Re: FS : OT telescope for optical QRP?
Sunday,
October 22, 2023 12:10 PM
Hello, 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
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What kind of amperage draw am I supposed to have for transmit on 20 and 40 meters?
--
Wayne S.
KF7RCM
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Re: Any reason why not this simple answer to not exceed 12VDC
#qdx
#power
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.
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Re: Any reason why not this simple answer to not exceed 12VDC
#qdx
#power
Check the reviews on Amazon, apparently they want to burn themselves up.
--
Wayne S.
KF7RCM
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Re: QDX Rev.5 Hi freq bands low power 15m
ps.: and D2 and D5 polarity is installed correctly?
--
Gyula HA3HZ
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Re: QDX Rev.5 Hi freq bands low power 15m
Rob,
If L7 is not broken (47uH), then also check Q4 BSS123.
--
Gyula HA3HZ
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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
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JZ, Tony is saying that the frequency where the peak is expected is off, not the impedance measurement is off.
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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.
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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: 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?
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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?
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? I don't understand what you are getting at.
TOny
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Tony,
Might the next few data points have taken the NanoVNA above its range?
JZ
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
28.074MHz with 250Hz resolution.
Tony
AD0VC
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.
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Tony, Might the next few data points have taken the NanoVNA above its range?
JZ
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
28.074MHz with 250Hz resolution.
Tony
AD0VC
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.
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Re: FS : OT telescope for optical QRP?
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Hello--
This is a long shot (pun intended), but someone experimenting with
infrared or QRP visual operation
might find the following of interest.
Would someone? be interested in buying a Bausch & Lomb Telescope
and/or
Telephoto Lens model 4000.
It's billed as having a 4" F12 Schmidt
Cassegrain design. This lens comes in a hardshell case
with a custom- cut protective? foam insert. The? documentation consists
of? an
instruction manual and an accessory reference booklet. No other
components are included.
The lens and its case are clean and appear new-old stock condition. I
bought the lens
years ago at an estate sale but never got around to putting it to work.
So it
goes....
If you have any questions please don't hesitate to ask.
I'm asking $25.00 plus USPS postage
Thanks, and 73--
Brad? AA1IP
--
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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
toggle quoted message
Show quoted text
28.074MHz with 250Hz resolution.
Tony
AD0VC
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.
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Re: Assembled QMX Question
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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?
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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?
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Like this, Ryuji:
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
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On Sun, Oct 22, 2023 at 9:22?AM Ryuji Suzuki AB1WX <ab1wx@...> wrote:
Good. Frankly, there's not much else to look for practical purposes. We already have enough clarity in this area.
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OK Alan! That ties the ribbons on it, I think.
Thanks for the good info...JZ
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On Sun, Oct 22, 2023 at 9:51?AM Alan G4ZFQ <alan4alan@...> wrote:
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
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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
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HA3HZ
Ryuji Suzuki AB1WX