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Re: Removing flux. Is it necessary? Yes/No

 

On Sat, Sep 21, 2024 at 11:29 AM, Tony Scaminaci wrote:
Second, it makes looking for solder bridges, shorts, and cold solder points much easier.
The cleaning process will direct your attention to each area, kind of like hand-washing your car will allow you to find those little dings and scratches you would never have noticed if using the car wash.
Extra style points for cleaning and inspecting under 8X-10X binocular magnification.
73, Don N2VGU
Re: Qdx tcxo problems?

 

On Sat, Sep 21, 2024 at 08:19 AM, Alan G4ZFQ wrote:
Others have cut the IC pins with a Dremel-type tool or even with a scalpel.
A scalpel blade, specifically a #15 blade, applied with a rocking motion adjacent to the IC body, will slice cleanly through the leads without putting undue stress on the PCB lands.
Then merely individually heat and pluck off the leads, clean up the lands and you are ready to reinstall.
Good luck and 73, Don N2VGU
Re: Removing flux. Is it necessary? Yes/No

 

I took Jeff Moore's advice and bought a pint of 99% isopropyl alcohol from Amazon ( about $9).
Much better than even 91%.?

A little goes a long way. Really cleans quick and leaves little or no smeary residue.

Greg


On Sat, Sep 21, 2024 at 12:40 PM, Bruce Akhurst
<bruce@...> wrote:
'Flux rarely causes a problem during the warranty period - especially the no-clean stuff'

But years-on in certain circumstances of temperature and humidity it can become a problem for RF and power circuitry?

I generally clean it off.? ?The no clean fluxes may require a specific cleaner like ECSP or FLU FluxClene? (both of which can often be ordered with a handy Brush) but many fluxes come off with just Isopropyl Alcohol
Re: 180pf (181) Capacitor Needed

 

Digikey or Mouser are good sources.

Shipping and handling will likely be more than the parts you buy, but stocking up on regular spares, general kit building supplies and such at the same time that can come in one package will ease that hit.?

Potentially available from Amazon or eBay but provenance may be iffy.?

Greg


On Sat, Sep 21, 2024 at 12:47 PM, Bill Jobes via groups.io
<jobes@...> wrote:
Due to damage I caused (small crack)? I need to replace the 180pf cap in my QMX + build.
?
Can anyone please link a reliable source where I can purchase one and a few spares? The Shop doesn't list caps among spare parts.?
?
Thanks !
?
- Bill? W3WJ?
Re: Qdx tcxo problems?

 

A soldering station with hot air is affordable and worth having.? ?I use YIHUA 8786D
Transverters?

 

Hi all,?

I’m interested in using a QMX with transverters for 4 meters/ 2 meters and 70 cms. But there seems to be a lack of modern DIY kits or designs for them. Any suggestions??

My FT817 has expired and if I can’t repair it ?I’ll be without its higher bands. It’s a complicated design and quite old so spares are a problem. What I would really like to do is move to a situation where I’ve built everything I use which should mean I could fix radios when they break. Hence my interest in transverters.?

Stay safe,?

Steve G0XAR?
Re: iFTX

 

Your comments are greatly appreciated!!!! 72 Luis


El El sáb, 21 sept 2024 a la(s) 13:27, VA3CJO - Chris "CJ" via <va3cjo=[email protected]> escribió:

Others already pointed you to the right adaptors.
?
I'll add that I often use iFTx with an iPhone and it works well, with a caveat: Apple places artificial limitations on the iPhone and it won't do CAT control.
?
To get PTT working, you set the QMX to "VOX" as was pointed out earlier in this discussion. You may have to tweak some threshold values on the QMX to make this work smoothly.
?
Further, since there's no CAT control, you have to manually select the band in the iFTx app, and set the band/frequency on the QMX. (e.g.: you set iFTx to 20m band, manually change the QMX to "14.074MHz", the standard 20m FT8 frequency) You can make this less cumbersome by saving all the FT8 and FT4 standard frequencies as on the QMX and just toggling between them.
?
Note that you don't have to adjust this when you change the transmit tone. The app will adjust the tone to whatever you've set (say, "1500Hz"), similar to operating in "Fake It" mode in WSJT-x instead of full "Split" mode.
?
?
180pf (181) Capacitor Needed

 

Due to damage I caused (small crack)? I need to replace the 180pf cap in my QMX + build.
?
Can anyone please link a reliable source where I can purchase one and a few spares? The Shop doesn't list caps among spare parts.?
?
Thanks !
?
- Bill? W3WJ?
Re: QMX (not-plus) power issue

