Topics

Are these LPF capacitors out of spec? #qcx #lpf #parts

HF
 

Hi all... I've been reading on this forum that there have been some issues with the bluish capacitors for the QCX low pass filters.  I recall that the matter is on Hans' list to investigate, but haven't seen an announcement from him about his conclusions yet.  I ordered an LCR meter (marked LCR-T5, has a red PCB with lever socket and buttons marked OFF and TEST) on ebay to check mine.  I'm now building my QCX (20m version).  The nominally 390 pF capacitors C25 and C26 measure at 368 and 370 pF.  The nominally 180 pF capacitors C27 and C28 measure at 164 and 172 pF.  The meter doesn't show them as being particularly lossy.  I don't know the claimed tolerance for these capacitors, so I don't know if being off by 5-9% is significant, nor do I know whether this inexpensive LCR meter is capable of measuring to 5% accuracy. Is this enough information to decide whether to order alternates?
Halden NR7V

Arv Evans
 

Halden NR7V

Running the filter design in a circuit simulator like LTSpice and using Monte-carlo
analysis should show the effect on performance at various levels of tolerance. 

http://electronicsbeliever.com/monte-carlo-simulation-using-ltspice-step-by-step-tutorials/

I have the same meter and find it to not be as accurate as a good lab-grade instrument,
but it is quick and accurate for checking components before soldering them into a board.

Arv  K7HKL
_._


On Sat, Aug 11, 2018 at 3:41 PM HF via Groups.Io <incorridge=yahoo.com@groups.io> wrote:
Hi all... I've been reading on this forum that there have been some issues with the bluish capacitors for the QCX low pass filters.  I recall that the matter is on Hans' list to investigate, but haven't seen an announcement from him about his conclusions yet.  I ordered an LCR meter (marked LCR-T5, has a red PCB with lever socket and buttons marked OFF and TEST) on ebay to check mine.  I'm now building my QCX (20m version).  The nominally 390 pF capacitors C25 and C26 measure at 368 and 370 pF.  The nominally 180 pF capacitors C27 and C28 measure at 164 and 172 pF.  The meter doesn't show them as being particularly lossy.  I don't know the claimed tolerance for these capacitors, so I don't know if being off by 5-9% is significant, nor do I know whether this inexpensive LCR meter is capable of measuring to 5% accuracy. Is this enough information to decide whether to order alternates?
Halden NR7V

Leland L. Bahr
 

Your capacitors are most likely as marked.  An LCR meter will show different readings depending on the frequency used by the meter.  If your meter would use a lower frequency, the capacitance shown would be higher.  That's a problem when a specific capacitance or inductance is specified as the value will be different at different frequencies.  (The lower the frequency the lower the measured capacitance.)  Unfortunately the frequency for the specified value is rarely given or mentioned.   Without knowing the frequency for a specific value, the specified value is sort of meaningless.  Frequency for measured value  is just important to know as the part's tolerance.   Also, the heat generated in a capacitor can greatly change it's value and can cause trouble in tuned circuits.  I suspect the issues in the pi network of a QCX are more related to capacitance change and losses due to heat in the capacitor then from capacitor tolerance. 

Lee

w0vt, w5drc


On 8/11/2018 4:40 PM, HF via Groups.Io wrote:
Hi all... I've been reading on this forum that there have been some issues with the bluish capacitors for the QCX low pass filters.  I recall that the matter is on Hans' list to investigate, but haven't seen an announcement from him about his conclusions yet.  I ordered an LCR meter (marked LCR-T5, has a red PCB with lever socket and buttons marked OFF and TEST) on ebay to check mine.  I'm now building my QCX (20m version).  The nominally 390 pF capacitors C25 and C26 measure at 368 and 370 pF.  The nominally 180 pF capacitors C27 and C28 measure at 164 and 172 pF.  The meter doesn't show them as being particularly lossy.  I don't know the claimed tolerance for these capacitors, so I don't know if being off by 5-9% is significant, nor do I know whether this inexpensive LCR meter is capable of measuring to 5% accuracy. Is this enough information to decide whether to order alternates?
Halden NR7V

John Pagett
 

Hi Halden,
I don't believe that measuring the capacitance value helps in this case. My 30m QCX was low on power and replacing the two blue capacitors C25 and C26 was a big improvement. Before I replaced the capacitors I traced the filter response using a Raspberry Pi Wobbulator, and did the same after replacement.
The trace with the original capacitors was a slightly odd shape around 10 MHz but (from memory) only about 1dB below the reference. The results are on my computer but I can't get to it at the moment.
The trace with the new capacitors was still at reference at 10 MHz.

