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Re: The new uBITX boards are here
For use around the house, I plugged in a pair of old computer speakers I was not using.? While only one of them puts out sound as is (stereo speakers), it sounds very good.? The amp in the speaker helps boost the sound level.? On Mon, Jun 4, 2018 at 5:04 PM, Arv Evans <arvid.evans@...> wrote:
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Re: RF power chain mods and improvements..
The significant spur is generated in the last mixer where 45mhz IF on one port, 73mhz lo,
and the signal at 28mhz out plus 17mhz spur.? The spur at low levels tracks both the tuning? and the drive level, no drive no significant signal (in the Spec-A? noise about -100DBM). The other is a side result of 11.995(+-) leaking.? That guy is there but very weak and well below the level of concern. Allison |
Bo Barry
On eBay from Kansas.? It's the 2.8" enhanced model with RTC and GPIO
. He has a direct sales site too. If you plan to order one before July 31st drop me an email and I'll give you the company link and code for a 5% discount! 73, Bo W4GHV since '54 my Gmail is the same as my Novice call in '54 WN4GHV? (to make it long enough for Gmail) |
Re: Github's future?
There are several other on-line version-control systems.? Some are free and others charge high prices for their use.? Some have potential for BITX code development work, and some less appropriate.? Those of us using Linux already have local RCS and VCS that was migrated from ancient UNIX tools.? CVCS (Concurrent Version Control System) is also available on Linux systems. Some of the readily available IDE packages also include either RCS or CVS tools.? Of course these are local solutions, but they could be made accessible to others via a shared file system on cloud-computing servers. If the Microsoft purchase of GitHub does become a problem then we might want to look at some of these alternatives.? It might be interesting to approach the people who made and support to see if they could include some sort of version control as an option for groups that are interesting in code development.. Arv _._ On Mon, Jun 4, 2018 at 10:34 AM Joel Caulkins <caulktel@...> wrote: This can't be good:-( |
Re: RF power chain mods and improvements..
>>For my tests I inserted 1KHz at variable levels and adjusted the audio level for?
cleanest RF on the oscilloscope.? Then I performed a frequency sweep to look for? spurs.? As long as the microphone port audio input is below 45 millivolts the spurs seem?
to be down at least 50db, but can be pushed even further down by reducing the audio?
level to around 32 millivolts.? This seems to be where oscilloscope peak-to-peak RF level? is about the same as when using CW mode.??<<< What was the power out on 10M? The actual input I was using was such that full up was 150mv P-P (about 100mV rms) and usually lower at 70mvPP (50mVrms). Adding a band pass filter for 10m helped.? at 80/40/20m there were no significant spurs, save for harmonics about 50 db down. Allison |
Re: RF power chain mods and improvements..
Ralph,? What was the line up of mods.
The spur is not a linearity issue its just there. I inserted a band pass filter haywired in at 28Mhz and though sloppy the spur was? suppressed an additional 20DB (-73dbc).? That was with most of my mods at 8W and the input level driven to 80M max levels. Generally the amp has been reasonably linear, just hurting for gain from about 8mhz to 28mhz.? Allison |
Re: RF power chain mods and improvements..
Allison is correct that things are much cleaner when using CW.? For my tests I inserted 1KHz at variable levels and adjusted the audio level for cleanest RF on the oscilloscope.? Then I performed a frequency sweep to look for spurs.? As long as the microphone port audio input is below 45 millivolts the spurs seem to be down at least 50db, but can be pushed even further down by reducing the audio level to around 32 millivolts.? This seems to be where oscilloscope peak-to-peak RF level is about the same as when using CW mode.? I could not duplicate this using an averaging type RF voltmeter as the signal level detector. It is interesting to vary the microphone port input frequency and watch each spur to see if it moves up or down.? This could be an aid in figuring out how each spur is being generated.? Arv _._ Arv _._ On Mon, Jun 4, 2018 at 10:32 AM Howard Fidel <sonic1@...> wrote:
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Re: Nextion Display
Bo ?