 

p.s. to my prior post: oops, my QMX is built for 9V, so 125mA at 9V is about the same as 90mV at 12V from the prior posts.? So you do have a higher than normal idle current draw.
But since you are getting a full 5+W on the lower two bands, I don't know how it can be a problem with the BS170s.? Based on other posts I have read here, I don't think you can expect a full 5W on 20M, either.? There is definitely an issue on 20M and probably 30M on your device - so since those two bands share the same filter, that's the first place I would look.
Stan
Re: Removing flux. Is it necessary? Yes/No

 

'Flux rarely causes a problem during the warranty period - especially the no-clean stuff'

But years-on in certain circumstances of temperature and humidity it can become a problem for RF and power circuitry?

I generally clean it off.? ?The no clean fluxes may require a specific cleaner like ECSP or FLU FluxClene? (both of which can often be ordered with a handy Brush) but many fluxes come off with just Isopropyl Alcohol
Re: QMX (not-plus) power issue

 

I wouldn't assume you have a problem in the BS170s.
My newly built QMX mini draws 125mA on idle/receive, and all diagnostic tests work correctly, and it seems to receive and transmit correctly.? There may be something wrong that I am not aware of, but all seems ok so far.
On transmit it draws about 1.25A.
I also have a cross-needle power/swr meter (MFJ-880), and its power readings match almost exactly the ones from the QMX diagnostic menu.? So I don't know what the issue is there for you.? The QMX reads the power directly from its SWR bridge at the output, so there isn't much in the pathway between that and an external meter except cables and connectors.
It is a well-known fact that the QMX (and QDX and QCX) output lower power on the upper bands.? Full 5W power on the low two bands, and gradually decreasing to 3W or so the top band.? Your 20M power is lower than it should be, but since the other bands seem correct, it is likely not a BS170 issue.? Search the prior messages here for 20M low power or low power and you will find several threads discussing this and what people have done to try and remedy.? I think mostly it is adjusting the position of windings on toroids.? You may also have a bad/wrong value capacitor in the 20M filter which could contribute to this.? Does the LPF sweep and Bandpass filter sweep function from the diagnostic menu for 20M give results that look very much like the ones in the operations manual? If not, the filters are the first place to check.
Re: iFTX

 

Others already pointed you to the right adaptors.
?
I'll add that I often use iFTx with an iPhone and it works well, with a caveat: Apple places artificial limitations on the iPhone and it won't do CAT control.
?
To get PTT working, you set the QMX to "VOX" as was pointed out earlier in this discussion. You may have to tweak some threshold values on the QMX to make this work smoothly.
?
Further, since there's no CAT control, you have to manually select the band in the iFTx app, and set the band/frequency on the QMX. (e.g.: you set iFTx to 20m band, manually change the QMX to "14.074MHz", the standard 20m FT8 frequency) You can make this less cumbersome by saving all the FT8 and FT4 standard frequencies as on the QMX and just toggling between them.
?
Note that you don't have to adjust this when you change the transmit tone. The app will adjust the tone to whatever you've set (say, "1500Hz"), similar to operating in "Fake It" mode in WSJT-x instead of full "Split" mode.
?
?
Re: Removing flux. Is it necessary? Yes/No

 

Isopropyl alcohol works well and I prefer brands containing 99%. I use cotton swabs soaked in alcohol to clean around pads. The wet end does the cleaning and then I use the dry end to wipe up the residue. A toothpick works well to remove any leftover swab fibers.

Tony

On Sat, Sep 21, 2024 at 10:55?AM Michael - WD0OM via <wd0om=[email protected]> wrote:
Also, as I understand it, simple rubbing alcohol suffices as flux-cleaner, so it's not a big deal. I've been using alcohol-wipe pads I had on hand (being careful not to leave behind fibers from the pad), which I'm sure is not ideal, but seems to clean the board up pretty well.

/m

On Sat, Sep 21, 2024, at 10:28, Tony Scaminaci wrote:
It’s not absolutely?necessary to remove flux but I be always do for two reasons. First, long term, flux could affect the performance of high-impedance points, most notably at RF frequencies. Second, it makes looking for solder bridges, shorts, and cold solder points much easier.

