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Remember that you have to enable PTT in the band configuration menu.? You can enable either positive or negative PTT mode.? Without this configuration, no PTT will happen.

Mark
KD0QYN

Dear all, I am new? to the QCX. I bought a rig with version 1.04. How can I get the latest firmware?
I am also struggeling to pick up the output power to more than 2 watts. Is there any video explaining how to tune? the 3 output toroids ??
Many thanks for your help!
Leon

Just re-reading your very useful thoughts which I agree with
?.. ?as I said. Leaving it for now as I don’t think it matters if ‘another’ close nearby ground is or isn’t there as it’s clean and stable and the case is extremely RF and DC grounded close by already so
very limited scope for any loop, offset
or diode effects etc . ? I learned a while ago that the best grounding solution in RF cabinets is the one that works not the one some complicated theory might favour ?

You did mention the BS170s (2 push pull, one thermally linked for bias) running cool. ?I imagine they are outputting 0.5W or so at 10W out which isn’t so bad at first sight, maybe dissipating a bit more than 0.5W /2 each ?but they are closely attached to a shared heatsink and board that are already regularly 40C and can get a lot higher (due to the final IRF510 pair’s dissipation not their own )

Probably with a 50C main heatsink and if Tjc overall is something around 50C/W they have Junctions at 60-80C and sharing the same main heatsink at 50C was still a better bet for them than another smaller heatsink working in the available in the ‘50C airspace’ ?for limiting that ?

I think they can easily stand that but also mused that the ‘Bias’ FET adjustment process’ ?is therefore mostly subject to the main heatsink temperature by then although it’s still a valid approach as equally so are the actual driver transistors?

On 04/06/2024 07:22, Martin DK3UW via groups.io wrote:

do you mean with that setup transmitting is no more possible ?

Martin,

IQ mode is for RX only.

There is no transmit.

Hans has said that one day he can add TX but that could be a long time.

73 Alan G4ZFQ

Hi Alan,

sounds complicated at first sight for me. Receive only ? I do not want to see the waterfall, when transmitting or do you mean with that setup transmitting is no more possible ?

Martin
DK3UW

The problem with RF switching is that the transmitter/transceiver is always exposed to an junpredictable load until the relay in the amp has operated. My FT817 PA lasted a matter of seconds until it blew while driving a Yaesu FL110 amp in RF switching mode. It's well worth getting switching with the PTT sorted out. You may get away with it, you may not...I didn't!

If you're thinking of using the amp with a QCX mini or the like, note that the PTT switching condition is +12v for transmit, I.e not suitable for your amp, you'll have to include some sort of circuit to invert the PTT signal.

73 Steve

Hi All,?

Many thanks for the advice.
Ed, I wound mine with both starting from the bottom. The linked diagram is the same as a QRPGuys on I found. As said on this thread they are the same.
My comment of over-thinking has been confirmed more than once. ;-)) BUT there is a physical difference between "our" windings. Considering just one end of the bino mine both wind up the side and on yours one winds bottom up and one top down!
Does it make a difference?? I'll find out this week when I finally clean up some poor soldering on some of the coils and if? I dare connect some power.

73
--
Phill EA5JHA

Many thanks for the reply. I may stick to RF keying for now.?

And yes, thank you. I've been reading up on things like not overdriving the TH-P. I'll be careful!

USE BS 170? Connect? Source to pin? 6? Drain to? 8? and put? a pull down of? ?100 ohms between gate? and? the? ?source . that's it? no current limiting required and there's? 100 % isolation between? the? activation volts and the? wetting voltage from the? ?Hipower excetp of course the share a common? zero volts line? . NO relay with this method? either.? BS170 will take? 60 V? Drain to? Gate which is far in excess of the? amp's supply voltage.?

?

Beware.? The? Tokyo? ?irreplaceable? ?Hi power amps generally have NO over drive protection and can be burned out in this way? ?.? The? outputs generally have? SWR and overload protection.??

Hi,

Yes, the brightness of the backlight changes.

Sepehr N6IRN

Hi Sepehr,

Is there any change in the display if you adjust R305 trimmer pot on the display board?

Ed ?KN6NZW

It is the most common problem I see here. The grounds are easy to cold solder. After that, you have to trace voltage to the screen and ground.?
--
Colin - K6JTH?

I have checked the cutoff lids. There is continuity on both sides of every pin. Will check again just in case.

Thanks,

Sepehr N6IRN

Jay

I am very fond of these guys:



they have a wide array of products, many of which are not 100% plug-n-play, and that can appeal to the DIY'ers often found building kit rigs.

They're quite ham-friendly. I have no business relationship with them, just a long term happy customer.

Steve KZ1X

HI Ludwig,

-Will lower supply voltage to 8 v for further testing.

- I previously measured 9.8 k ohms across BS170 drain to source.? Will recheck that measurement.

- Will do the temperature test as you describe and report.? The MFJ p/s reads about zero indicated
? but the scale is 0-32 amp.? Have not worked out an arrangement yet to use DMM for more precise measurement.
- i have an oscilloscope.

73, Charles

I re-ordered new power boards and received them today.

I am happy to say, after installing the new board, my QMX powered up and I was able to do the FW install.

Once it re-started I was able to choose my bands and the CW speed. I have not been able to test it any more than that but I will fire it back up this weekend and see what I can hear. But the good news is my QMX powers up and appears to be working.

The cutoff leads can be hard to solder for the screen. Check them carefully.?
--
Colin - K6JTH?

Hello,

Just finished building the QMX and loaded the firmware. The screen lights up, but there is no text. I have tried both reloading the firmware and adjusting the contrast using the capacitor, and neither solved the issue. Does anyone have any suggestions as to how to fix this, or what might be causing the issue?

Thanks,

Sepehr N6IRN