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Re: Calibration & filters
#calibration
#filters
I specify, I am currently working with a 12mhz SSB filter
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Re: Calibration & filters
#calibration
#filters
Hello,
a little code reading before my question on value of frequencies Code UBITX V4.3 The uBITX is an upconnversion transceiver. The first IF is at 45 MHz.
? ?The first IF frequency is not exactly at 45 Mhz but about 5 khz lower,
? ?this shift is due to the loading on the 45 Mhz crystal filter by the matching
? ?L-network used on it's either sides.
? ?The first oscillator works between 48 Mhz and 75 MHz. The signal is subtracted
? ?from the first oscillator to arriive at 45 Mhz IF. Thus, it is inverted : LSB becomes USB
? ?and USB becomes LSB.
? ?The second IF of 12 Mhz has a ladder crystal filter. If a second oscillator is used at
? ?57 Mhz, the signal is subtracted FROM the oscillator, inverting a second time, and arrives
? ?at the 12 Mhz ladder filter thus doouble inversion, keeps the sidebands as they originally were.
? ?If the second oscillator is at 33 Mhz, the oscilaltor is subtracated from the signal,
? ?thus keeping the signal's sidebands inverted. The USB will become LSB.
? ?We use this technique to switch sidebands. This is to avoid placing the lsbCarrier close to
? ?12 MHz where its fifth harmonic beats with the arduino's 16 Mhz oscillator's fourth harmonic
*/
// the second oscillator should ideally be at 57 MHz, however, the crystal filter's center frequency // is shifted down a little due to the loading from the impedance matching L-networks on either sides
#define SECOND_OSC_USB (56995000l)
#define SECOND_OSC_LSB (32995000l)
?
?
//these are the two default USB and LSB frequencies. The best frequencies depend upon your individual taste and filter shape
#define INIT_USB_FREQ? ?(11998370l) ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Code KD8CEC ..... ?#define SECOND_OSC_USB (57003400l)
? #define SECOND_OSC_LSB (33010400l)?
? //these are the two default USB and LSB frequencies. The best frequencies depend upon your individual taste and filter shape
? //Not used, Just comment (Default)
? #define INIT_USB_FREQ? ?(11996500l)
....MY TESTS: I made a model to test my 45MHZ filter with a nanovna (So i change the value of inductance and capacitors for maching (1.5 ?h and 8pf) on my homebrew assembly))
this gives:
Central frequency: 45.004280 MHZ
Low frequency at -3DB: 44.997900 MHZ approximately
High frequency at -3DB: 45.010480 MHZ approximately
My question:
function of the values (which are different) in the code v4.3 of the Ubitx and KD8CEC? and my filter frequencies description , what would be the 3 best values for USB freq, OSC USB and OSC LSB knowing that a priori they take into account matching ? I would like to amend the code to that effect cdt |
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Re: Need replacement Raspberry Pi image
John,
if I may suggest, I would check the connection of the RPi4 and the digital module in your device. Or I pull it out and plug it back in. Maybe it fell apart during shipping? Just a hint. I don't have an sBitx, but I will monitor the developments and check on an RPi400. I'm getting to know Raspberry until I get to it. The point is that without hardware, the sBitx frame just flashes and disappears, although it does not freeze. The image contains many options. Among them, it also recognizes the usb connection formatted for ntfs (I tried with a usb stick). It has a scrot screenshot maker, but I put the GNOME screenshot because it comes up with the graphic window and I can call it up with a hot key. I'm still getting to know the system. Oh, and I google a lot. All logs found in directory : /var/log/ -- Gyula HA3HZ |
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Re: Raspberry Pi image for sBitx -- where to download?
On Fri, Sep 23, 2022 at 06:46 PM, Max wrote:
Use IDM Internet Download Manager or IDM Integration Module in your browser. There is probably another download manager that can resume the interrupted download. -- Gyula HA3HZ |
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Re: sBITX USB ro HDMI
#sBitx
Someone please correct me if I¡¯m in error but I don¡¯t think it¡¯s feasible to send a video feed from a raspberry pi to a monitor. That¡¯s why there are two different types of connectors on the raspberry pi in addition to the USB ports.
I cut a hole near the back of the case. It¡¯s made of aluminum so it was quick work with a drill and a Dremel. |
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Re: day light again `inquiry
But where do you find N750 capacitors?? New availability is close to non-existent, and supplies on eBay are limited. Temperature compensation in commercial gear is a lost art. Nobody uses VFOs any more,?and so there is little demand for?N750 or other capacitors with?specified?temperature coefficients other?than NP0.. And the really good compensated?VFOs had to be individually tuned, which is anathema to the notion of automated mass production. On Fri, Sep 23, 2022 at 5:34 PM ajparent1/kb1gmx <kb1gmx@...> wrote: That's pretty slick, nice build. |
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Re: day light again `inquiry
Allison, here is a pix of my PTO. The limited coverage is FB for my needs. This is going to be a CW rig and not SSB. Stability of this PTO from a cold start is about 60hz. I used a combination of polystyrene, NP0 and N750 caps. Tuning range covers close to 160khz with the 10-32 screw and the amount of L end C I am using. I will look at my filter and spectrum of the PTO when I get some time this weekend. Thank you for your suggestions! 73 Barry On Fri, Sep 23, 2022, 2:13 PM ajparent1/kb1gmx <kb1gmx@...> wrote: Since it tunes in parallel, my SWAG is VFO (has spurious oscilation) or |
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Re: Raspberry Pi image for sBitx -- where to download?
¿ªÔÆÌåÓýThanks. One of the first things I did when I received the unit was to archive the image, which I found and am using now.On Sep 23, 2022, at 11:18 AM, KB3UUL <v319554@...> wrote:
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Re: Need replacement Raspberry Pi image
I had previously copied the original image on the SD card. I found it and burned it onto another 32GB micro SD card. |
Gerard
W6LKB
HA3HZ
John Terrell, N6LN
Shirley Dulcey KE1L