The old capacitors checked out as very close to nominal on my cheap component tester  so that doesn't help.

My conclusion is that the original capacitors are somehow sensitive to the signal levels applied. They are ok with low level signals from the test circuits but not once significant voltage/current is present.
I've been meaning to post these results but I have some more graphs to plot yet and further tests to perform, but I felt your question demanded an answer.

73
John
G4YTJ


Alan Richmond
 

The LC 100-A from china claims 1% accuracy for L and C over the important part of its measuring range. Priced at just under £10 it's not a big risk; I have one on order, but it has not arrived yet. Any serious builder or repairer should have an instrument like this, IMHO.

Alan G4ZFQ
 

The LC 100-A from china claims 1% accuracy
Alan,

Take no notice of Chinese claims.
I had one that quoted 1%, it was about -20% for normal values.
I have one that did not quote any accuracy, it IS around 1%.
The only way to be sure is to have some 1% capacitors and inductors as a reference.

I keep on reading about frequency of measurement. In my experience for normal QRP Labs components it makes no difference. I check with a GDO at working frequency or a meter at around 500KHz getting very similar readings.

The capacitors C25 and C26 have been questioned several times.
Some have said low power, then they get hot and power increases a bit.
Hans seems to not have reached a conclusion.
My guess is that a proportion of a batch of these were lossy. As far as I remember replacement has always solved the problem.

73 Alan G4ZFQ

Alan G4ZFQ
 

I had one that quoted 1%, it was about -20% for normal values.
I have one that did not quote any accuracy, it IS around 1%.
The one I tested https://sites.google.com/site/alan4alan/lc100a_term_on_right

73 Alan G4ZFQ

Alan Richmond
 

Thanks, Alan,

forewarned is forearmed!

I have been suplied with some pretty bad items from China, though they are in the minority. Ebay offers some protection, as you can give the supplier a bad rating where necessary, and use their process to obtain a refund.

I told one supplier that his product was dead on arrival, and he asked if I wanted a refund or replacement. I asked for a replacement, and he sent two!

I'll keep my fingers crossed for luck on this one, and test it against some low-tolerance components when I can.

best regards

Alan
GU3ONJ

Clint Sharp <cjaysharp@...>
 

One thing I would add to this conversation, the ATMega328 based LCR meters are copies of an open source meter that’s been developed and maintained by a group of electronics hobbyists, the original source was a pair of German hobbyists and their websites is still up with a very active user group. 

There’s also a long running thread on EEVBlog forum, I think it’s titled ‘$20 LCR meter’ or similar and is well worth a read for the many enhancements and updates to this elegant design. 

The meters can be accurate, there will probably be a built in calibration routine which is very simple to complete, the cheap 2x16 LCD version I have compares favourably to my Agilent LCR meter as well as being ‘spot on’ with some close tolerance polystyrene capacitors I have. 

Where they can fall down is if the kit doesn’t have a ‘proper’ voltage reference, they have been spotted using a zener or even resistive divider. 

On Sun, 12 Aug 2018 at 10:12, Alan Richmond <richmond@...> wrote:
Thanks, Alan,

forewarned is forearmed!

I have been suplied with some pretty bad items from China, though they are in the minority. Ebay offers some protection, as you can give the supplier a bad rating where necessary, and use their process to obtain a refund.

I told one supplier that his product was dead on arrival, and he asked if I wanted a refund or replacement. I asked for a replacement, and he sent two!

I'll keep my fingers crossed for luck on this one, and test it against some low-tolerance components when I can.

best regards

Alan
GU3ONJ

--
Clint. M0UAW IO83

No trees were harmed in the sending of this mail. However, a large number of electrons were greatly inconvenienced.

jmh6@...
 

Hi All,

"Lossy capacitors". Amazing. Yup.

Measuring components is NON-TRIVIAL. Resistors change with applied voltage and temperature. Inductors are lossy. Caps.... It seems like another chapter has been added to the problems with capacitors book :).

