Well, that's what I was afraid of. It is like trying to make milk from chalk and water, you're going to need a lot more than what you got. In other words, it's impractical.?

I would need proper instructions with a picture and a schematic to pull it off.

So would a digital mode signal be any easier? Something connected to the mic input lines for rtty or psk31 perhaps.

And as for a test tone for tuning an antenna tuner, could a simple sine wave generator circuit inject a signal into the mic input? Does anyone know what kind of power ratings there are for the mic circuit? Some CPO circuits can be loud until you put a resistor on the speaker line.

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Whoops, had a copy-and-paste error. ?That first line should be: ? ?pinMode(4, OUTPUT);

Also, while that first line is typically in the ?setup() ?routine, the other three lines could be most anywhere, and need not be together.

Allison's comments are probably worth chasing a little further. ?Here's a summary of her points, and my comments:

1) ?Diode ring injection level should be higher for the 1n4148's

Likely true. ?An easy fix is to move from 1n4148's to a couple BAT54S's in that DBM. ?Perhaps even try a commercial DBM here if you really know what you want. ?And/or adjust the injection level. ?All easily done.

2) ?DBM wants ports at 50 ohms for better overload and IMD performance

Probably true. ?But 200 ohms works well for feeding the crystal filter, and does reduce power consumed. ?Somebody with the W7ZOI 50 ohm amps might patch them in and feed the filter appropriately, see if the improvement is worthwhile. ?Could be that much of this preference for 50 ohms is because it's a nice standard impedance to look at and test with, and not so much driven by performance. ?

3) ?Recommends diplexer between DBM and crystal filter

One of those things that adds parts and complexity, may well reduce spurious received signals. ?But we seem to have identified all the images and birdies thus far, perhaps this doesn't add much to performance. ?Would be worth trying, do an A/B comparison.

4) ?Too much RF gain

Don Cantrell has a nice hack for this, just shut down power to Q1. ?Though some gain at Q1 might prove useful in some cases. ?Alternately, put a pot on the rx signal between the relays. ? ?If we reduce RF gain we need to increase AF gain, and that will result in greater sensitivity to power supply noise. ?

5) ?Move VFO to high side of IF to reduce images.

Yup. ? My Si5351 VFO will be up around 19mhz, just a matter of Raduino code and moving the BFO a couple khz.

A few other things I'm keeping in mind:

6) ?Q13 can blow, either from a nearby transmitter or from too much power dissipation for a Sot23. ?Use a TO92 there? ?Add Raj's back-to-back diodes?

7) ?Q14 emitter resistor can burn out, find a bigger part?

8) ?Might want Raj's fractional ohm source resistor to protect the IRF510. ?My guess is it's not often seen in an RF power amp because on standard RF transistors the source is attached to the tab which gets grounded to the heat sink. ?Not true with the IRF510. ?Maybe a PolySwitch to limit current.

9) ?Add minor hardware bits needed to support CW, maybe standalone PSK31

10) ?Add features for easy testing.

Jerry, KE7ER

John Smith,

Regarding noTone()

Pin 6 is used in the Raduino sketch for "CW_TONE", Ashhar has it set up to send out a sidetone. ?Probably best to let pin 6 be, pin 4 is free though, it gets defined as "TX_LPF_SEL" but that define is never used. ?I tried my code snippet, the compile complained until noTone() was given a pin number to shut down, even though the library can only generate one tone at a time. ?So working code could be had by adding this anywhere inside the setup() routine in the Raduino sketch, including right at the top as shown here

########################

void setup()

{

? ? inMode(4, OUTPUT);

? ? tone(4, 1000);

? ? delay(5000);

? ? noTone(4);

########################

Note that "4" is labeled as "D4" in the Raduino schematics, and is more a name than a number. ?It is actually pin 22 of the Nano. ? The Nano has pin names 0 through 12, though 8,9,10,11,12 are used by the LiquidCrystal library for the 2x16 LCD. ? These are all strictly digital pins, can be input or output, but have states of only high or low. ?The Nano also has pin names A0 through A7, though A4,A5 are used inside the Si5351 library. ?These can be analog inputs to the ADC (such as for reading the the voltage of that tuning pot), or can be used as digital pins.?

If you plan to mess around with Arduino programming, probably a good idea to get another Nano or two. ?They are quite cheap, and it is possible to program them in such a way that they will no longer talk to you. ?Probably don't want to brick the Nano that came with the Raduino.

Jerry

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Modulated CW (MCW) originally was a AM tone. So you had carrier plus both side-bands.? Receivable on ordinary am receiver.

A pure sine wave into the mic of an ideal SSB transceiver would transmit a clean AIA CW signal. ?In the real world, that sine wave will be distorted, and the carrier not fully suppressed. ?But it does allow you to transmit real CW on any unmodified SSB transceiver

As anybody who has checked in here in the last few months is likely long tired of hearing, I'd prefer generating CW by unbalancing the modulator as per post 20933. ?The DC into the modulator can be easily shaped to avoid key clicks, and this is not a sensitive point in the rig to be adding an extra bit of stuff to. ?What's more, it could make debug of the transmitter easier than it would be if injecting RF further down. ?On the other hand, you could have more parts fail in the transmitter chain and still transmit on CW if you are injecting 7mhz down by the LPF.

Jerry, KE7ER

http://m.banggood.com/Electronic-Plastic-Shell-Cartridge-Handle-Project-Case-Desk-Instrument-200x175x70mm-p-1035473.html?rmmds=search

I had ordered a couple of the Banggood cases and finally got to mounting my BITX40 in it. I'm not done yet but wanted to share some photos of my work so far too give others an idea of whether or not it would fit their needs. I've found it to be perfect for what I wanted and just $10 with a little patience for the delivery out of China. Receive is working great, still figuring out the mic arrangement. So it's a work in progress!

Aside from attempts to use the BitX for what I would call "true CW," i.e., "A1A" mode in which the carrier is directly keyed (with or without shaping) and having a "necessary" bandwidth of only a few hundred Hertz, I'm interested in clarifying the use of what is sometimes (erroneously?) called "modulated" CW (MCW): using SSB modulation to simulate the audible CW tone (in true CW produced by tuning away from zero beat) by injecting a fixed tone into the audio input of an SSB exciter. Though the resulting transmission would sound like CW in an SSB receiver, it wouldn't be intelligible in a CW-only receiver, nor would it occupy a narrow bandwidth like true CW. Moreover, since it would be SSB modulated rather than A1A CW, its use would not be permissible in the CW-only portions of the amateur bands. Those portions are reserved only for the narrow bandwidth of true CW, and an SSB-generated CW-like signal would take up as much bandwidth as several closely-spaced true CW ones.

Have I understood this correctly?

73,

Todd K7TFC

That's shipped out of California.

If you have more weeks than you do dollars, there's cheaper.

noTone(); is a line of C code that you add to the sketch.

For example, if you hack the Raduino sketch to add these four lines inside the setup() routine:

  pinMode(6, OUTPUT);
  tone(6, 1000);
  delay(5000);
  noTone();

Sounds good. ? My head is usually down in the bare metal somewhere, and my coding style will reflect that.

For a good taste, take a look at the KE7ER/pskuc.c down in the files section, search for the "README" to get an overview. ? I was rather proud of that one. ? Though now in 2017 we'd probably be better off spending an extra dollar for an Arm Cortex M3 Arduino compatible: ?? No longer much point in shoehorning standalone PSK31 into a machine with 2kbytes of flash.

Jerry, KE7ER