Axel,

Be careful, if you change the toroid to 5 turns the maximum allowed power becames 40-50 W.
You can frie the PIC controller with more than those 40-50 W.

73s CT4AJ

I have done this, both? to my QDXs Hi-LO and QMX.

Until now no problems.

73s CT4AJ

wrp should read qrp. Typo error
--
?

73, Barb

ATU100 wrp use modification:



--
?

73, Barb

On Wed, Jan 17, 2024 at 07:56 PM, Bruce Akhurst wrote:

No clue why you would do this (I have much experience of sockets getting problematic over time) -? but enjoy .

Hi

I am experimenting with QDXs (40-10, no LPFs - no BPFs, using magnetic loops, BARBs?FDT86256s vs)

so I consume a lot of BS170s

it is easier this way. (take out, test, change)

now with QMX :)?

73 de muhsin TA1MHS

?

I recognise, given what I've read elsewhere on the forum (particularly Hans' explanation of the power up sequence) and from reading the schematics, that if the 3.3V linear isn't working, then nothing will, so if the new PSUs work on the old board, then I conclude it must be working. But, I do admit to not having measured the actual node between IC101 and D103...

Actually, to make this clearer: when I put the new PSU modules onto the old main board, everything works, but new modules on new mainboard, no 3.3V rail on the pins along the top of the mainboard PCB, (or anywhere else).

No, the 3.3V regulator isn't coming up, at least one the older mainboard it does, but not this one. So PSU modules themselves are working.

¿ªÔÆÌåÓý

Hi Alison,

Oh dear Oh dear, you should always look closely!

I'm currently assembling the fourth ATU-100.
I ordered the first three about 2 years ago, they still required 5 W for control and,
according to the construction instructions, each had 10 secondary turns in the tandem
match transformer.

Then in July 2023 I ordered two more ATU-100 kits. They already have them
changed minimum power for tuning start: 1 watt

Unfortunately, I wound the Tandemmatch Transformer according to the old building
instructions with 10 turns each instead of 5 each.

Damn.

But it's also good that I noticed it.
So I'll change the transformer and everything should be fine.
Or can I save myself that?

On Thu, Jan 18, 2024 at 06:39 AM, Axel Kohlgrueber wrote:

Good morning,
Yes, you have to somehow push the required power into the ATU-100
so that it rattles properly and quickly.
A small transmitter with digital frequency setting would be ideal,
regardless of whether there is a 2 x 27m dipole or an end fed for 20m attached,
which sends the transmission signal to the ATU with 5 watts for 1-3 seconds.
I will probably change the ATU so that it gets by with around 1W.
In principle, it takes a bit of effort for me to pay €35 for a PICKit 3 programmer
when the ATU-100 kit only cost €28.
Can't you do the reprogramming without a programmer, e.g. with an Arduino uno,
or Raspberry 4, or PC?

Greetings everyone, DL5GT

I just see that the currently delivered ATU-100 with program version 3.2
has already been changed to 1 watt input power for tuning.

Good morning,
Yes, you have to somehow push the required power into the ATU-100
so that it rattles properly and quickly.
A small transmitter with digital frequency setting would be ideal,
regardless of whether there is a 2 x 27m dipole or an end fed for 20m attached,
which sends the transmission signal to the ATU with 5 watts for 1-3 seconds.
I will probably change the ATU so that it gets by with around 1W.
In principle, it takes a bit of effort for me to pay €35 for a PICKit 3 programmer
when the ATU-100 kit only cost €28.
Can't you do the reprogramming without a programmer, e.g. with an Arduino uno,
or Raspberry 4, or PC?

Greetings everyone, DL5GT

I think i didnt have my dummy load attached all the way.
Still lots of issues. I need to replace C508 and L503 at minimum. Any recommendations?

I have 2 ceramic disk capacitors in parallel replacing C508 currently. L503 is damaged but seems to work? Maybe?

Tx is half power on all bands.

80,60, and 40m are ok but rx is down 10db or so from before botched mod. 20 and 30m are terribly out of spec.

It's true. Last line of Rev 2 mod page.

¿ªÔÆÌåÓý

Can you tell if the 3V3 linear regulator is coming up? If it's not, then the MPU won't come up and turn on power hold.

I built a QMX low band in the summer with no issues. So, I bought a high band kit for Christmas and after building it, I see nothing. No bootloader, no start, nothing on the display. Comparing the two, on the second build, there is nothing at all on the 3.3V rail, it draws about 8.5mA while pressing the left encoder to power up, then nothing when I release the button. Unwisely maybe, I tried substituting all the individual boards from the new build into the earlier main board, and everything works there, so it must be some sort of fault on the new main board. I can't see anyone else with this issue on the forum, has anyone else seen this? Advice welcomed, at the moment it's sitting there useless!

George, M0HLP

-- 
Paul -- AI7JR

I have QDX high band and low band radios. Both assembled by QRP Labs. I noticed that the high band was not receiving many stations, and thought the band must be closing - over a month or so. Then I received the low band from Hans and tried it on 20 meters, and Wow, was there a lot of traffic. I started comparing the two on 20 meters using the same power supply (10 volts into 12 volt radios) and the same antenna.
Below are screen shots of the spectrum on JTDX for both radios, the low band first, then the high band.


I next ran the RF Filter Sweeps for both radios and took screen shots, low band first, then high band

Both are running on v1.10.
This is the high band's filter sweep on 17M:

Where should I start looking to fix this?
Thanks,
Don KD5NRO

Per,

I have exactly the same problem with my Rev 1 QMX build running firmware 014. I had good results running barefoot on Ft8 and thought I would try hooking up my QRP Labs 50W amp. Much to my surprise, I have a constant 5V on the ring of the PTT in receive or transmit. I too hope the next firmware release will fix this.

73,

Pete, KH6GK

Found the problem!

The Source leg to Q507 (an AOD403 MOSFET key shaper circuit) had not been soldered to the board during factory install of the SMD components.
I hope this will not be an issue for other boards out there.?
I enjoyed the troubleshooting process, despite the hassle. I determined the issue must be in the initial Tx stages and started looking there.
Thanks for all the suggestions - it really got me thinking and looking.

73 Larry VE7EA

¿ªÔÆÌåÓý

Have you looked at the sweeps to see how they look?