Date   

Re: QCX+ RF Power #qcx

Dave VE3GSO
 

I am reminded of a time a friend retuned a 25W 2m transmitter and eventually got almost 60W output, as measured on a Bird Wattmeter. Unfortunately the fundamental was still only 25W, with the remaining power contained in spurs and harmonics that earned the wrath of the regulators.

So all I am saying is have a way to check for second and particularly third harmonic levels when you start raising the cut off frequency of the low pass filter.

Yes, it is entirely possible that the inductors are higher value than the design goal. And reducing turns to achieve the design value is a very good thing. Just be careful out there!

Dave


On Sep 12, 2020, at 18:53, Arv Evans <arvid.evans@...> wrote:


Al

My idea was to determine the tuning range of compressing versus expanding windings.  Once known this could predict whether you need to add or remove turns or just adjust turn spacing.

Adjustment of turn spacing is more about distributed capacitance than about changing the inductance, so making a predication formula or software tool may be a bit difficult.

Arv
_-_

On Sat, Sep 12, 2020, 4:05 PM Al Sines <sasines@...> wrote:
Arv,

Not sure if this is exactly what you are thinking but so far with my new QCX PLUS 20 meter these are the RF output results:

Input voltage 14.5 
Reverse polarity diode is installed

After winding coils L1, L2 & L3 as specified in the manual:

1 watt out measured on bird wattmeter 

After spreading the windings on all three coils as much as possible:

3 watts out on the bird wattmeter 

After removing one turn each from L1, L2 & L3:

4.5 watts out on the bird wattmeter. 

I wound my coils very tight and close together at the start. 

I am thinking about removing one more turn each from L1, L2 & L3 to see the effect on the RF output.

In a way I am hesitant to do so cause it all works so well but sometimes my OCD makes me want to get the whole 5 watts out at about 13.2 volts (13.2 is the voltage of my bioenno when charged)


What say you?  Thanks

Alan, W3AL




On Sep 12, 2020, at 13:14, Arv Evans <arvid.evans@...> wrote:


Might be interesting and informative if some ambitious person 
would do some tests and make chart or on-line calculator that 
shows the effect (tuning range) of spreading and compressing 
turns on a toroid.  This could possibly show ends of tuning ranges 
and indicate at which point one would need to add or subtract 
a turn versus where compressing or expanding turns could be 
effective.

Arv
_._


On Sat, Sep 12, 2020 at 11:09 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
Try one turn from L4 and spreading the turns for best output.

Allison
--------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Missing QCX L4, opinion-question

Phil N6WKZ
 

Allison,

What purpose does L4 serve in the QCX? (Keep RF from going into the power supply??)

Do you know what frequency that L4 operates? The T37-2 has a lower limit.

Phil

On 9/12/2020 6:40 PM, ajparent1/KB1GMX wrote:
Yes.  It will take a lot more turns.  IF the wire overlaps because the
needed turns do not fit the calculation will be off.

For 1.5uh on t37-2 the calculators say 19.4 turns, its going to be 19 or 20 as is
not such things as  .4 turns with toroids.

For the same  1.5uh on T37-6 it will take 22.4 turns so use 22.  

The distributed capacitance may be a factor [usually at higher frequencies]
but the general idea applies.

USe Diz's calculator to play.   http://toroids.info/T37-6.php

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Missing QCX L4, opinion-question

ajparent1/KB1GMX
 

Yes.  It will take a lot more turns.  IF the wire overlaps because the
needed turns do not fit the calculation will be off.

For 1.5uh on t37-2 the calculators say 19.4 turns, its going to be 19 or 20 as is
not such things as  .4 turns with toroids.

For the same  1.5uh on T37-6 it will take 22.4 turns so use 22.  

The distributed capacitance may be a factor [usually at higher frequencies]
but the general idea applies.

USe Diz's calculator to play.   http://toroids.info/T37-6.php

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Compressing or expanding turns on a toroid.

ajparent1/KB1GMX
 

There is a interaction with turns and capacitance and it shows up when measuring Q.

The assumption is the mu of a toroid is higher than it really is.  So if you concentrate
the winding your also concentrating flux and therefore the inductance. 

Te easy test is to measure at a much lower frequency where the capacitance small
as it is is less significant as compared to the inductance.

The problem with that is mu of most magnetic materials is also related to many factors
including frequency.  

So the calculation used most often is an approximation.  The error is not linear.

Just like 468/f (142.64M/F) is rarely the exact length of a dipole.  They do not take into
account height above ground or diameter of the conductor or if there is dielectric to
name a few factors.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Compressing or expanding turns on a toroid.

Timothy Fidler
 

Perhaps my workings are a parallel of what was in the Radcom magazine article . can't comment on that.  I came to them independently based on reading between the lines of the standard text  Buck and Hayt .

