Re: DAVE [BITX20] RF Preamp - Attenuator
Began to order and discovered that they want $35 shipping from Hong Kong.? Trying to decide if I want one that bad.?? ...But thanks.
Woody
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On 12/18/2018 4:14, K5ESS wrote: Don't know if they are authentic but you can get them (kind of expensive $6 bucks apiece on Ebay). Also from Kynix for $7.25.
Mike
K5ESS
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Re: DAVE [BITX20] RF Preamp - Attenuator
Thanks for the lead....? Although not too cheap, sure not $250!? Will check it out.? Found a datasheet ( ). It is a pretty bad scan, but maybe enough.
Woody - KZ4AK
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On 12/18/2018 4:14, K5ESS wrote: Don't know if they are authentic but you can get them (kind of expensive $6 bucks apiece on Ebay). Also from Kynix for $7.25.
Mike
K5ESS
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Woody
Sent: Monday, December 17, 2018 8:08 PM
To: [email protected]
Subject: Re: DAVE [BITX20] RF Preamp - Attenuator
Thanks!
Be advised that my AGC amp leaves something to be desired. It works,
but needs refinement. Attack can be slow and it can pump on really
strong signals. Sure wish I had some old Plessey SL621 AGC ICs. Used
one "back in the day"... They were really great for this sort of
application, but they are no longer available.
__W__
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Re: DAVE [BITX20] RF Preamp - Attenuator
Why not take a look at the AD8307.? Seems to be comparable to the SL621.? Different package though.
Regards,
Bruce
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Thank youfor share!
FT'sss73! Renato py2rlm Em ter, 18 de dez de 2018 05:57, giuseppe callipo < ik8yfw@... escreveu:
Hi Ian, I'm Giuseppe, I worked on the small project in stm32f103 based DSP last year, now I'm working on new project based on Cortex M4 processor cheap but performing, and the goal Will be ti creare a monitor with audio controlls like NR variabile filters and other stuff to help and enfatize the audio in rtx home made. Now I'm working on Noise Reduction module and have some results. The DSP tests continue, the Digital Noise Reduction DNR module is ready, in tests the audio signal is taken from a yaesu ft817 sampled at 44kHz and digitally filtered at 12kHz before being processed by the DNR module with Spectral Subtraction technique widely used in modern RTX.?
Next step are the filtering and better user interface ( i use the ic781 theme, simple and fast). When completed I will share It on GitHub.
Best 73 de ik8yfw.
Link1:
Link2:
Link3:
Link4:
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Hi Ian, I'm Giuseppe, I worked on the small project in stm32f103 based DSP last year, now I'm working on new project based on Cortex M4 processor cheap but performing, and the goal Will be ti creare a monitor with audio controlls like NR variabile filters and other stuff to help and enfatize the audio in rtx home made. Now I'm working on Noise Reduction module and have some results. The DSP tests continue, the Digital Noise Reduction DNR module is ready, in tests the audio signal is taken from a yaesu ft817 sampled at 44kHz and digitally filtered at 12kHz before being processed by the DNR module with Spectral Subtraction technique widely used in modern RTX.?
Next step are the filtering and better user interface ( i use the ic781 theme, simple and fast). When completed I will share It on GitHub.
Best 73 de ik8yfw.
Link1:
Link2:
Link3:
Link4:
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Re: Laser cut ubitx case SVG
It took all day but I made my case out of a dry marker
board I got at Lowe's.Used the Harbor Freight multipurpose
vibrating tool to cut the pieces. For the mounting base,
I used a 6X8 wooden photo base I got at Walmart. It all
cost less than $10 but used screws from a Harbor Freight
sheet metal screw kit I already had. Looks OK.
Front panel was once part of a toaster. Used a nibbler to
make the cuts. Took some time but with my tool and die
experience in 1968, it turned out OK Ha
Now experiencing the lack of AGC listening to a group on
160M. Since I'm using a computer speaker in the 'phone
jack, wonder if I put a couple of back-to-back diodes across
the audio line with a 20 Ohm resistor in series to avoid it
looking like a short on the audio line. the level is so low it
might work. (I think) May try it...
Bob ¡ª KK5R
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On Mon, 12/17/18, Robert Sears <kf7vop@...> wrote: Subject: Re: [BITX20] Laser cut ubitx case SVG To: [email protected] Date: Monday, December 17, 2018, 11:42 PM Very nice, I am going to cut one out of acrylic at the local makerspace. Depending on how long it takes (laser cutters are not free to use) I might make a few extras if anyone is intrested
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Re: Laser cut ubitx case SVG
Very nice, I am going to cut one out of acrylic at the local makerspace.
Depending on how long it takes (laser cutters are not free to use) I might make a few extras if anyone is intrested
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Re: DAVE [BITX20] RF Preamp - Attenuator
Don't know if they are authentic but you can get them (kind of expensive $6 bucks apiece on Ebay). Also from Kynix for $7.25.
