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Re: Standoff question
¿ªÔÆÌåÓýSome of us are retired with nothing to do! Well, at 72 years old, the gal friend bitched so much, I had to buy a lawnmower ( and yes, I paid for it) and mow and weedwack the lawn today! Now, I can go back to BitXing! And we are too Old for "LOL" or Texting!
Mike, WA6ISP
On 10/19/2017 3:55 PM, John P wrote:
It's so nice to have too much time on your hands! ?LOL!? -- Mike Hagen, WA6ISP 10917 Bryant Street Yucaipa, Ca. 92399 (909) 918-0058 PayPal ID "MotDog@..." Mike@... |
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Re: [Bitx40] tests on 20 meters rx
I've done some more upgrades to the 45W HF? ($14) Ebay amp, knocking off about a dozen parts and improving the purity overall . I figure the XL primary of the final balun is not matched to the parasitics of the push pull FETs and that's messing with the lower HF purity. Check the logs on the hackaday link in the last msg for the mods and improvements.
Here is the progress so far: -- AncelB, MIT EE6002 |
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Re: More questions
On Thu, Oct 19, 2017 at 02:02 pm, m0wid wrote:
My hack for the carrier pulse was to take the PTT from the mike directly into the Raduino (same input as PTT sense in Allards code but with pull up enabled) and then add code to turn off the clock from the Si5351, output the PTT to the relays, wait 50ms (may be able to reduce this but for SSB is no problem) then turn the clock on again.Dave, thanks for sharing this clever idea to suppress the carrier pulse! I tried it out and even with the standard PTT setup it works great! So it's not necessary to take the PTT from the mike directly into the Raduino as you did. It's just two lines of extra code. I'll include your idea in the next version v1.26, along with some other improvements. To be released soon. Thanks! 73 Allard PE1NWL |
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Re: Standoff question
Thomas Noel
¿ªÔÆÌåÓý1.8?terafurlongs per fortnightCaveats:
1. I am not a degreed mechanical engineer. 2. My meds might not be properly titered. 3. The second paragraph above is my conjecture, unsupported by experience and previously unreviewed by competent authority. 4. Fitness for any specific use is purely coincidental. 5. Use of anything in the commentary above is solely at the risk of the user as it is submitted for its entertainment value, if any and no other use is recommended, authorized, or intended. Thomas Noel kf7rsf
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Re: Standoff question
John P
I bought a bag of 100 1/4" nylon spacers from McMaster-Carr for a couple of bucks. They take a 4-40 screw. I bought them longer than needed and cut them to the required length for whatever I'm using them for. Besides using them for the BitX board, I put spacers between the display and Raduino and have used them on a number of other projects.
-- John - WA2FZW |
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Re: Standoff question
i know that m3 screws fit and i measuree the height with the scale in my tools drawer. For those who insist on metric purity, do the math. Anyone got the speed of light in furlongs per fortnight yet? - f On 20 Oct 2017 2:29 am, "Michael Hagen" <motdog@...> wrote:
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Re: More questions
I have only had my bitx40 for a week but am having lots of fun with it. Great receive audio. My hack for the carrier pulse was to take the PTT from the mike directly into the Raduino (same input as PTT sense in Allards code but with pull up enabled) and then add code to turn off the clock from the Si5351, output the PTT to the relays, wait 50ms (may be able to reduce this but for SSB is no problem) then turn the clock on again. Eliminated the spurious transmission entirely and reduced but not eliminated the pop on the speaker.?
Agc is next hack. Wondering about feeding the 5v PTT out to the relays also into Farhans audio agc circuit via a diode after the diode for rectifying the audio signal. I guess this will turn the fet on effectively shorting the input to the audio amp hopefully before the relays change over. ?The time constant in the agc may also remove the tx-Rx pop. Anyone see any problems with that?
?
