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Re: Power output on 20 meters.
Hi Hans
Thanks for the reply and I did take note of your comments in the manual about accuracy. The problem is that there appears to be a problem on the 20M version and we need some guidance about what do. My simple logic says 5.2 is bigger that 2.2 so there is loss in the LPF. The output should probably be 3.5 watts or so on 20, so if the caps are OK then the problem must be the toroids as the caps and number of windings are "correct" I have removed L1,2 & 3 but I do not have the means to measure the inductance. Please help 73 Mike G0CVZ |
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Re: Power output on 20 meters.
Ben, Joel, all If the power output is less than expected, and if other test equipment is not available, then I suggest removing a turn or two from each of the toroids, similar to what Karsten DL3HRT and others have done.? I think that in the event of the Low Pass Filter having attenuation which reduces the anticipated output, this power has to go *somewhere*... where it is going, is heat. So this is why when you have unwanted attenuation in the Low Pass Filter, people observe heating in the capacitors. 3dB of attenuation at 5W would mean 2.5W lost in the filter, as heat. No wonder, it gets hot... If a capacitor value is too low then this can also alter the shape of the response and cause attenuation at the transmit frequency. Again if you do not have test equipment and you want to be perfectionist, I would suggest just removal of a turn or two or few.? If at any specific supply voltage, one person gets 3.5W, one person gets 4W and another gets 3W, then I think that this is nothing to worry about. In any case many people do not have accurate means of power measurement. If you get 1W when some others get 3, 4 etc., then this is probably an issue (as long as you are confident of your measurement). When measuring power always be aware of the limitations of the instrument! You must use a 50-ohm dummy load because many power meters will not read accurately if you are transmitting into an antenna - any SWR will just alter the measurement. Also do not trust power measurement readings before the Low Pass Filter, the waveform is not a sinewave and many power meters will therefore not read that accurately either.? 73 Hans G0UPL On Thu, Nov 2, 2017 at 4:52 AM, Joel Caulkins <caulktel@...> wrote:
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Re: Power output on 20 meters.
Hi Mike The 9.2 RF Power meter is not bad, but not fantastically accurate. But it is important to realise, this measurement is an RF detector, it will only display a correct power reading for a sinewave into a 50-ohm load. The waveform at L3 is very much NOT a sinewave. The 5.2W measurement is meaningless... 73 Hans G0UPL On Thu, Nov 2, 2017 at 2:23 PM, <mike@...> wrote: Hi All |
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Re: Power output on 20 meters.
Hi All
Results on 20M using 9.2 RF test feature...... Output from L1 with 50 ohm load on output = 2.2 watts approx Input to L3 with 50 ohm load on output = 5.2 watts approx Input voltage on load prior to protection diode = 12.13 volts The caps are the correct values, so I am going to change the toroids one by one. 73 Mike G0CVZ |
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Re: 11. Potentiometer tuning for the Ultimate3
¿ªÔÆÌåÓýHi Hans, I have been analysing this problem by setting my U3S to transmit the Analogue input channels 0-4 & 8 using the MESSAGE menu and TX CW mode. An undocumented feature I found is the actual analogue value is briefly shown on the display while it is being transmitted. Results; With Tn=0 CH0 = 1023 (Band 1 relay) CH1 = 1017 (Switch S2) CH2 =? 925 ¡®Switch S1/TUNE¡¯ pot at max, 511 pot at centre, can¡¯t measure below this as menu runs CH3 = 1023 (Band 5 relay) CH4 = 000 (pin 27) CH8 = wide variation each time (internal temp) but around 290-350. With Tn=1 CH2 = 556 pot in any position. (Menu run not affected). ? BTW, ¡®CW¡¯ mode selected just jams the Tx on immediately and the only way out of this is a full RESET. ? Hope this helps Hans. ? 73 Ken G4APB ? From: [email protected] [mailto:[email protected]] On Behalf Of KENS 2ND ACC via Groups.Io
Sent: 02 November 2017 08:49 To: [email protected] Subject: Re: [QRPLabs] 11. Potentiometer tuning for the Ultimate3 ? Hi Hans, If you get a chance to consider the problems I mentioned earlier, here is some more data; ? If I disable the Tune pot (Tn=0 in menu), and set the tune pot to anything lower than mid setting, the menu runs through as if switch S1 is pressed. How do you programme for this conflict, is there a voltage level at which the A-D input on S1 decides whether it is a switch press or a minimum pot setting? As I said, I measure approx 0.5V on S1 with Tune pot at minimum, and approx 4.5V at max setting, and 2.5V in centre position, so it is seeing less than 2.5V = switch pressed. I would have expected it to see anything above 0.5V as a pot setting only, and below that as a switch press. ? FYI, I replaced the S2 switch with a combo push-pull switch/linear pot so I can still set the menu up, jam it on tx (ptt) for testing, AND have the tune pot all on the QRP labs case front panel. Was a mechanical nightmare to fit (is bigger than your rotary encoder), but looks good now. After so much effort I am keen to get this working. 73 Ken G4APB. ? From: [email protected] [mailto:[email protected]] On Behalf Of KENS 2ND ACC via Groups.Io ? Hi Hans, |