Tony AC9QY

On Sat, Sep 21, 2024 at 10:15?AM Keith Hamilton via <n8cep.keith=[email protected]> wrote:
I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary?? In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary?? I am using good Kester 63/37 solder with flux.
Re: Removing flux. Is it necessary? Yes/No

 

Also, as I understand it, simple rubbing alcohol suffices as flux-cleaner, so it's not a big deal. I've been using alcohol-wipe pads I had on hand (being careful not to leave behind fibers from the pad), which I'm sure is not ideal, but seems to clean the board up pretty well.

/m

On Sat, Sep 21, 2024, at 10:28, Tony Scaminaci wrote:
It’s not absolutely?necessary to remove flux but I be always do for two reasons. First, long term, flux could affect the performance of high-impedance points, most notably at RF frequencies. Second, it makes looking for solder bridges, shorts, and cold solder points much easier.

Tony AC9QY

On Sat, Sep 21, 2024 at 10:15?AM Keith Hamilton via <n8cep.keith=[email protected]> wrote:
I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary?? In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary?? I am using good Kester 63/37 solder with flux.
Re: QMX (not-plus) power issue

 

Roy, thank you. That fits, so far, with what people seem to describe as part of the cluster of issues around the BS170s. Honestly, even if the BS170s turn out not to be the problem, starting with them seems prudent. They appear to be an Achilles heel. They might have come to me with one already blown, or I might well have blown one myself mishandling power to the device either at input (I did experiment with an "ordinary" radio battery just to see how the protection behaved) or at the output (I have used the device with an autotuner, and that's come up as a possible killer of BS170s).

I have an infrared thermometer, still in its packaging :-D I bought it specifically for future diagnostics like this one. Probably not quite as good as an infrared camera for this, but possibly better than touch alone.

I assume I should remove the retaining washer, or is result something I should be able to easily read with the washer in place?

It may be a few days before I can experiment with it again, but absent other advice, I believe this will be my next investigation.

Thank you!

Michael WD0OM

On Sat, Sep 21, 2024, at 05:10, Roy - KI0ER wrote:
Hi Michael.?
?
When I had a blown PA output transistor, my 12v QMX was drawing a little over 200mA on receive/idle mode. So yours is behaving a little differently at 125mA receive current draw.?
?
In my case one of the 4 PA transistors had an internal short from gate to drain. With the display board removed and the QMX powered up, I could feel (and actually see, since I had an infrared camera) one of my 4 PA transistors was getting quite hot during receive, which should not occur.?
?
You may need help from one of the more knowledgeable electronic gurus, like Ludwig, in diagnosing what's going on.?
?
But, if you can detect one of your 4 PA transistors getting warm in receive mode, then it's probably gone bad and needs to be replaced.?
?
This is more of a hit it with a hammer type of diagnosis. You may need more expert help than I can provide.?
--
73
de Roy - KI0ER
Littleton, Colorado USA
Re: iFTX

 

FT8cn is even more frustrating


El El sáb, 21 sept 2024 a la(s) 11:25, K O K3OX via <kolson=[email protected]> escribió:
Just be aware that iFTX (at least as of 4 to 5 months ago) does not work quite like the FT8 developers designed WSJT. You may like it, I found it frustrating operationally.
?
73, Kevin K3OX
Re: Removing flux. Is it necessary? Yes/No

 

It’s not absolutely?necessary to remove flux but I be always do for two reasons. First, long term, flux could affect the performance of high-impedance points, most notably at RF frequencies. Second, it makes looking for solder bridges, shorts, and cold solder points much easier.

Tony AC9QY

On Sat, Sep 21, 2024 at 10:15?AM Keith Hamilton via <n8cep.keith=[email protected]> wrote:
I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary?? In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary?? I am using good Kester 63/37 solder with flux.
Removing flux. Is it necessary? Yes/No

 

I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary? ?In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary? ?I am using good Kester 63/37 solder with flux.
Re: iFTX

 

Just be aware that iFTX (at least as of 4 to 5 months ago) does not work quite like the FT8 developers designed WSJT. You may like it, I found it frustrating operationally.
?
73, Kevin K3OX
Re: BS170 Heat flow experiment with results (Updated)

 

开云体育

Hi Bill,

The original post had a PDF attachment describing the experiment. I am re-attaching the original PDF to this post. Max-heatsink refers to the original post where the transistors were wrapped in copper tape and soldered to the heatsink.

I did not interpret the data on purpose. Data is data, separate from analysis. But I will point out that hotter heat sink suggests more heat is being transferred so the path from the junction to the heatsink must have a lower thermal resistance.?