Dave M0WID? |
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Re: Standoff question
¿ªÔÆÌåÓýAsh, Hey, you are mixing Metric with our wonderful SAE Imperial sytem! Ha..Ha.. They are 0.427" long. On 10/19/2017 1:47 PM, Ashhar Farhan
wrote:
-- Mike Hagen, WA6ISP 10917 Bryant Street Yucaipa, Ca. 92399 (909) 918-0058 PayPal ID "MotDog@..." Mike@... |
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Re: Standoff question
¿ªÔÆÌåÓýThey are 3mm 0.5 thread.? Metric, and the ones with male stud are not cheap.?? Double female holes are the most common. Mouser or Digikey or surplus vendors would have 4-40 US thread. The distance on the LCD connector is 0.427".? I
make them on the 3D printer and use #4 sheet metal screws.? That
allows the LCD to be parallel. Hole about 0.110" works fine.? I would make them for you, you just do the postage? The printer takes about 15 min, and I make 6-8 at
a time.? They are ABS filament. Mike, WA6ISP
On 10/19/2017 1:21 PM, Barrett O wrote:
Hey guys I'm looking to buy some extra standoffs of about the same size that come with the bitx to mount some buck converters. does anybody know what size the standoffs are? -- Mike Hagen, WA6ISP 10917 Bryant Street Yucaipa, Ca. 92399 (909) 918-0058 PayPal ID "MotDog@..." Mike@... |
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Re: Standoff question
m3 thread on half inch stanoffs - f On 20 Oct 2017 1:51 am, "Barrett O" <ogebarrett@...> wrote: Hey guys I'm looking to buy some extra standoffs of about the same size that come with the bitx to mount some buck converters. does anybody know what size the standoffs are? |
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Re: Would this P/S work?
¿ªÔÆÌåÓýThe LM723 datasheet has some great examples of adding pass
transistors to linear voltage regulators for greater output
current.? I use an LM723 based linear power supply and while it's
inefficient compared to switchers it's quite easy to get clean
power out of them.? Linear or foldback current limiting is also
easily available with the 723. On 10/19/2017 03:44 PM, Dexter N Muir
wrote:
For more current output, try this: |
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Re: Would this P/S work?
LOL! When that IRF-510 overloads and POPs, you're clearly wanting the
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neighbors to know about it, too! HiHi On Thu, 19 Oct 2017, Dexter N Muir wrote:
For more current output, try this: |
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Re: Would this P/S work?
For more current output, try this:
Feed the LM regulator via 1 ohm. Feed emitter of 2N2955 (PNP!) also. Take PNP Base to other side of the 1E resistor (regulator input) and PNP Emitter to regulator output. Now, as load increases the reg. develops voltage across the 1E resistor, and at around 0.6V (0.6A through the regulator), PNP turns on. By the time the regulator is taking 0.7A it is developing 0.7V across the 1E resistor (which is dissipating I^2R = 0.49W), and PNP is turned fully on and well and truly taking the rest of the load! 2 components: 2N2955 (and heatsink of course - water-cooled, anyone?) and 1E 1W resistor. Drop-out voltage = that of the regulator + Vbe(PNP). The 2N2955 is rated to 10A, and you can add many of them by adding a (1A rated) diode in series with the regulator and 1E0 (compensates for the Vbe of the 2955/s), and 0E1 resistors in the emitters. The 2955s are then sharing the load to 10 * Ireg each, well within rating, and all protected by the regulator. Boost the Vout? add 1k regulator out to 'ground' (lifted) and resistors / pot to suit then to ground. This works for *any* LM regulator, just adjust the 'grounding' resistance. From the datasheet, LM317 is 1.2V out so, given 1k across that, the grounding resistor will be about (desired Vout - 1.2) / (1.2 / 1k). So, e.g., given regulator LM7812 and 1k across its output, wanting 13.8V out, grounding resistance will be about (13.8-12) / (12 / 1k) = 150E. Have fun, folks! 73 de Dex ZL2DEX |
Ancel
Allard PE1NWL
Craig Thibodeaux