Mike
K5ESS
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Woody Sent: Monday, December 17, 2018 8:08 PM To: [email protected]Subject: Re: DAVE [BITX20] RF Preamp - Attenuator Thanks! Be advised that my AGC amp leaves something to be desired. It works, but needs refinement. Attack can be slow and it can pump on really strong signals. Sure wish I had some old Plessey SL621 AGC ICs. Used one "back in the day"... They were really great for this sort of application, but they are no longer available. __W__ On 12/18/2018 1:48, Dave Space wrote: On Mon, Dec 17, 2018 at 03:28 PM, Woody wrote:
www.albe24.com
Thanks, wow you have quite a lot of home brew builds! Very nice.
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Re: DAVE [BITX20] RF Preamp - Attenuator
Thanks!
Be advised that my AGC amp leaves something to be desired.? It works, but needs refinement.? Attack can be slow and it can pump on really strong signals.? Sure wish I had some old Plessey SL621 AGC ICs.? Used one "back in the day"...? They were really great for this sort of application, but they are no longer available.
__W__
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On 12/18/2018 1:48, Dave Space wrote: On Mon, Dec 17, 2018 at 03:28 PM, Woody wrote:
www.albe24.com
Thanks, wow you have quite a lot of home brew builds!? Very nice.
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Re: DAVE [BITX20] RF Preamp - Attenuator
On Mon, Dec 17, 2018 at 03:28 PM, Woody wrote:
www.albe24.com
Thanks, wow you have quite a lot of home brew builds!? Very nice.
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Re: No audio from last week may have a solution
Sean
Glad you may have found it. Sure, bridge any similar value cap you have. You can even temporarily,? or permanently install the leaded cap on top to see if audio is restored.
I have certainly used leaded parts on surface mount boards, its nothing to fret about.
BTW smt caps when you have them tend to be easy to install with their higher mass than many other parts. But use what you have, and enjoy the radio. Good eyes in your discovery.
Curt
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Re: No audio from last week may have a solution
Hi Sean,
It's no problem to use a conventional part with leads if you want.? You'd just have to be careful that the connections don't stray onto other pads.? If you have room, you can just tape the part down near pads, then push the leads down onto the pads, clip off the excess and then solder.
73,
Mark.
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Re: No audio from last week may have a solution
Take two 15-30 watt irons . Heat them both . Hold one om each hand. Place tip of one on one end of part place the tip of the other on the other end of part. Slightly press the tips together and when solder melts lift part off the board. Clean up pads with solder braid. Get some paste flux and put a small amount on the pads.Using tweezers place the new part on pads. Put a small blob of solder on tip of iron place tip on one end of part and pad at the same time (hold the part in place with a small screw driver until solder flows. Repeat exactly for other side of part.
I used this method several times a day for 10 years while working as a repair tech in a manufacturing company.
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Re: DAVE_2a [BITX20] RF Preamp - Attenuator
The PDF is of what the etched board looks like.? For most PC board generation, the image must be flipped to reverse. _W_ On 12/17/2018 23:38, Woody wrote: Dave,
It occurred to me that the to-scale PDF of the preamp/filter board and parts layout are not in the zip file.
Those are attached...
Woody
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Re: oh, and it's a 4 transistor AGC board
John
I just assembled the simpler nd6t agc, one npn plus one mosfet. I left room on the board to update it to the other circuit. The first 20 dB may be enough as I am used to the k2 limited agc. I can't get it installed for a couple weeks. Yes lets trade notes.
Curt wb8yyy
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Re: DAVE_2[BITX20] RF Preamp - Attenuator
Dave,
It occurred to me that the to-scale PDF of the preamp/filter board and parts layout are not in the zip file.
Those are attached...
Woody
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On 12/17/2018 16:06, Dave Space wrote: Hi do you have the files for the RF pre-am and the agc?
Hard to see the pic there do the files specify exactly where the connections go to the main board?
Thanks
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Re: DAVE [BITX20] RF Preamp - Attenuator
Hi Dave,
I think all (more than?) you want to know can be found on my web site,? www.albe24.com
Need to scroll down and click on the Amateur Radio section, then to the uBitX.
The thumbnail image is a link to a ZIP file with the most pertinent information on my build.? It is about a 4 meg file.
The direct link is:? www.albe24.com/kz4akubitx.zip
Hope this helps.? I think everything is now accurate!? Let me know if more info needed.
Woody
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On 12/17/2018 16:06, Dave Space wrote: Hi do you have the files for the RF pre-am and the agc?
Hard to see the pic there do the files specify exactly where the connections go to the main board?
Thanks
_._,_._,_
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No audio from last week may have a solution
So last week I said that there was an audio hiss, but no signal on my UBitx v4. I think I may have traced the problem. The capacitor C4 seems to have been mechanically scraped off the board. My surface mounting skills are not up to much. Am I best trying to bridge it with a conventional 100 nf capacitor, try to get some surface mount or get a replacement board.
What are the vendor like at sending out replacement boards? Any idea how much the board would be?
Best wishes
Sean 2e0sfq
Sent from my Huawei Mobile
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Re: Reasonable cost Spectrum Analyzer for Ham use.
#ubitx
Possibly for some less expensive alternatives can see this message chain
https://www.eham.net/ehamforum/smf/index.php/topic,123052.0.html
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oh, and it's a 4 transistor AGC board
...that I'm looking for instructions/diagram on installing.
Looks like there's at least a couple versions.
Thanks John K5MO
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Bob Lunsford