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Re: Toroid winding numbers and measurements
Folks, I Just want to shed light on the effect of spreading or squeezing
windings on inductance of toroids. The Micrometals app note entitled "Iron Powder Cores for High Q Inductors" states: "Another characteristic, which affects the apparent inductance, is leakage inductance. Leakage inductance acts in series with the coils self-inductance. This is a result of uncoupled flux and becomes most apparent in high frequency, low inductance coils particularly when the turns are not evenly distributed around the core. Here is an example where a T50-17 is wound with 10 turns #20 (¦Ì = 4). In cases like this where it is possible to drastically change the positioning of the turns, and the permeability of the core material is low, very large differences are seen. In higher permeability materials this affect is much less. In a number of applications, toroidal coils are tuned by this means. " In the example described for a T50-17 wound with 10 turns, induuctance could be varied from 0.22 microhenries to 0.39 microhenries by simply varying the coil spread from 360 degrees to 120 degrees!! Steve K1RF |
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Re: Toroid winding numbers and measurements
Take an inductor and test it at 100 khz which many cheap testers use. Then do it again with a more costly instrument which more then likely will test at a higher frequency then 100 khz.? This same inductor will read differently.Lee Are you you using a standard, does either of these meters give the correct result? "More costly" does not necessarily mean more accurate. Paul says get an Ebay meter, can anyone recommend one that is definitely accurate? I got one that claimed 1% yet was about 15% when I checked. John makes a good point, we measure the apparent inductance. Stretching/compressing alters capacitance not inductance although the in-circuit effect is much the same. But one of the papers Graham pointed to gives examples of stretching/compressing high frequency low inductance coils changing inductance due to leakage. I'm not sure actual measurements are going to be useful to most QRP Labs constructors. Unless one has accurate standards measurements on ALL meters must be regarded with a degree of suspicion. In practical terms "try removing one turn and observe the effect" is better advice to a beginner than to recommend getting meters of dubious accuracy which might further confuse them. And "remove one (or more) turn and observe the effect" is best done temporally if possible, undo the turns but do not cut the wire until tested. The free loop of wire will not usually have any effect and may be rewound if the desired change in performance is not achieved. 73 Alan G4ZFQ |
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Re: 11. Potentiometer tuning for the Ultimate3
¿ªÔÆÌåÓýHi Hans, If you get a chance to consider the problems I mentioned earlier, here is some more data; ? If I disable the Tune pot (Tn=0 in menu), and set the tune pot to anything lower than mid setting, the menu runs through as if switch S1 is pressed. How do you programme for this conflict, is there a voltage level at which the A-D input on S1 decides whether it is a switch press or a minimum pot setting? As I said, I measure approx 0.5V on S1 with Tune pot at minimum, and approx 4.5V at max setting, and 2.5V in centre position, so it is seeing less than 2.5V = switch pressed. I would have expected it to see anything above 0.5V as a pot setting only, and below that as a switch press. ? FYI, I replaced the S2 switch with a combo push-pull switch/linear pot so I can still set the menu up, jam it on tx (ptt) for testing, AND have the tune pot all on the QRP labs case front panel. Was a mechanical nightmare to fit (is bigger than your rotary encoder), but looks good now. After so much effort I am keen to get this working. 73 Ken G4APB. ? From: [email protected] [mailto:[email protected]] On Behalf Of KENS 2ND ACC via Groups.Io ? Hi Hans, |
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Re: Ultimate 3 Kit Construction
hparkie
¿ªÔÆÌåÓýHello Bob I was sorry to read your e-mail about not having a go at the kit I am 82 and have worn glasses since In was 12 years old Last year I built Softrock transceiver ?using surface mounted components I bought some magnifying glasses on the net and all last winter I had a great time building and testing it, I got it working on receive but not on transmit but who cares I had fun doing it , for this winter I have ordered one of the new kits and am waiting for it to arrive, so have a go at building it you will enjoy it. By the way I am a Plasterer by trade so If I can do it anyone ?can. Good Luck I hope you enjoy it . Hughie G4UMEPS If it does not work you will have had a Winters enjoyment ?out of building it.