Gotta work hard to make capacitors that do not work well! I wonder what was really done to make them that 'bad'?

Lots of fun :).

John

On Sun, 12 Aug 2018, Alan G4ZFQ wrote:

The LC 100-A from china claims 1% accuracy
Alan,

Take no notice of Chinese claims.
I had one that quoted 1%, it was about -20% for normal values.
I have one that did not quote any accuracy, it IS around 1%.
The only way to be sure is to have some 1% capacitors and inductors as a reference.

I keep on reading about frequency of measurement. In my experience for normal QRP Labs components it makes no difference. I check with a GDO at working frequency or a meter at around 500KHz getting very similar readings.

The capacitors C25 and C26 have been questioned several times.
Some have said low power, then they get hot and power increases a bit.
Hans seems to not have reached a conclusion.
My guess is that a proportion of a batch of these were lossy. As far as I remember replacement has always solved the problem.

73 Alan G4ZFQ



James Daldry W4JED
 

50 years of TV service taught me that anywhere you have high frequency AC and significant power you have to be choosy of the capacitors you use. I've seen many ceramics split in 2 along the edge, and even silver micas develop holes. You never put a ceramic that doesn't have a temperature rating (NP0, N750, etc) in a TV horizontal output circuit. It will die within seconds from dielectric heating.

In the mid 1970's UL decided that using a single capacitor to tune the flyback circuit in a TV was a bad idea, since if the cap opened the high voltage would go up and Xray the viewers. So a clever cap manufacturer came out with the 4-lead capacitor - a wire at each end of the 2 layers of foil. One end would go in series with the collector of the horizontal output transistor, and the other at the emitter. Any wire coming loose would stop the machine. Problem was, the company Zenith bought their caps from made the caps from lead foil instead of aluminum, since lead makes a much better connection to tinned copper than aluminum. So no oxidized aluminum to copper connections. Fewer failures. Problem was, with age and extended operation, the dielectric loss would allow the lead to get hot enough to melt and wick itself to the ends of the cap. Normal HV on these sets was 30 thousand volts. When the cap did its wick job, the capacitor was no longer a capacitor and the HV would go to 80KV. The HV would arc through the neck of the picture tube to one of the convergence yoke pole pieces, blowing the vertical output transistors. Loud pop, circuit breaker trips. $250 repair on a $400 set. Luckily, almost all of them failed in warranty, the capacitor maker (American Radionics) lost the lawsuit, and everybody lived happily after. The replacement caps came from Sprague, and none of them failed.

Lossy capacitors are everywhere. Electrolytics are lossy. Any ceramic without a temperature tolerance marking is lossy. Wax paper caps are lossy.

Jim Daldry

On 08/12/2018 04:44 AM, jmh6@... wrote:

Hi All,

  "Lossy capacitors". Amazing. Yup.

  Measuring components is NON-TRIVIAL. Resistors change with applied voltage and temperature. Inductors are lossy. Caps.... It seems like another chapter has been added to the problems with capacitors book :).

  Gotta work hard to make capacitors that do not work well! I wonder what was really done to make them that 'bad'?

  Lots of fun :).

  John


On Sun, 12 Aug 2018, Alan G4ZFQ wrote:

The LC 100-A from china claims 1% accuracy
Alan,

Take no notice of Chinese claims.
I had one that quoted 1%, it was about -20% for normal values.
I have one that did not quote any accuracy, it IS around 1%.
The only way to be sure is to have some 1% capacitors and inductors as a reference.

I keep on reading about frequency of measurement. In my experience for normal QRP Labs components it makes no difference. I check with a GDO at working frequency or a meter at around 500KHz getting very similar readings.

The capacitors C25 and C26 have been questioned several times.
Some have said low power, then they get hot and power increases a bit.
Hans seems to not have reached a conclusion.
My guess is that a proportion of a batch of these were  lossy. As far as I remember replacement has always solved the problem.

73 Alan G4ZFQ




Arv Evans
 

On Sun, Aug 12, 2018 at 4:57 AM Clint Sharp <cjaysharp@...> wrote:
One thing I would add to this conversation, the ATMega328 based LCR meters are copies of an open source meter that’s been developed and maintained by a group of electronics hobbyists, the original source was a pair of German hobbyists and their websites is still up with a very active user group. 

