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Messages - Monophonia

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1
The RF Workbench / Re: NCP driver sucks
« on: October 15, 2019, 1354 UTC »
I have used the NCP up to 7.290 in the past. Inverting and non-inverting. What keeps them from frying is a few ohms between the driver and the SiC gate. 

2
Shortwave Pirate / Re: XFM 6275 AM 0115 UTC 22 Sep 2019
« on: September 22, 2019, 0348 UTC »
There's a bitter irony to the propagation making the good signals ignore my quiet farm property. :(

3
You described your solution, reading strings as they come over the serial bus.

A few years ago I made a bit of arduino code that read a character from the serial line and did a simple action (relay open, relay close, relay position, etc) I can probably dig up the code from that given time.

In my DDSVFO implementation, I use SI5351a boards since they make a nice strong square wave. They talk to the arduino using I2C. I also use an I2C/HD44780 adapter to drive the display to save I/O on the arduino. The display and Si5351a sit on the same bus, then the rest of the arduino pins are free for buttons, relays, and A/D inputs. My "brain board" uses a single arduino and has enough I/O to drive T/R and sequencing relays, 4 ADCs to sample current, voltage, power, etc. My low level PWM modulator sits on the same board as well.

You have my number, send me an email and I'll share more details.

4
General Radio Discussion / Re: X-FM Halloween 2018 Gear
« on: August 15, 2019, 1340 UTC »
Something tells me you do this professionally  ;)

Then again.... so do I.  ;D

-M

5
The RF Workbench / Re: Beginner class D design
« on: April 20, 2019, 1521 UTC »
Be careful when relying on the gate driver to act as the inverter! If your clock source gets loaded down or slightly shifts duty cycle then your amplifier will be imbalanced.

I ran into this issue at 7Mhz whereupon the gates were being driven 35/65 instead of 50/50.

That breaks things after a while.

My advice, use an external inverter or better yet, a flip-flop driven at 2x frequency, those are good at maintaining an even split. For added protection in case your clock stops, make diode level shifters with decay resistors that prevent the drive signal from remaining high.


See last two posts.

I realized after my design that it looks like the NCP drivers have an inverter built-in. The truth table in the datasheet makes it look like it won't work for this purpose though, but I don't know why else they would have such a feature. Is this to use in a push-pull amplifier with one square wave input? If so, then I don't even need the inverter :P

6
While repairing one of the kiwiSDR's I admin I found that the admin can now enable a mode that allows for more reciever bandwidth at the expense of one channel. It looks like this update went live within the last month.

Now one can have up to 20kHZ audio bandwidth up from 12kHz. This does decrease the available receivers down to three.

I have set up websdr.wc8voa.org:8073 to this mode for a while to play around in. I may change it back soon but if I catch wind of an XFM show I will flip it to wide so we can all take in the high-fidelity.

Try it out, take turns!

7
The RF Workbench / Re: Simple SiC TX
« on: January 09, 2019, 1808 UTC »
Being able to order those oscillators from Digikey on frequency is a plus, If I ever make something that is truly fixed frequency I may explore those.

8
Shortwave Pirate / Re: X-FM 4085 AM 0124 UTC 16 Dec 2018
« on: December 16, 2018, 0232 UTC »
Hear you on the Cincinnati, Ohio Kiwi! S9 +5

9
For Sale / Wanted / Re: 40W GaN Portable Tx
« on: December 02, 2018, 0407 UTC »
Email sent!
You make good stuff.

10
Wrxi, still working on those liners.
Send logs to Wrxiam@gmail.com

11
Shortwave Pirate / Re: UNID 6930.2 AM 2250 UTC 23 Nov 2018
« on: November 24, 2018, 0056 UTC »
That was mine, just toying with the Lulu since it looks like the 500W flamethrower project is moving too slow to make the christmas season.

Thanks for tuning in.

12
For Sale / Wanted / Re: 400W RF GENERATOR
« on: October 29, 2018, 1617 UTC »
Interested to see pictures. I may be inclined to get lazy,

13

The good news is that while TDOA CAN arrive at very good positional fixes, it can also plot positions way far from reality that look great.  And the user, especially the average, uninformed user, may never know the difference.


Yep, Like the first time I attempted a DF test right when the feature launched. It "found" WRMI very firmly in North Carolina.

14
Shortwave Pirate / Re: WRXI 6930.15 MCW 1153 UTC 21 Jul 2018
« on: July 22, 2018, 0134 UTC »
Ah! Somebody heard my 10W pea-whistle into a multi turn mag-loop.

WRXI @ 6931.5!

WRXIAM@gmail.com

15
S9 with noise at websdr.wc8voa.org:8073 VOA museum RX on a cushcraft R7.

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