This data was presented as a temperature rise above ambient because the ambient varies throughout the day.?

73,

Tony
AD0VC



From:[email protected] <[email protected]> on behalf of Bill <bill@...>
Sent:?Saturday, September 21, 2024 7:50 AM
To:[email protected] <[email protected]>
Subject:?Re: [QRPLabs] BS170 Heat flow experiment with results (Updated)
?
Tony,

Can you explain the meaning of these numbers?? Does a lower number mean the hardware is better able to dissipate heat or simply has more thermal mass for the active device to heat?? Any idea why metal is lower for BS170 but not for TN0110??

I'm also a bit confused by your term "max heatsink". ?What is "max heatsink" if not the fiber or metal hardware you tested...did you also test with some kind of custom heatsink?? If so, it would seem that this heatsink is doing something dramatically different than the typical hardware whether metal or fiber.

?
?
Bill
W2EB
East Syracuse, NY

On 9/20/2024 at 11:05 AM, mux_folder2001 <canthony15@...> wrote:
I ran tests with fiber washer/nylon screw and also with metal washer/metal screw. I also ran the TN0110.

Some experimental noise is evident I think but it is too big of a pain to redo everything. Hopefully some useful insight can be gained from this.






Temperature rise at center of identical heatsinks in degrees C






attached to the respective location




























Case
Drain
Source
Gate

total
BS170 max heatsink
4.5
3.7
2.4
1.9

12.5
BS170 Fiber Washer
3.8
2.4
2.1
1.4

9.7
BS170 Metal Washer
3.1
2.5
1.8
1.3

8.7
TN0110 max heatsink
4.1
3.2
1.6
1.4

10.3
TN0110 Fiber washer
3.3
3.3
1.6
1.4

9.6
TN0110 Metal Washer
4
3.6
1.8
1.5

10.9
TN0110 Reverse metal washer*
3
3.8
1.6
1.6

10







*Flat side against washer, round side against heatsink













Tony
AD0VC

From:[email protected] <[email protected]> on behalf of Hans Summers <hans.summers@...>
Sent:?Thursday, September 12, 2024 12:21 AM
To:[email protected] <[email protected]>
Subject:?Re: [QRPLabs] BS170 Heat flow experiment with results
?
Very nice experiment, Paul

Nice to see some real experimental data.?

I agree with Paul AI7JR, it would perhaps be interesting to measure with only the flat of the transistor face against the copper, since practically in a transceiver the curved part of the body is not touching the copper. I don't think there's any problem with the?measurements though; all the copper plates are the same size with the same dissipation to the environment so it's a reasonable relative comparison.

73 Hans G0UPL


On Thu, Sep 12, 2024 at 7:47?AM Paul - AI7JR via ?<paul.hanchett=[email protected]> wrote:

I wonder if it tells what we want to know...

"Wrap the BS170 case with copper tape and solder it to another copper plate."

In the QMX, only the flat side is connected to the heat sink... (Assuming the washer and screw aren't very significant!) If that were taken into account, heat extraction via the case and via the drain lead might be more comparable, maybe even swapped?


You're making the assumption that temperature at the measurement point is a proxy for power flow on the path. But the actual temperature is a function of the thermal resistance from the measurement point to the environment...


It seems to me that you'd need to standardize the thermal resistance of what you attach the measurement points to, in order to measure relative power flow.


This is giving me a headache! Am I making it harder than it has to be?


Paul -- AI7JR


On 9/11/24 20:42, Sandy via ?wrote:

Hey Tony - That is an interesting result. There is no substitute for actual measurement. This suggests that case contact with the pad is important. I always install the BS170s first with the screw and washer ensuring they are all flat and only then solder in place. Thanks for your efforts! Sandy KB3EOF


On 9/11/24 22:18, mux_folder2001 via ?wrote:
I have attached a PDF file that describes an experiment with the goal of determine where the heat flows in a BS170. The PDF contains pictures of the fixture and a graph of the results. The essence of it is that, given equal opportunity, heat will flow as follows:

  1. Best flow is through the case.
  2. Second best flow is the drain lead.
  3. A distant third is the source lead.
  4. Last is the gate lead.

The graph will give you a sense of how much difference there is between them.?

The transistor is configured in a DC circuit and is dissipating 767mw continuously in the test. I should have put that in the PDF file but I forgot to.

Tony
AD0VC
-- 
Paul -- AI7JR
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