....and guess  what you little possums.. someone on this very site, an Italian no less , sent me that as an Ebook for nix cost .  Ya  don't look a gift horse in the mouth..nor talk about it too much if you have any brains..  :-)) 


Missing QCX L4, opinion-question

Phil N6WKZ
 

Do you think that a T37-6 could be used in place of a T37-2 for use at L4 ? If I match the correct inductance?

73 Phil N6WKZ


Re: BPF 80m

DL2ARL
 

 geoff M0ORE

I humbly excuse my english as not being breed at Oxford.
As for the insertion loss being negative, I know a word that fits  marvelously: in german they say to it Korinthenkacker.
Your fine remark has helped a lot to  clear the problem described above, thank you.
Enjoy your digestion.

Yours Razvan DL2ARL


Re: QCX+ RF Power #qcx

Arv Evans <arvid.evans@...>
 

Al

My idea was to determine the tuning range of compressing versus expanding windings.  Once known this could predict whether you need to add or remove turns or just adjust turn spacing.

Adjustment of turn spacing is more about distributed capacitance than about changing the inductance, so making a predication formula or software tool may be a bit difficult.

Arv
_-_

On Sat, Sep 12, 2020, 4:05 PM Al Sines <sasines@...> wrote:
Arv,

Not sure if this is exactly what you are thinking but so far with my new QCX PLUS 20 meter these are the RF output results:

Input voltage 14.5 
Reverse polarity diode is installed

After winding coils L1, L2 & L3 as specified in the manual:

1 watt out measured on bird wattmeter 

After spreading the windings on all three coils as much as possible:

3 watts out on the bird wattmeter 

After removing one turn each from L1, L2 & L3:

4.5 watts out on the bird wattmeter. 

I wound my coils very tight and close together at the start. 

I am thinking about removing one more turn each from L1, L2 & L3 to see the effect on the RF output.

In a way I am hesitant to do so cause it all works so well but sometimes my OCD makes me want to get the whole 5 watts out at about 13.2 volts (13.2 is the voltage of my bioenno when charged)


What say you?  Thanks

Alan, W3AL




On Sep 12, 2020, at 13:14, Arv Evans <arvid.evans@...> wrote:


Might be interesting and informative if some ambitious person 
would do some tests and make chart or on-line calculator that 
shows the effect (tuning range) of spreading and compressing 
turns on a toroid.  This could possibly show ends of tuning ranges 
and indicate at which point one would need to add or subtract 
a turn versus where compressing or expanding turns could be 
effective.

Arv
_._


On Sat, Sep 12, 2020 at 11:09 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
Try one turn from L4 and spreading the turns for best output.

Allison
--------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Compressing or expanding turns on a toroid.

Curt wb8yyy
 

Yes nice explanation that physical arrangement of the coil adjusts inductance.

One can measure inductance by resonating with a capacitor, measuring frequency,  and calculating inductance from that. Here in US the njqrp once offered a little kit that measured inductance and capacitance, in era before cheap lcd. Read them out in morse. I don't know what's out there now, but an LC meter would be a nifty offering,  yeah take advantage of a market here too focused on their coils.

73 curt


Re: QCX+ T1 Toroid Wire Length? #20m #qcx+ #20m #toroid

Bob Ballard
 

FWIW - From a new guy who doesn’t have a clue about the details of the electronics –

 

My 20M QCX+ cranked up right away after I built it but it only output 3.1 Watts.  After reading Hans’ commentary regarding what he did to correct the issue on a 30M QCX+, I removed one turn from L3 and squished the turns closer together on L1 and L2.  My result was 4.8 Watts so I’m leaving mine where it is.

 

73,

Bob – KG5SQJ

 

From: QRPLabs@groups.io <QRPLabs@groups.io> On Behalf Of Al Holt
Sent: Saturday, September 12, 2020 7:09 AM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] QCX+ T1 Toroid Wire Length? #20m #qcx+ #toroid

 

I've been using "mini Ring Core Calculator" (mRCC) software by DL5SWB for toroid winding info. It also has the reverse, turns-to-inductance, mode which then can be plugged into its main calculator to get wire length.

For a 20 meter T1 with 39 turns (30 plus 3-3-3), mRCC reports that as 7.453 uH on a T50-2 core and the length will be 58 cm. I'm going to stick with metric to make adding it all up  easier.

But you need to add the additional loop lengths and the start and end lengths. Hans says have about 3cm for the start length.

For the loops figure between 10 to 15 cm (5-7.5 cm out and back) for each loop. So, worst case here, an extra 45 cm for the three loops. 

That gives us: 5 + 58 + 45 + 5 =  113 cm (~44.5 inches). You'll probably wind up with a few extra cm's, but you bought that spool, right? Always a good idea to have the extra wire!