I know exactly what you are talking about but I now feel like I am making some progress. I hope Dr. Ian makes some of his work with the Nextion ?available to us soon. I liked your last sentence, I sometimes feel like I had more free time before I retired than I do now.? 73's ?kn4ud ? -- Allen ?Merrell |
Re: The new uBITX boards are here
Jamie It depends...on how you will be using your BITX.? For CW only your speaker might be good if its response peaks at around 700 Hz.? For SSB only you might like a speaker that has a "communications passband" of between 200 and 3200 Hz.? Amateur radio does not require full bandwidth high-fidelity sound.? Almost any small speaker will work.? The acoustic characteristics of the speaker housing is usually more important than the speaker specification.? Audio amplifier IC's usually use some sort of push-pull or totem-pole output stage and thus will match from 4 ohms upward to 100 ohms.? Audio output power is usually dependent on speaker impedance.? Lower impedance works the audio amplifier harder and delivers more audio output.? It helps to look up the datasheet specification for the particular AF output device to see what it says is best for impedance match and for maximum output at specific impedances. Arv? K7HKL _._ On Mon, Jun 4, 2018 at 10:24 AM Jamie Anderson <jamiea@...> wrote: I ordered a kit a few weeks ago and think I will be receiving the board with the updated discreet audio amp.? Somewhere I thought I saw that a 32 ohm speaker would be the best fit for this amp, but can't find this post anymore.? What is the best impedance and what is the approximate power out?? |
Re: RF power chain mods and improvements..
I don't recall the exact amount of power out but it was greater than 6 1/2 watts out. My thinking is that if I put in a 1000 hz tone in the mic input and wound it up to the maximum and backed off a db or so? whatever stage was saturating would come out of saturation and be more or less linear. This was after being in the CW mode that I used the pot on the ubitx board to get the maximum out and backed it off some to where the power just started? to fall off. On Mon, Jun 4, 2018 at 3:47 PM, Tim Gorman <tgorman2@...> wrote: When the power starts to fall off you are still putting out 8 watts |
Re: RF power chain mods and improvements..
When the power starts to fall off you are still putting out 8 watts
with the 1000 hz tone? tim ab0wr On Mon, 4 Jun 2018 13:04:33 -0400 "Ralph Mowery" <rmowery42@...> wrote: Using a HP 8924c in the SA mode I do not seem to be seeing any of the |
Re: Building homebrew ubitx: Need pre-v3 schematic PDF. Also, source for 45M15 (45 MHz IF) filter?
I believe this is the original uBitx schematic:? ?
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In this post:??/g/BITX20/message/33203 Farhan explains that the 45mhz filter must be narrow enough to reject signals 2 mhz away from center. I believe he is using the 45m15a, which is probably 15 khz wide with two poles. But most anything 45mhz with 2 or 4 poles will work. Bandwidth of available filters varies from 7.5 khz to 30khz, this shouldn't matter much either.? A search for "45 mhz crystal filter two pole" finds this throughole part, in stock at Mouser: ? ??ECS ECS-45K20A I'd guess that will work fine. Most such crystal filters are now surface mount. Those would work too, but may be harder to hack into an existing PC board. I don't think I would bother with creating a new board. ? ?? Perhaps a more serious issue for you is that the old uBitx schematic only shows two low pass filters after the IRF510's.? These did not sufficiently attenuate the second harmonic. The current design has four low pass filters there.?? If all you have is two LPF's, I suggest you stuff them for your favorite two bands. Lower bands could be supported by adding an appropriate LPF stolen from the current uBitx design in line with your antenna coax.? Of course, whichever of the two LPF's inside the rig that you select, nothing higher than that will get out to the antenna port.? ? I suggest stuffing LPF's for 20 and 40 meters (also covering 17m and 30m, respectively), use an external LPF for 80m. Give anything above 17m a pass for now, as those bands are a bit problematic. Power out can be down under a watt on those high bands, and we can have an out of band spur when transmitting.? Those issues are still being resolved. Jerry, KE7ER ? On Mon, Jun 4, 2018 at 11:32 am, David Feldman wrote:
This posting contains two questions: |
Re: Correct levels from computer to uBitx in digimodes
I used my DS202 pocket scope, $99 Amazon, to read the output from the stock mic into the radio while saying aaahhhh at a normal volume. Then installed a SSM2167 board with a 10k potentiometer on the output and adjusted it for about 125% of the previous reading.? That little scope works great for audio levels.? It's cute too.
