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Re: FS : OT telescope for optical QRP?
¿ªÔÆÌåÓýHello, Jim and the group-- My apologies for not posting a "spoken for" note for the lens. On a related note, are lens assemblies salvaged from castoff slide projectors of any value to QRP-optical? These often turn up at yard sales. 73-- Brad? AA1IP |
QCX transmit power question
#qcx20mini
#qcx40
#qcxmini
#qcx-mini
#transmitpower
What kind of amperage draw am I supposed to have for transmit on 20 and 40 meters?
-- Wayne S. KF7RCM |
I have several of the Drok buck-boost 12V output converters.
They are 9-36V in for 12V stable out.? I have the 5A units.? I never use them at more than 60% of max current. So far they have not failed and keep the gear I use operating smoothly. FYI the ones on amazon are those I have and look at the reviews carefully, example, running a roof fan with one seems a bad match Look at the images as the aluminum case is not shown but the plastic case 3A unit is.? Like I said read the comments. Picture is the ones I have and use. ------- Allison ------------------ Post online only,? direct email will go to a bit bucket. |
QDX Rev.5 Hi freq bands low power 15m
Hi all,
Last week I built the QDX Hi feq. Version? 5 for 20m, 17m, 15m, 12m, 10m. Blue/ yellow toroids. At 12V. On all frequencies I get more than 4w output, except 15m/ 21Mhz. on a? 50 Ohm dummy load. There I got 0,2w output? and BS170 are getting :very hot. I reworked soldering and checked all components arround L3 and L8. With Putty I found the only difference with for example the 17M is the use of the BPF.? Which components/connections should I control? to make 15m also working? ? HELP WANTED! Btw: On 10m I worked on 10 m FT8 USA stations with my short Endfed antenna!!! So the system works. Rob PA0RBL |
Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
JZ, Tony is saying that the frequency where the peak is expected is off, not the impedance measurement is off. |
Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
I'm not sure if this is the same with QDX, but QMX's 6-layer board, assuming FR4, can have about 25pF per square centimeter on an inner layer if sandwiched by ground or supply planes (13pF if on the outer layer with air on top). So, there are small caps everywhere. |
Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
Tony, I have never tested my NanoVNA to figure out the range of impedance measurements it is good for. I'm sure there is a limit somewhere but where? JZ On Sun, Oct 22, 2023, 12:29 PM Ryuji Suzuki AB1WX <ab1wx@...> wrote:
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Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
Completely speculative here, but winding capacitance, the leakage inductance or both may be affecting the apparent input impedance you measure. Can you add a 10pF or 22pF or something in parallel to the input terminal and see the same phenomenon happens only more distant from the LO freq? |
Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
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From: [email protected] <[email protected]> on behalf of John Z <jdzbrozek@...>
Sent: Sunday, October 22, 2023 10:11 AM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QDXH Tayloe Zin sweep 14074 Mhz #experimental #qdx #qmx ?
Tony,
Might the next few data points have taken the NanoVNA above its range?
JZ
On Sun, Oct 22, 2023, 11:55 AM mux_folder2001 <canthony15@...> wrote:
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Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
Tony, Might the next few data points have taken the NanoVNA above its range? JZ On Sun, Oct 22, 2023, 11:55 AM mux_folder2001 <canthony15@...> wrote:
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Re: FS : OT telescope for optical QRP?
Photo? 73 Jim N6OTQ On Tue, Oct 10, 2023 at 7:49?PM Brad Thompson <brad.thompsonaa1ip@...> wrote:
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Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
¿ªÔÆÌåÓý
I do not understand why the impedance is peaking at 28052. I checked the LO with my GPS locked SDR and it is at 28062 which matches up with a 12KHz IF and being tuned to 28074. I checked the nanovna by sweeping 28074 with a 1KHz bandwidth and it shows up precisely
on frequency on the SDR. So, why is the impedance peak 10KHz below the LO?
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of mux_folder2001 <canthony15@...>
Sent: Saturday, October 21, 2023 1:18 PM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QDXH Tayloe Zin sweep 14074 Mhz #experimental #qdx #qmx ?
28.074MHz with 250Hz resolution.
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of Ryuji Suzuki AB1WX <ab1wx@...>
Sent: Saturday, October 21, 2023 1:12 PM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QDXH Tayloe Zin sweep 14074 Mhz #experimental #qdx #qmx ?
Thanks for your effort. So, 10-12kHz away from the LO frequency the input impedance drops in half on 20m. So, in order not to complicate the IF/baseband signal processing to optimize for the best image rejection, I think it is best to keep the mixer input signal line to a reasonably low level. We still get some of the preselector performance boost but not as much as possible with a direct conversion detector case. |
Re: Assembled QMX Question
Hello Derek Yes! Yes! 73 Hans G0UPL On Sun, Oct 22, 2023, 6:17 PM Derek Brown <dereksbrown@...> wrote: I ordered an assembled QMX with a case.? When it arrives, will it be installed in the case and will it already have the firmware installed? |
Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
Like this, Ryuji:
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Clock at 1 MHz Bandwidth set narrow, 1uF integrating capacitors Ten runs, stepping in 1KHz increments from 990 KHz to 999KHZ Plotting the beat note developing at one of the capacitors. Note the amplitude increasing as the pitch decreases, as Fin => Fclock On Sun, Oct 22, 2023 at 9:22?AM Ryuji Suzuki AB1WX <ab1wx@...> wrote:
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Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
OK Alan! That ties the ribbons on it, I think.
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Thanks for the good info...JZ On Sun, Oct 22, 2023 at 9:51?AM Alan G4ZFQ <alan4alan@...> wrote:
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Re: QDXH Tayloe Zin sweep 14074 Mhz
#experimental
#qdx
#qmx
On 22/10/2023 12:50, John Z wrote:
I read the same thing and come to the opposite conclusion! I take it to mean that truly raw IQ data is conveyed, real baseband data centered about zero, and not data that has been subject to any internal SDR routines, including conversion to a 12KhHz IF.Yes, John. The first firmware kept the 12KHz offset in IQ mode but that was not easy to cope with so Hans removed it. I'm beginning to think straighter, the LO can not appear in the centre of a soundcard sampler. A few good soundcards have virtually no DC spike, maybe what is left is the skirts of the LO or other noise. And yes the LO leakage is low on the QDX but still 60dB above the noise on a local RX. 73 Alan G4ZFQ |