That's the method I use. PLEASE, check the math and download the software! An extra set of eyes and grey matter always helps!!

Good luck!
 
--Al
WD4AH


Re: Compressing or expanding turns on a toroid.

geoff M0ORE
 

Inductance is a difficult parameter to measure accurately. A coil has all three components which affect the measurement. L, C and R. The formula only caters for the number of turns and the C and R components are in the lap of the Gods. Hence we can alter the perceived inductance by compressing or spreading the turns.

G3BIK  wrote a very good explanation of coil construction in the RSGB magazine RadCom Dec 1994 if anyone wants to read up on it.

On 12/09/2020 21:49, Alan G4ZFQ wrote:
My  understanding is that all one changes by compressing and expanding the turns is that one changes the distributed capacitance and not the inductance. Looking at the formula for the inductance of a toroid I see inductance being dependent on the number of turns squared, the cross

As a retired motor technician maybe I'm not qualified to wonder if it is possible to measure inductance? Do we just measure the apparent inductance?
All inductors must have distributed capacitance, does the formula take that into account? Certainly squeezing/stretching the coil must alter the capacitance?

73 Alan G4ZFQ




Re: QCX+ RF Power #qcx

Al Sines
 

Arv,

Not sure if this is exactly what you are thinking but so far with my new QCX PLUS 20 meter these are the RF output results:

Input voltage 14.5 
Reverse polarity diode is installed

After winding coils L1, L2 & L3 as specified in the manual:

1 watt out measured on bird wattmeter 

After spreading the windings on all three coils as much as possible:

3 watts out on the bird wattmeter 

After removing one turn each from L1, L2 & L3:

4.5 watts out on the bird wattmeter. 

I wound my coils very tight and close together at the start. 

I am thinking about removing one more turn each from L1, L2 & L3 to see the effect on the RF output.

In a way I am hesitant to do so cause it all works so well but sometimes my OCD makes me want to get the whole 5 watts out at about 13.2 volts (13.2 is the voltage of my bioenno when charged)


What say you?  Thanks

Alan, W3AL




On Sep 12, 2020, at 13:14, Arv Evans <arvid.evans@...> wrote:


Might be interesting and informative if some ambitious person 
would do some tests and make chart or on-line calculator that 
shows the effect (tuning range) of spreading and compressing 
turns on a toroid.  This could possibly show ends of tuning ranges 
and indicate at which point one would need to add or subtract 
a turn versus where compressing or expanding turns could be 
effective.

Arv
_._


On Sat, Sep 12, 2020 at 11:09 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
Try one turn from L4 and spreading the turns for best output.

Allison
--------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: #40m #40m

N3MNT
 

You will need a USB to serial TTL interface.  I am using this one and it works fine  https://www.amazon.com/gp/product/B07BBPX8B8/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1   


Re: QCX-mini update

Hans Summers
 

Hello Janez

I have no plans to offer the QCX-mini both with and without the SMD parts pre-soldered. To do would increase the complexity and cost of production, which does not seem worthwhile for what I believe would be a rather small minority. 

Furthermore it seems to me highly likely that a significant proportion of constructors, not including you Janez, would over-estimate their capability to deal with 0603 SMD components and this would inevitably lead to a larger support burden on me. I have enough support headache as it is, already nearly buried, so increasing would be a very abnoxious option for me. Before you suggest a disclaimer that the un-assembled version is strictly for expert SMD solderers and is unsupported (and sparsely documented, unless I am to spend a lot of time writing and maintaining a second manual version): in my limited experience there are also a large proportion of people for whom any form of warning, particularly if written in bold red font potentially larger size than normal, magically renders itself as completely invisible to their eyes. This is an as yet unresolved mystery but has been consistently observed on multiple occasions.

Then there's my other observation, that regardless of the size of stick used to beat kit packers, the probability of packing error (missing or wrong components) is strictly inversely proportional to the size of the components being packed. 

All in all offering such a kit version, having unassembled SMD, appears to me terribly unfeasible. 

The hard-core sadistic fanatic (not suggesting necessarily that this includes you Janez OM) could always use hot air to remove all SMD components from the assembled boards, then have fun identifying all the tiny grains and cleaning everything up and then re-soldering them to his heart's content...

73 Hans G0UPL 


On Sat, Sep 12, 2020, 22:21 Janez S58J <janez.s58j@...> wrote:
I am really impressed Hans. QCX-mini is another TRX on my must-have list.

Just one simple question: will it be possible to get the "mini" with SMD parts NOT pre-assembled? I am not asking this to get a lower price and I am willing to pay the full cost. I just wish to do it all by myself. To me it is a special feeling by soldering every single part and making the device alive. Plus I am very used to soldering SMD parts with great tools available (Hakko ...). I already made 5 different QRP transceivers, ranging from HF all the way to 13cm (2304/2320 MHz), each time by having only PBCs and the case and that is where I have most of the fun.