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Re: n00b question
Nice to see there are other construction beginners out there OM John. ? |
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Ultimate 3 Kit Construction
Hi there,? I bought the Ultimate 3 kit and the GPS a few months ago. My eyesight is not as good now that I am aged 60 and if I'm honest, I'm not experienced at making kits.? I found someone in the UK who assembled all the circuit boards, but he didn't feel he had the necessary experience to link them up and install them in the supplied case. Does anyone know if there is someone in the UK who could complete this project? Obvious, I am willing to compensate them for their work.? Thanks and 73, Bob Adlington.? M0BOB.? Best wishes, Rob Adlington. -- Sent from Gmail Mobile |
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Re: Band Pass Filters- more bandwidth?
Filter program will verify if the manual is correct.
Assuming the manual is correct then... It's a double tuned circuit with enough coupling for the whole 40m band per the manual.? If both tuned circuits are peaked to the same frequency and the coupling is too loose, it will be more narrow. If it's not covering the whole 40m band, it's likely that the 15pF coupling cap (5+10) is not 15pF. If stagger tune does not get the whole band with reasonable flatness, I'd check the coupling.? Easiest way is to add 5pF and see what happens. 73, -bob ah7i/w4 |
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Re: Toroid winding numbers and measurements
Well the tool we used was certainly ancient, and did not worry about frequency. But, in any case, indeed experimentation may be required. I was trying to do something a bit difficult (getting it to work on both 20m and 30m if C1 is tuned and alignment is done of the other 3 variables) but should not have reduced L4 to just 8 turns, thinking L4 was part of the LPF which I'm less worried about. So I'll restore L4 to proper or close value, and then see if I should change T1 from 31-3-3-3 to 30-4-4-4 as I think the 30m signals are a little down or rather, lacking in volume. I suspect that is due to T1. Before I made those changes, and when I had part of T1 wound or connected opposite direction, the volume was loud, but signals were very heavily attenuated, as would be expected. Just that taking out T1 and putting it back, though this time I have left VERY long legs on the underside of the board, is a headache, I'll have to find a way to label each leg with the correct hole number as I pull it out.
This is indeed a very educational project, now I've learned that frequency does or doesn't really matter too much in the measurement, but especially that cores vary 5 or 10 percent even such small ones so a couple of turns is a possible effect of that variance, and not just the spacing in the winding which is less of an issue. This is really a wonderful project for education and giving a boost to amateur radio, as well as CW. I also look forward to running it as a WSPR beacon, plus hope it will help me into the outdoors and to do a little more exercise, perhaps even contemplate pedestrian mobile. |
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Re: Power output on 20 meters.
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On Nov 1, 2017, at 6:33 PM, Ben Bangerter, K0IKR via Groups.Io <bwbangerter@...> wrote:
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Re: Toroid winding numbers and measurements
Take an inductor and test it at 100 khz which many cheap testers use.? Then do it again with a more costly instrument which more then likely will test at a higher frequency then 100 khz.? This same inductor will read differently.
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Lee, w0vt On 11/1/2017 4:41 PM, Alan G4ZFQ wrote:
PeterYes, a scientific fact.Does this "fact" only apply for iron dust cored inductors because the |
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Re: Toroid winding numbers and measurements
Arv Evans
The "frequency makes a difference" part of measuring inductance of any coil is the distributed capacitance factor.? This apparent difference in measured inductance can be used to calculate the amount of distributed capacitance between windings, but you cannot do anything about it anyway. When I need to make things come out exactly where I want them I usually use a signal generator and oscilloscope to measure the resonance point.
inductance of your coil.? This process includes any distributed capacitance that is inherent in the inductor windings.? I have a variable capacitor that has a dial to show capacitance settings in pf.? With this I can add or subtract capacitance until the inductor resonates at the exact frequency I want.? This helps when working up a new circuit design.? The ancient Heathkit LC analyzer is no more.? It was a very useful tool for doing design work. Arv? K7HKL _._ ? |
Bob ah7i
Joel Caulkins/N6ALT