There’s also a long running thread on EEVBlog forum, I think it’s titled ‘$20 LCR meter’ or similar and is well worth a read for the many enhancements and updates to this elegant design. 

The meters can be accurate, there will probably be a built in calibration routine which is very simple to complete, the cheap 2x16 LCD version I have compares favourably to my Agilent LCR meter as well as being ‘spot on’ with some close tolerance polystyrene capacitors I have. 

Where they can fall down is if the kit doesn’t have a ‘proper’ voltage reference, they have been spotted using a zener or even resistive divider. 

On Sun, 12 Aug 2018 at 10:12, Alan Richmond <richmond@...> wrote:
Thanks, Alan,

forewarned is forearmed!

I have been suplied with some pretty bad items from China, though they are in the minority. Ebay offers some protection, as you can give the supplier a bad rating where necessary, and use their process to obtain a refund.

I told one supplier that his product was dead on arrival, and he asked if I wanted a refund or replacement. I asked for a replacement, and he sent two!

I'll keep my fingers crossed for luck on this one, and test it against some low-tolerance components when I can.

best regards

Alan
GU3ONJ

--
Clint. M0UAW IO83

No trees were harmed in the sending of this mail. However, a large number of electrons were greatly inconvenienced.

zl1ujg
 

Hi,
Many years ago, I wrote an article about lossy capacitors..
Which I still stand by.. (In fact Hans and I chatted about it a week or so back)

Simple LCR meters only paint a picture of value and tolerance. There are certainly some low tolerance capacitors.

Something like a simple  Q meter, driven by a SI5351, might give an idea of Q at the frequencies in question.

Recently while prototyping a 80m Bandpass filter on a Lowpass filter board.. I ran into extra losses..
In fault finding, it turned out one of the blue capacitors seemed to have gone low capacitance (560pF to only a few pF)
It was all in one piece.. And repeated measurements in and out of circuit gave the same result..

The  toroidal handwound inductors can be close to the value, and typically sit a few % points higher when using meters like the AADE, which have compared well to commercial meters in the 300kHz range. I have found the toroids.info winding info very accurate.

I had bought some blue toroid cores recently off one of the online sellers.. and found that although the value of inductance was correct when wound.. The loss at the frequency in question (80m) was terrible. About 10-11 dB for a  3 toroid 80m Band Pass filter.. I checked the  toroid Q using a simple notch circuit, and it was about 10.. Rewound the inductors onto T50-2 cores, and replaced the 3 in the  circuit ...under 1 dB loss.. 
(Experimenting with PA3AKE bandpass filters on a QRPLabs LPF PCB)


The normally unpainted side of these lossy cores was a lighter grey finish, rather than the dark grey/tending towards black finish of most cores

So buyer beware.. 

These are probably made of moulded rust..

Kevin







J68HZ
 

I would say that most LCR meters barely paint a picture of a capacitor or inductor at the frequency the LCR meter operates at… and for most of these devices that is maybe 100KHz…  Is that where you operate? Maybe for audio work…  If you really want to know about your capacitors and inductors, build a test jig for the frequency(ies) of operation and test it in a real Z situation.  If you don’t you are kidding yourself.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook!

 

Moderator – North American QRO Group at Groups.IO.

 

email:  bill@...

 

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of zl1ujg via Groups.Io
Sent: Sunday, August 12, 2018 1:56 PM
To: qrplabs@groups.io
Subject: Re: [QRPLabs] Are these LPF capacitors out of spec?

 

Hi,

Many years ago, I wrote an article about lossy capacitors..

Which I still stand by.. (In fact Hans and I chatted about it a week or so back)

 

Simple LCR meters only paint a picture of value and tolerance. There are certainly some low tolerance capacitors.

 

Something like a simple  Q meter, driven by a SI5351, might give an idea of Q at the frequencies in question.

 

Recently while prototyping a 80m Bandpass filter on a Lowpass filter board.. I ran into extra losses..

In fault finding, it turned out one of the blue capacitors seemed to have gone low capacitance (560pF to only a few pF)

It was all in one piece.. And repeated measurements in and out of circuit gave the same result..

 

The  toroidal handwound inductors can be close to the value, and typically sit a few % points higher when using meters like the AADE, which have compared well to commercial meters in the 300kHz range. I have found the toroids.info winding info very accurate.