Looking forward to your reply.

Janez, S58J  

V V pet., 11. sep. 2020 ob 18:23 je oseba Hans Summers <hans.summers@...> napisala:
Hi all

I am excited to provide an update on the QCX-mini project http://qrp-labs.com/qcxmini.html

Again to stress: QCX-mini has the same schematic (almost), firmware, operation and performance as QCX and QCX+. It is just a different physical manifestation. This is not a major R&D effort. It is a pleasant breather. The tasks are limited to mechanical re-engineering and some re-documentation later. So please don't all start yelling at me about what I ought to be spending my time and energy on instead. 

To summarize: I laid out a PCB. Two in fact (it's a sandwich). And got some made. I have ordered two sets of components and one set arrived yesterday; the other (the bulk of the R and C, SMD parts from Farnell UK) will arrive in about 1 week. I designed an enclosure and made technical drawings, and my usual enclosure factory has produced a prototype to my specification, which is in the post and will likely get here in about 2 weeks from now. 

So far everything fits together very well and at this stage I do not anticipate any major roadblocks. 

It's a really beautiful little radio! I am looking forward to hauling myself to a nearby mountain to try it out. 

73 Hans G0UPL
http://qrp-labs.com


#40m #40m

Don Blachura
 

Hello Folks,
Having built a qcx+ and working fb.
I would like to get the cat to work for me. Can any show or help me set it up. What do I need and
how do I set it up? Not a tech, but can follow instructions well.

Don...w2xb


Re: Building QCX and L1, L2, L3

Curt wb8yyy
 

Phil

If you want to experiment with the lpf toroids, don't solder them into the holes. Instead tack solder them to the leads of the capacitors where they mate. Wish I would have thought of this.

Actually I think the topic is a bit exaggerated. I took one turn off my 80m qcx plus inductors, gained about a quarter watt, and stopped there. The difference between 3.25 watts and 5 watts is mighty small. But have fun, tack them down and see what you get.

73 curt


Re: Compressing or expanding turns on a toroid.

Alan G4ZFQ
 

My  understanding is that all one changes by compressing and expanding the turns is that one changes the distributed capacitance and not the inductance. Looking at the formula for the inductance of a toroid I see inductance being dependent on the number of turns squared, the cross
As a retired motor technician maybe I'm not qualified to wonder if it is possible to measure inductance? Do we just measure the apparent inductance?
All inductors must have distributed capacitance, does the formula take that into account? Certainly squeezing/stretching the coil must alter the capacitance?

73 Alan G4ZFQ


Re: Building QCX and L1, L2, L3

N3MNT
 

I know it is not a QCX, but same LPFs .  I just built 6 LPFs for a U3S.  Measured with NA worst was 0.3db down at operating Freq.


Re: Compressing or expanding turns on a toroid.

Manuel; DL2MAN
 

Hi, 

You can actually measure, that inductance gets higher when compressing the windings. Either by LC meter or nano vna. 
The Inductance for a toroid is always calculated /given with the assumption of e.g. equally spaced windings over 3/4 of core.
If you change the spacing, you change the Inductance.
The more dispersed the windings are the lower the inductance. The more dense the windings are the higher the inductance.

73 Manuel; DL2MAN


Re: Building QCX and L1, L2, L3

Hans Summers
 

Hi Janez, all

All the capacitors supplied in the LPFs are high quality NP0/C0G 50V ceramics made by Vishay and supplied by Digikey US. There should never be any need to replace these capacitors to get the full power output.

73 Hans G0UPL 

On Sat, Sep 12, 2020, 22:58 Janez S58J <janez.s58j@...> wrote:
It depends. Having a good LCR meter is very useful so you won't need to do the desoldering . My experience was (for 30m and 20m versions) that I needed to remove 1-2 windings to get closer to the needed impedance. That, combined with quality NP0 (C0G) capacitors in the filter (all SMD, size 0805, rated for 100V,  simply soldered between the holes where C5, C8, C25, C26, C27, C28 and C30 are positioned) resulted in 4.5W output on the first attempt and later I haven't even touched the toroids (i.e. tweaking the space between the windings).

Kind regards

Janez, S58J

V V sob., 12. sep. 2020 ob 21:25 je oseba Phil N6WKZ <n6wkz@...> napisala:
I'm beginning to wind the toroids for the QCX.

Should I wind according to the manual or take 1 turn off each before
installing?

What is the general consensus?

I'd like to minimize the de-soldering if possible.

73 Phil N6WKZ




19521 - 19540 of 71764