Re: QCX 50W T1&T2

John Pagett G4YTJ

Notwithstanding Hans’ comment about using superglue, when I tried it in the past it set so quickly as the parts were placed together that it was impossible to get a snug fit because the set glue was too thick.

I eventually used silicone rubber, which had the advantage that with pressure the gap can be squeezed right down.

Admittedly this was with very flat faces of two transformer halves, but it worked very well on what was a commercial product.

The two parts stayed together well once the silicone had set.


Re: QCX 50W T1&T2

Hans Summers

Hello Claus

The best and easiest thing to do is to super-glue the two halves together and proceed regardless. The electrons don't care.

73 Hans G0UPL

Re: QCX+ CAT interface ... USB converter


Basic CAT control working well for Ham Radio Deluxe with this cable straight out of the box from Amazon UK:

Re: QCX 50W T1&T2

Timothy Fidler

someone else from Europe had hte same problem and after some dimensions from him (I had some from Hans on another issue - same amp ) I came to the conclusion that two off  type T61-80s stacked would be the best approximation for the material and dimensions of T2.  
Type 43 is darker and glossier than type 61 material which is a dull grey colour.  Of course I have no descriptions of what you have. 
Long and short of it was he did that and he got 10 W out at 12 V and was very happy.  This is a non linear amp and you'd expect around 14-15 W out at 14V and quite a bit less at 12 V (his 12V might have been 12.5V for all I know).
The only place you can get these cores reliably in small qty is  DIz at Kits and Parts in the US. 
There is RF and Microwave in  Italia who charge a fair bit more but they have a minimum charge I believe . Have a look at the pricing and esp DELIVERY COST and TIME and work out what you are best doing. 
Don't damage those long cores (coax cores) for the main RF transformer as they are unobtainium except from Hans. Tests done for me in the UK indicate they are either 4C65 Nxp material or US (Fairrite) type -61 material - there is no practical difference between them .  NB those tests were ONLY for the COax type cores. 
Onwards and Upwards - 
if you drill very carefully or otherwise  create some pads for three standoffs in the area where the LPF is on the current  PCB there is the option to create a switched  second LPF in high rise style using Isolated pad construction on  a bit of PCB you supply .  Then you can have a dual 40 and 30 mtr "50 W " amp with frequency chosen by flicking a switch. I'd suggest you use American Zettler 12V relays from Far circuits (Fred ) in Chicago USA  if you are going to do that as these are known good to transport 40W of RF power.  Make sure you know the dimensions of them in planning any board change. I'd lie them on their sides to keep the delta board height down.

Re: 10m QCX L4 and T1 windings #qcx

Akira Murayama

Oh, excuse me, Dick. I missed that information. Yes, 3 turns for each of the three small windings on T1.

Best wishes for your building of the new QCX kit!
73 de Aki, JR1XKU

Re: 10m QCX L4 and T1 windings #qcx

Dick PA3CW

Many thanks Aki! I will keep you posted on the progress. Did you keep the other windings to 3 on T1?
All the best, Dick PA3CW

Re: vfo/signal generator

Mont Pierce KM6WT

On Tue, Sep 21, 2021 at 10:26 AM, Syd wrote:
Checking on the LCD pins 2 & 15 there is 5Vdc and pin 3 shows the LCD brightness control Vdc and is OK (at lowest voltage I do see faint, barely visible display boxes),
Are you seeing blocks on both lines or just the top line?


Re: UProc reset

Mont Pierce KM6WT

On Tue, Sep 21, 2021 at 08:50 PM, Syd wrote:
Will installing the R3 resistor replace the jumper shown on the schematic so I can reset the UProc?
Yes, you can install either the jumper or a 100K resistor at R3.

This is mainly used if you want to use the ISP port to update the ATmega328p firmware in place.

You could install a push button between the Gnd pin and Res pin at the ISP header.


Re: QCX-Mini Alignment Issues


But to answer that question more precisely, I suggest you trigger on the main injected signal and look at the traces on at at time (assuming you don't have a third probe) using the expanded trace method and increased injection voltage I proposed. There definitely is a phase shift when things go wrong, so syncing to the incoming clock and comparing good/bad traces will show the offender.
Julian, N4JO.

Re: QCX-Mini Alignment Issues


On Tue, Sep 21, 2021 at 12:42 PM, @egads wrote:

sigh. Since the stages aren't really independent of each other, how do we go about teasing out which stage has the problem?