 

I had bought some blue toroid cores recently off one of the online sellers.. and found that although the value of inductance was correct when wound.. The loss at the frequency in question (80m) was terrible. About 10-11 dB for a  3 toroid 80m Band Pass filter.. I checked the  toroid Q using a simple notch circuit, and it was about 10.. Rewound the inductors onto T50-2 cores, and replaced the 3 in the  circuit ...under 1 dB loss.. 

(Experimenting with PA3AKE bandpass filters on a QRPLabs LPF PCB)

 

 

The normally unpainted side of these lossy cores was a lighter grey finish, rather than the dark grey/tending towards black finish of most cores

 

So buyer beware.. 

 

These are probably made of moulded rust..

 

Kevin

 

 

 

 

 

 

 


Virus-free. www.avg.com

James Daldry W4JED
 

Not out of spec. Excessive dielectric loss.

BTW. When you cook food in a microwave oven, that's dielectric loss in action. Especially the part when fats catch fire.

Jim Daldry


On 08/12/2018 11:25 AM, Arv Evans wrote:

On Sun, Aug 12, 2018 at 4:57 AM Clint Sharp <cjaysharp@...> wrote:
One thing I would add to this conversation, the ATMega328 based LCR meters are copies of an open source meter that’s been developed and maintained by a group of electronics hobbyists, the original source was a pair of German hobbyists and their websites is still up with a very active user group. 

There’s also a long running thread on EEVBlog forum, I think it’s titled ‘$20 LCR meter’ or similar and is well worth a read for the many enhancements and updates to this elegant design. 

The meters can be accurate, there will probably be a built in calibration routine which is very simple to complete, the cheap 2x16 LCD version I have compares favourably to my Agilent LCR meter as well as being ‘spot on’ with some close tolerance polystyrene capacitors I have. 

Where they can fall down is if the kit doesn’t have a ‘proper’ voltage reference, they have been spotted using a zener or even resistive divider. 

On Sun, 12 Aug 2018 at 10:12, Alan Richmond <richmond@...> wrote:
Thanks, Alan,

forewarned is forearmed!

I have been suplied with some pretty bad items from China, though they are in the minority. Ebay offers some protection, as you can give the supplier a bad rating where necessary, and use their process to obtain a refund.

I told one supplier that his product was dead on arrival, and he asked if I wanted a refund or replacement. I asked for a replacement, and he sent two!

I'll keep my fingers crossed for luck on this one, and test it against some low-tolerance components when I can.

best regards

Alan
GU3ONJ
--
Clint. M0UAW IO83

No trees were harmed in the sending of this mail. However, a large number of electrons were greatly inconvenienced.


lajes67
 

     About 8 years ago, our club started kit building as a club project, to say we bit off more than we could chew is to say the least, our first project was what is now known as the Five Dash Kit Softrock RXTX Ensemble Transceiver kit.

     What started off as a $79.00 (then) kit quickly ballooned to an outlay of a couple of hundred dollars of tools and test equipment, among the many components to build were the coils for the specific bands being used, of course the instructions said to wind so many turns but we noticed a difference when we tested that stage.  
     I looked on line and ordered an LC meter, commercial made, it wouldn't measure any of the coils that we made so I did another search, this time for LC kits, I did find one, ordered and built the kit and it was able to measure every coil that I have since made,  I don't have meter near me but unfortunately the Gentleman became a silent key about 4 years ago and the kits are no longer available.
    If I remember correctly I think the fact that the kit worked and the commercial one didn't was the reference frequency that was used in the kit, IMHO a lot of kit builders have found that commercial made test equipment doesn't work for QRP designed equipment, lucky I was able to sell the commercial meter and recover most of the money I put out.

     My QCX and Soft Rock kits might not be in the same price range of a modern HF rig, but they are a learning experience to build and get on the air and there is the self satisfaction, to me, of seeing how far away I can make a contact.

