mess with them.

Jerry, KE7ER

Don't get me wrong, I applaud your willingness to reach in and play with your uBitx.
That's what these rigs are all about.
Just taking the opportunity to let others in the forum know that twiddling RV2 and RV3?
can have negative consequences.

Jerry. I was reading an article I mistook RV1 for RV2, got into a panic and before I knew it I was in the "Keeck" as we say in Scotland :-)

Tiredness, panic and daftness. I will now go and stick the Conical Hat on , and go stand in a corner.....

I did not press PTT, I had Power direct into rf power and ammeter in series with 12v power line, soon as 12v gets plugged in smokey...Fairly sure IRF, But could have been the entire capacitor bank at the Low pass filters...HOPE NOT!!!!!

Had an IRF510 , so put it in.

Not fired her up yet.
Should I have ammeter across both 12v and pa power?

Thanks

Alan

Should I be measuring pa current or both? E.g. both wires from psu to black probe and 2 wires running of red probe to each input?

Doesn't matter if psu connects to ammeter black or red,
will likely read with a minus sign if you put the black ammeter probe on the PSU.

I suggest you measure PA current separately, since I think you already have a handle on the main board supply current..
Should see 0 amps with both RV2 and RV3 fully clockwise (minimum) with ptt pressed.
Then you slowly slowly turn RV2 up for 100ma, and then RV3 up for an additional 100ma.

Hi Jerry and thanks again,appreciated.

Just taking this now in little steps. I will get back to you.

Thanks

Alan

When replacing that IRF510, I'd just clip the old one out leaving stubs 1/8 inch long,
and then solder the new one onto those stubs.
Avoids ripping up the board when removing the old pins.?
And very easy to replace the next time.? ?;-)

Hi Jerry.
No effect on amps moving RV1.
100ma each on adjustment of RV1&2 whilst pressing PTT on mic
PA,Brown, supply 200 ma on PTT
12v,red, rail 250 in receive 550ma tx

A loud hallllow produces no change in current. Dont have swr so no idea of output to load.

But receive working and things are a beginning to click.

Thanks

Alan



Should i be seeing circa 1.8 amps on voice modulation and PTT? 13.8v psu