 Yeah, that's the big question, innit?
Comparing those three traces, it is the purple (Q) that changes the most, in amplitude and shape. The phase shift certainly does increase, which is, of course, consistent with the increase in noise.

You have a soldering iron: when the unit is cold and working correctly, could you try heating IC6 and IC7 independently to see if you can trigger something with a bit of thermal stress? Don't cook them, obviously, but we know that putting it in the case seems to trigger the bad behavior more readily, right ?

I'd be inclined to replace IC6, then IC7, as the most likely suspects. Just to offer one more time, I can do that for you, if you don't have SMT rework resources. 
Julian, N4JO.

Re: nylon washers

Timothy Fidler

you can make ersatz nylon washers out of used   2 litre  flat sided drink container PE material as sold in Oz and Nz. You can use a hole punch for about a 4mm hole size and if you want it bigger a soldering iron will open it out.  It is very hard to drill this material if you want smaller diameter  holes but if you nail it down to a bit of wood with tacks you can.  such washers are going to be square but for electrical insulation and not beauty purposes  that is fine.  PS. Very cheap effective  washers  too.


Re: QCX Mini - Would not respond to any button presses


Fascinating! It's late now, but I'll certainly check that out in the morning: I've got older code in my classics, and 1.07a in a Mini.....
Julian, N4JO.

QCX 50W T1&T2

Claus, OE6CLD

Hi all,

I bought a QCX 50W together with a QCX 40m about 3 years ago. Build the QCX but not the amplifier (never had the time). Meanwhile I relocated 2 times and recently build a QCX Mini 30m. Now I wanted to start with the amplifier and found out that one of the toroids (T1/T2 ) has been broken I to parts.

Can someone help me please. What kind of toroids do I need to buy? Any help would be appreciated.


UProc reset


On page 7 of the assembly manual for the VFO/Signal Generator one can install R3 (100k) resistor or a jumper wire. I want to reset the UProc, so I assume the R3 option, not the jumper option, has to be installed.  There is a UProc reset pin in the diagram in the schematic that I am assuming has to be set to gnd to reset the UProc. The schematic shows a jumper wire to 5Vdc at the reset pin which means a 100k resistor would be useless on  this pin. Will installing the R3 resistor replace the jumper shown on the schematic so I can reset the UProc? I just want to be able to reset the UProc.

Re: QCX Mini CAT control for CW with N1MM

Bruce K1FFX

In addition to its online docs, another N1MM resource is

- Bruce K1FFX

Re: QCX Mini CAT control for CW with N1MM

Jim McCusker (K3YO)


i can confirm that the KY CAT commands work perfectly.  I used FLRig to confirm it works.  I’m just hoping to figure out how to configure N1MM to use KY commands.  I’m pretty sure it’llwork, just need to learn more about N1MM.


Re: 10m QCX L4 and T1 windings #qcx

Akira Murayama

Hi Dick,

For my 10m QCX+, I used following values:
T1: 18 turns
L4: 7 turns

For L4, I tried 6 turns to 12 turns, at 1 turn increment, and the set of BS170s that came to me seemed to like 7 turns best.
After adjustment of L1-L3 as per Hans' tune-up video, power output is about 5W into 50 ohm dummy load at 13.8V input (without the protection diode, D3), comparable with the units for 80m - 20m bands.

I hope you will have good results, also, soon.

73 de Aki, JR1XKU

Re: nylon washers

Mont Pierce KM6WT

On Tue, Sep 21, 2021 at 09:04 AM, Syd wrote:
In the signal generator kit and others, Hans uses nylon spacers and nuts and screws. I want to go on Ebay and buy a few nylon washers that will fit the size of nylon bolts that Hans is using in his kits.
I liked Hans spacers too, and wanted more of the same that would work with QL kits and other projects.

Found this set on Amazon (click here).

They are black, instead of white like QL kits.  But totally compatible and interchangeable.  :)  :)


10m QCX L4 and T1 windings #qcx

Dick PA3CW

Hi QRP labs community! I have a 17m QCX with 10m lpf. I am planning a 10m version as basis for a tiny 2m transverter ( from  Who has experience with determining the number of windings for L4 and T1 for 10m?
Many thanks,
Dick PA3CW

Re: QCX-Mini Alignment Issues

R. Tyson

Looks O.K on that photo. The first photo I looked at gave the impression that the solder might not have taken to the wire of the lead. But, as I said, the other photos looked O.K. Guess it was just the angle and lighting that made it look a bit suspicious.

Reg             G4NFR