Question : uBITX V5 - AGC + CW Filter #v5
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uBITX V5 - AGC + CW Filter
I am buiding up my uBITX V5 Additional I've the - AGC Kit from Kit-Projects V1.0 especially for uBITX - CW Filter from SOTABeams Appling the AGC is clear - on the VOL potentiomenter. Now the CW-Filter: the uBITX has already a LM386 amplifier. The CW Filter has a differencial AF Output. AF input is single. Should I connect the CW Filter after the existing AF Amplifier LM386 or where? 1. before the in build LM386 - then I loose the differential output from CW Filter 2. after the in build LM386 - then I miss the final Amplifier for eg a speaker..must appl a external one. 3. changing the build in LM386 so that I am able to connect the differecial to them ? Has anybody expirience with such a constellation ? Any Ideas are welcome Erich -- --- 73 de Erich HB9FIH HS0ZLS
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When I tried to add that filter I ended up at the same cross roads as you. What I ended up doing was adding a nescaf and turned the sota beams filter into a stand alone with a class d audio amp. I tried to add it to the uBitx but found adding another amp was just a bad mix 2x volume knobs etc. I know its not the answer you are looking for but its what I ended with. If you do go that route of making it a stand alone I have one sota beams prototype break out board left that I would be happy to send for cost of shipping. https://www.youtube.com/watch?v=6HwSCTcr_sg https://www.youtube.com/watch?v=bL9VZcpNPaA
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Curt
I integrated a nescaf into my v4 -- very cool to have a bandwidth knob on the front panel. it works nicely. v4 does not use a lm386 but a weaker audio amplifier - so its a nice boost for a v4. the nescaf has a pot on the board to adjust its own net gain - so it can work with any single ended input.
For AGC i have a homebrew VK3YE AGC mounted onto the volume control - no board mods required. it nicely squashed the very loud signals, and I have it feeding a meter to get some action on the front panel. I can also see the glow of the LED from this circuit (even inside the case) as an indication of signal strength. 73 curt
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TNX Curt, tnx David I assumed there is no final solution, but says me I am on the same way. Thats so far ok. Now will think about and maybe do the "try" method... I know the NSCAF - have a DIY done. Will then report what I've done. But the instruction does match whats happend ....so try to find out.. 73 Erich btw I am at my sailing ship shack (it's also an electronic HAM laboratory) - QTH this time Island Samos in Aegean sea.
HB9FIH HS0ZLS
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Evan Hand
Eric,
I have not added the filter. I have added an external amp to a v5 board. I found that I needed to reduce the gain of the LM386 to reduce the potential to get feedback. The LM386 as onfigured in the stock v5/6 has the gain set to 200. By removing the feedback capacitor C75 from pins 1 and 8 of the LM386 the gain is reduced to 20, which is much better for the external amp. I did it as a test by bending the pins up so that they did not go in the socket. I also added a "base bost" by soldering onto the LM386 with an RC feedback from pin 5 to pin 1 as in the attached picture. The resistor is 10k and the cap is 0.47uf. There is another way of doing this based on the datasheet from National Semiconductor: To add a 1.2k resistor and 10uf cap between pins 1 and 8. I have not tried that choice and do not know what the gain would be using that approach. The result for me was a reduction in the static "hiss" and as I stated before more stable operation of the add audio amp. 73 Evan AC9TU
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Was this new/old stock NEScaf or have you run across a source? They look cool. Ted K3RTA
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They were selling them again but looks like they are sold out. https://www.newenglandqrp.org/nescaf/
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dave
mouser is still selling the scaf chip LTC1060 in a dip version for around $10 for the cn flavor. Looking briefly at the data sheet I did not see what the difference was between the cn and the acn.
my first scaf implementation was on a wire wrap board. building it is straight forward. dave /nt1u
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Richard Spohn
The notice about being sold out has been up there for more than a year. I really REALLY want 2 NESCAFs but at this point, I doubt that I will ever see one...Rich WB2GXM Sent from my MetroPCS 4G LTE Android device
------ Original message------ From: N8DAH Date: Wed, Oct 21, 2020 6:51 PM To: BITX20@groups.io; Cc: Subject:Re: [BITX20] Question : uBITX V5 - AGC + CW Filter #v5 They were selling them again but looks like they are sold out. https://www.newenglandqrp.org/nescaf/
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Thanks, David. Keepimg an eye out there. Good site.
Dave, Tnx for the parts lead. What's cn & acn designate, country of origin? -Ted
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We can't hold a kitting party under the current circumstances, which is now the NESCAF kits were normally assembled. It would have to be a solo effort. The price would have to go up a bit because of postal rate increases.
On Wed, Oct 21, 2020 at 8:40 PM Richard Spohn <wb2gxm@...> wrote:
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barry halterman
Try the Maxim, max7400 chip. There is a post on this group showing a simple schematic of its use. I built one for each of my ubitx rigs and they work very good.
Thanks, David. Keepimg an eye out there. Good site.
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Richard Spohn
Ok Shirley, thanks. Don't care if the price goes up! I want my NESCAFs!!! I will pay! Please, please email me about how to get 2 kits!!!!--Rich WB2GXM Sent from my MetroPCS 4G LTE Android device
------ Original message------ From: Shirley Dulcey KE1L Date: Wed, Oct 21, 2020 8:47 PM To: BITX20@groups.io; Cc: Subject:Re: [BITX20] Question : uBITX V5 - AGC + CW Filter #v5 We can't hold a kitting party under the current circumstances, which is now the NESCAF kits were normally assembled. It would have to be a solo effort. The price would have to go up a bit because of postal rate increases. On Wed, Oct 21, 2020 at 8:40 PM Richard Spohn <wb2gxm@...> wrote:
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The difference between the LTC1060 and the LTC1060A is that the A version has a tighter specification for the relationship between the clock frequency and the center frequency of the filter. In the NESCAF you're using a pot to adjust the frequency, so there is no need for the tighter-spec part. The New England QRP Club still has some circuit boards and some of the components to make additional kits. We don't have more LTC1060 chips or the other expensive components. I'll see if anybody in the club is interested in making another batch of kits happen. I suspect the days of the LTC1060 in DIP are numbered. The LMF100 was discontinued altogether, and the MF10 in DIP returned for a bit but is now gone again. The next batch of kits, when it happens, is likely to be the final one. A bit of history: the kit originally used the MF10. That was replaced by the LMF100, an improved but pin-compatible chip. Later it switched to the LTC1060 (another pin-compatible chip, comparable in performance to the LMF100) when the LMF100 in DIP was discontinued. I have the first NESCAF with an LTC1060, built with a sample chip from Linear Technology.
On Wed, Oct 21, 2020 at 8:51 PM barry halterman <kthreebo@...> wrote:
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