-- Lee - N9LO? "I Void Warranties" ? |
Re: Building homebrew ubitx: Need pre-v3 schematic PDF. Also, source for 45M15 (45 MHz IF) filter?
The same schematic works for both. I will send you the LC filter details if you need them. The 45 mhz filters are regularly available on ebay. - f On 5 Jun 2018 12:02 am, "David Feldman via Groups.Io" <wb0gaz=[email protected]> wrote: This posting contains two questions: |
Building homebrew ubitx: Need pre-v3 schematic PDF. Also, source for 45M15 (45 MHz IF) filter?
This posting contains two questions:
I am building a homebrew version of ubitx (on PCB layout I created myself). PCB was manufactured a year ago, but did not start bringing up circuit at that time. Since about 2 weeks ago, I have been bringing up the receive path first (along with necessary microcontroller and synthesizer stages), one stage at a time, beginning with the loudspeaker, and so far having good results and fun experience. I realize now (that I am at the 45 MHz IF filter, heading towards the first mixer) that I did not save schematic I used to create PCB, and v3 schematic (more recent) includes a part (the 45 MHz crystal filter) I did not find in the version I based my PCB layout on. I understand the benefit of the filter, however, I wish to continue progress on my PCB based on older design, as I will gather changes (including use of the newer IF filter design) for a future PCB rev. My PCB layout assumed multi-pole LC filter from the schematic I had available at the time (original or maybe v2, but not v3 or later). In this version, the 45M15(A? B? F?) filter was not included, and it is not present on my PCB layout. So, I have two questions: 1. What is URL or other way to find version of ubitx based on LC filter in 45 MHz path? 2. Where is current source for the 45M15 (A? B? F?) filter used in V3 and later designs? I did not find it in search on US distributors nor on ebay; I understand these should be low cost part with good availability, so I think I am not looking in right place? Thank you, and this is very enjoyable project! 73 Dave WB0GAZ wb0gaz@... |
Re: Correct levels from computer to uBitx in digimodes
Joe Puma
¿ªÔÆÌåÓýWhen I hooked my bitx40 to my computer I adjusted audio coming out of the computer ?using the volume in computer mixer and monitoring on another radio. For wsjtx I used the waterfall as a visual aid and the radios volume knob to adjust audio into computer.?This worked well. There is room to play but looking how other applications join a radio with a computer like when making a AllStar node and wiring up speaker and Mic to a computer people put resistors in place to bring the levels down. Like 68k ohms on the radio audio out. Taken before the volume pot so the pot is not controlling the volume. And 10k ohms on the Mic in on radio.? Here¡¯s the example I am talking about.? What I found that might be more useful instead of worrying about signal levels is hooking the radio up so it¡¯s not electrically connected by using some 1:1 transformers. I found that with using my 100w radio and long audio wires your setup might be susceptible to RF getting in the wires. ?I have an issue on 40 meters with RF getting in my audio if I use my powered mic or long extension wires on my Mic cable. Ferrite beads don¡¯t seem to solve the problems.? Joe Kd2nfc? On Jun 4, 2018, at 10:02 AM, Jan Brink <janbrink@...> wrote:
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Re: Nextion Display
Jack
Thanks for the reply, LOL, I have the book and I need to dig it out and get back into it again. The work you and AL did is fantastic. I just hope to get a similar result with less options on a smaller display. The filter part I am just not going to try programming that I am going to cheat and use a Sotabeam adjustable that I have this will cure filter and audio amp all in one package but just won't ?be on the screen. 73's ?kn4ud ? -- Allen ?Merrell |
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