73 John Smale K2IZ

Alan G4ZFQ
 

About 8 years ago, our club started kit building as a club project, to say we bit off more than we could chew is to say the least, our first project was what is now known as the Five Dash Kit Softrock RXTX Ensemble Transceiver kit.
     What started off as a $79.00 (then) kit quickly ballooned to an outlay of a couple of hundred dollars of tools and test equipment, among the many components to build were the coils for the specific bands being used, of course the instructions said to wind so many turns but we noticed a difference when we tested that stage.
John,

As someone who has been in the Softrock group for more than 8 years may I just say that the greater majority of constructors did it with just an iron and a DVM.
Yes, coils did not, like QRP Labs, always measure exactly but most times they were close enough that performance was not affected. Where performance was compromised simple turns adjustment, like in QRP Labs projects was all that was needed.
Tony is still with us but Parkinson's has curtailed his activity.

73 Alan G4ZFQ

Hans Summers
 

FYI the forthcoming QSX contains a built-in inductance meter for checking the values of the inductors used in the Band pass and Low pass filters. The measurement is performed close to the operating frequency. During the YOTA 2018 buildthon we typically found the inductance was on high side as wound, and had to remove one turn. 

This is also as expected since the theoretical calculation for number of turns assumes 360-degree coverage which is never the case in practice. Nor should it be: a 30-degree gap between the winding ends is typically used to manage the effect of parasitic capacitance between the ends. 

So for example, L1 and L3 in the LPF are specified 1.38uH which is 21 turns. Typically we needed to remove one turn to 20 turns, to get it down to around 1.38uH.

Hopefully the built-in inductance meter will help remove one more construction variable.

73 Hans G0UPL 

On Mon, Aug 13, 2018, 21:25 Alan G4ZFQ <alan4alan@...> wrote:
> About 8 years ago, our club started kit building as a club project, to say we bit off more than we could chew is to say the least, our first project was what is now known as the Five Dash Kit Softrock RXTX Ensemble Transceiver kit.
>
>       What started off as a $79.00 (then) kit quickly ballooned to an outlay of a couple of hundred dollars of tools and test equipment, among the many components to build were the coils for the specific bands being used, of course the instructions said to wind so many turns but we noticed a difference when we tested that stage.

John,

As someone who has been in the Softrock group for more than 8 years may
I just say that the greater majority of constructors did it with just an
iron and a DVM.
Yes, coils did not, like QRP Labs, always measure exactly but most times
they were close enough that performance was not affected. Where
performance was compromised simple turns adjustment, like in QRP Labs
projects was all that was needed.
Tony is still with us but Parkinson's has curtailed his activity.

73 Alan G4ZFQ



Alan de G1FXB
 

Great News !

an excuse if needed, to buy a piece of accurate test equipment & get a world beater of a TRX thrown in for free....


Alan


On 17/08/2018 10:07, Hans Summers wrote:
FYI the forthcoming QSX contains a built-in inductance meter for checking the values of the inductors used in the Band pass and Low pass filters. The measurement is performed close to the operating frequency. During the YOTA 2018 buildthon we typically found the inductance was on high side as wound, and had to remove one turn. 

This is also as expected since the theoretical calculation for number of turns assumes 360-degree coverage which is never the case in practice. Nor should it be: a 30-degree gap between the winding ends is typically used to manage the effect of parasitic capacitance between the ends. 

So for example, L1 and L3 in the LPF are specified 1.38uH which is 21 turns. Typically we needed to remove one turn to 20 turns, to get it down to around 1.38uH.

Hopefully the built-in inductance meter will help remove one more construction variable.

73 Hans G0UPL 

On Mon, Aug 13, 2018, 21:25 Alan G4ZFQ <alan4alan@...> wrote:
> About 8 years ago, our club started kit building as a club project, to say we bit off more than we could chew is to say the least, our first project was what is now known as the Five Dash Kit Softrock RXTX Ensemble Transceiver kit.
>
>       What started off as a $79.00 (then) kit quickly ballooned to an outlay of a couple of hundred dollars of tools and test equipment, among the many components to build were the coils for the specific bands being used, of course the instructions said to wind so many turns but we noticed a difference when we tested that stage.

John,

As someone who has been in the Softrock group for more than 8 years may
I just say that the greater majority of constructors did it with just an
iron and a DVM.
Yes, coils did not, like QRP Labs, always measure exactly but most times
they were close enough that performance was not affected. Where
performance was compromised simple turns adjustment, like in QRP Labs
projects was all that was needed.
Tony is still with us but Parkinson's has curtailed his activity.

73 Alan G4ZFQ