Thursday, June 9, 2016

Another New Transceiver from N6QW

Time for Another Transceiver!


The 60M Arduino Sketch  code is now posted on Noteworthy is that the code includes the ability to auto switch the band pass and low pass filters depending on which button is depressed


6/12/2016 ~ More Refinements

I will soon post the code in .txt format on my website I am happy to report that I now have the capability that as you change  from the 60M channels to the 40M channels that signal outputs are available to change the Band Pass and Low Pass Filters. So there is automatic band switching which makes essentially the full operation follow what ever is punched in on the keypad. USB and LSB  switching is retained.

Have received some inputs about eliminating the display entirely and by using 4 LED's the channel readout would be in binary format. Another suggestion was to eliminate the keypad and use the encoder to either act as a normal VFO or that it could have a mode to simply spin through the channels in the channel mode. I was provided seed code to start that process --so that may be the next task.

I managed to find two fifteen minute time slots so was able to build the audio amp stage a NE5534 driving an LM-380. About 6 months ago I cut the audio amp board on the CNC and thought it might come in handy --it did. You can see the audio amp board next to the main board.

Having standard designs plus having the computer programs for the CNC makes cutting boards pretty easy. Most likely the next 15 minute project will be the microphone amp. A thought-- because the board is so small is to make it a vertical board that will be soldered to the bottom of the audio amp board.

Pete N6QW

6/10/2016 ~ The Arduino Code is in initial testing!

Late Breaking News now on a 8X2 Display!!!!

Again I am following the path of using what I have and spending my time wisely as I have so little available. Since 60M is channelized with 5 channels there is not much need for an encoder and all that is needed is to select the proper channel. I made an attempt to use a couple of toggle switches and decode the position of the switches to select the channels --that did not end up too well.
Next I thought about using a keypad like in the conversion of the Ten Tec Model 150A and that led to success! I first stripped down that code so all of the "tuning" crap was removed and then set up the code so when you press Key # 1 you are on Channel #1. Having a  12 position keypad that left 7 open "channels". So then I thought about 9A2ZX's post that 60M was evidently not very exciting and so my horizons were expanded to think beyond 60M. I am happy to report we now have a 60/40M transceiver. Here is the channel line up.
Channel #1 ~ 5330.5 KHz
Channel #2 ~ 5346.5 KHz
Channel #3 ~ 5357.0 KHz
Channel #4 ~ 5371.5 KHz
Channel #5 ~ 5403.5 KHZ
Channel #6 ~ 5.0000 MHz (Check for time and propagation)
Channel #7 ~ 7.2000 MHz
Channel #8 ~ 7.2130 MHz
Channel #9 ~ 7.1850 MHz
Channel #10 ~ 7.2350 MHz (* Key)
Channel #11 ~ 7.0386 MHz (0 Key)
Channel #12 ~ 7.0300 MHz (# Key) [Or 7.078 MHz]
In examining my 40M operating habits, I find there are a couple of frequencies where I do most of my "yaking" and thus that directed my choice. Now if one desires so, it is not difficult to add back in the encoder. I did retain the LSB/USB switching capability as USB is typically used for WSPR or Digital Modes; but on 40 Meters typically it is LSB.
The coding effort was largely driven by lack of time --so working in 15 minute blocks you get what I got. I will do a bit more testing on the code and then make it available. AS of right now I am using a 16X2 display. Given the channel type operation the plan is to migrate this to a 8X2. Stay tuned --more fun to come.
Pete N6QW
We are on a roll here not so much for starting all the way from scratch as it is to take what is in the bins and making it into something new. When I made the conscious decision to cannibalize the original Let's Build Something prototype, the flood gates were opened and I found by combining other pieces I had in the junk box this provided the seed not for just one new transceiver but several transceivers. So check your junk box and see what is available.
Staring me right in the eye was the mainboard which had discrete components Plessey bilateral amplifiers and a 4.9152 MHz filter, which looked like this.
The first thought was how to use this in a somewhat different form. Since I had now freed up a 3.180 MHz crystal filter (Model XF-30A from an early Yaesu FT- 101) this would be a good fit for this board. I also convinced myself to quit using homebrew DBM's and move to the SBL-1. So now the board looks like this and in a minute you'll see the why of these changes. I used a small vertical board to mount the SBL-1 and you can see that along the right hand edge.

A Radical Departure & Proposal ...

So ok let's talk a minute about 60 Meters. The 60M band here in the US has been in existence for some time; but has some significant limitations including 5 specific frequencies (or channels) and a rather low power limitation --no kilowatt stations here. But given its position between the 75/80 Meter band and the 40 Meter band, 60 Meters  has some interesting propagation attributes. Did I mention not many problems with QRM. Also most operations are USB (or CW).
The FCC is kind of picky about using the specific channel frequencies and this is where the Si5351 can really shine. In fact the Si5351 was intended to generate specific clock frequencies but the ham community figured out how to turn the PLL into a VFO.  So why not use three of the Arduino Pins to program the 5 channels. Two of the switches would give 4 channels and the 3rd switch would give the 5th channel. For VFO operation three Arduino pins are used so there is no loss of pins.
By using five specific channels there would be no need for an encoder although one could be included to provide a "clarifier" function on receive only. The transmit side would be locked to the 5 channels. Notionally it appears that the Arduino programming would be greatly simplified if only 5 channels were required. NOTE: At this point I have not even done one line of code so don't ask for the sketch.
The simple 16X2 LCD  (or maybe even a 8x2) display shown in an earlier blog entry could provide a display for the channel and mode information. I would use my proven modules for the other blocks. A single 2N3904 Microphone amplifier coupled with a NE5534 and LM380 would be for the Audio output. The 2N3904's in the bidirectional amp stage would handle receive RF amplification and the transmit pre-driver. The standard 2N3904 and 2N3866 would once again be used for the transmit driver and the IRF510 for the final stage. I figure 10 watts would be a good starter for this band.
Right now this is all at the noodling stage but it does look feasible. I am unaware of many homebrew 60M transceivers but given that almost the exact same circuitry has been used successfully on 80/40/20 Meters it is reasonable to assume it would work. But we may be plowing some new ground here.

Frequency Noodling: Since I will be placing the LO above the incoming frequency there will be a sideband inversion and thus the normal LSB BFO frequency will be used for USB. Thus with a 3.180 MHz filter the 3.181500 BFO frequency would be used for USB reception and transmission. In calculating the channel LO frequencies we must add the 3.1815 MHz to the 5 specific channel frequencies and that is how the Arduino/Si5351 would be programmed

Channel #1    5.3305 MHz  LO set to 8.512 MHz
Channel #2    5.3465 MHz  LO set to 8.528 MHz
Channel #3    5.3570 MHz  LO set to 8.538.5 MHz
Channel #4    5.3715 MHz  LO set to 8.553 MHz
Channel #5    5.4035 MHz  LO set to 8.585 MHz

From my initial look see the 3.180 MHz  harmonics don't fall within the Band Pass Filter range and the Low Pass Filter cutoff could be set at 5.8 MHz, which should make everyone happy.
Share your thoughts on this project and email me at
Pete N6QW