Work in progress, for now setting up the structure and adding content.
To:
From: "Tony Parks"
Subject: Re: [softrock40] Re: RXTX Frequency is wrong
Hi Bob,
Is your kit a 40m/30m kit or a 40m/80m kit? If it is a 40m/30m kit (yellow cores for winding the inductors) then the 30m crystal is a 40.5 MHz crystal. If you have a 40m/80m kit (red cores for winding the inductors) then you should have a 28.224 MHz and a 28.06 MHz supplied with the kit.
Thanks and 73,
Tony KB9YIG
To:
From: "Tony Parks"
Subject: Re: [softrock40] SR v6.2 layout
Hi Benny,
The ICs that mount on the bottom of the v6.2 SoftRock Lite board are such that if an IC provided in the kit fits a location then it is the right IC for that location. Look for the small "1" marks in the bottom-side copper. The pin one corner of an SOIC part is the lower left corner when the writting on the IC can be read upright from left to right.
Yes, the nine 1206 capacitor locations are for the 0.1uF SMT capacitors provided in the kit.
73,
Tony KB9YIG
It is with some considerable trepidation that I embark on what promises to be a challenging journey. I have just received my Softrock RXTX V6.2 kit (minus a heat sink that is en route) and am looking forward to its completion. I say that I do this with trepidation since I am very much the klutz when it comes to these tiny kits. My previous experience was over 30 years ago with Heathkits and their check-off-this-step-and-move-on-to-the-next-step approach. Even then, I managed to fail more than my share of smoke tests. More recently, I "completed" the Softrock 40/30 V6 RX kit. It still is not working but I can at least take consolation in the fact that when I reached the end, there were no parts left over! I continue to work with my patient Elmer, Bill, AE5BK, on getting that kit to come to life. My plan in this blog is to work through the kit as methodically as possible, sharing my experiences and lessons learned at each point where I pause to take a breath and evaluate progress to-date. At each such point, I will upload photo(s) of the board and its progress, along with observations on what I did (or failed to do) and/or what I could have done better. Hopefully, this blog will be useful to some and, if not useful, entertaining to others. In the beginning: Upon having received the kit in a compact plain brown wrapper, I immediately sat down to inventory the contents of the 8 bags therein against the bill of materials. I began with the resistor bag. Since I am color blind and have nearly 70 years of wear and tear on eyes that started out weak, I chose to use my DMM to verify all of the resistor values and tape the resistors to a piece of stiff paper in rows corresponding to their sequence in the BOM. Next came the capacitors. The orange-drop ceramic caps were very difficult to read (those darned eyes again). I got my best results using a combination of a 10X microscope (very neat "toy" that hooks into your PC via USB - rationalized its purchase as essential to the ongoing education of the grandkids) and my DMM's limited capacitance measuring capability. I can see already how the microscope will come in handy in looking for bad solder joints/bridges, etc. All the caps were there. For each ceramic capacitor, I ensured it was taped to an appropriately sized piece of cardboard, upon which I annotated the value and the schematic label (e.g., C8). As in my previous kit, the electrolytic caps did not appear to have any markings that one could remotely construe as "+". There was, however, a silkscreened rectangle on each that could be construed as a "-". In this kit, the positive leads can readily be identified because they are the longer leads. The core bags came with the appropriate coils of magnet wire. I learned on my previous kit to have a stock of magnet wire on hand. I had to redo some windings in that one. Looking at the builder's notes, I have no doubt that I will be tapping that stock some more in this kit! I do not look forward to winding those tiny toroids and binocular cores. The rest of the bags inventoried OK. There were some issues with the heat sinks. First, being a newbie to this modern era in homebrewing, I was in a quandary as to how to recognize the TO18 vs. the TO220 heat sink. This was exacerbated by the fact that there appeared to be only one heat sink in the hardware bag. After some research, I identified the heat sink that WAS in the bag as the TO220 heatsink (by comparing its footprint to that of the TO220 Sil-Pad, which was, for some reason, in the Cores bag. The TO18 heatsink was missing. A quick trip to the Softrock group with a question and Tony came back with the response that some of the kits had inadvertently been shipped without the TO18 heatsink and mine would be shipped to me ASAP. Planning the project: From my experiences with the Softrock 40.30 RX kit, I knew that I was likely going to want to view and/or measure points on the underside of the board at various stages of the construction process. With the earlier kit, I made a couple of errors in identifying the correct (unmarked) hole on the underside and I wanted to avoid them with this new, more complex PCB layout. So the first effort – did I mention I am retired and have plenty of time to do this stuff? – was to map the components to the appropriate points on the bottom of the board. I took a digital picture of the bottom and top of the board and then hand-annotated the bottom with essentially the mirror image of the info on the top. The result is in the PDF file named rxtxv6.2_40_30m_BoardBottom_Annotated.pdf. Please note that the annotations may be in multiple colors, but there is absolutely no significance to be given to that fact. That is a result of my color blindness: because the lighting for the photo was bright in some areas and darker in others, I simply chose the “colors” that gave my colorblind view of the board the best contrast. To the color–sighted, the result may be ugly. Tough. Next installment: As one who has learned to look before he leaps, rather than start soldering and snipping right away, I will take Tony’s builder’s notes and expand them into a “Heathkit-like” step-by-step approach. This is not because I find any fault with Tony’s excellent and concise notes. Rather, it is because I work better when I can check off steps. Plus, the effort of “steppizing” the notes forces me to more thoroughly consider and understand the notes and their import. So the next entry in this rambling treatise will be the step-by-step notes. They will be liberally embellished with graphics where that could help (remember Heathkit?) For example, Tony’s instructions on the hole placement for the Transformers will be accompanied by snippets from the board silkscreen. These may result in larger than normal PDFs. Hopefully, this will not deter you from downloading and using/commenting/etc. 73, DE WB5RVZ
From: John
To: softrock40@yahoogroups.com
Sent: Thursday, March 22, 2007 3:24 PM
Subject: [softrock40] 40m/80m RxTx v6.1 no rx
Hi,
I'm building an RxTx 6.1 40/80 meter kit and in initial testing I get
829 Ohms from ground to the IC supply leads. The radio draws approx. 37
milliamps on 12v. And I'm getting 4.9v to all the IC supply leads, but
when I connect it to my Laptop line in running Rocky I do not see any
change in the waterfall or spectrum displays. I tried the radio on 2
desktop PC's at work still nothing.
I tested the cable end to the board with my multimeter and it looks
good from the connector tip to tip, ring to ring and shield to ground.
I connected my old Teck 495 O scope to the output and I don't see any I
or Q signals. Putting the scope on the 4x and 8x jumper pins shows the
crystal oscillating. I've gone over the board with my magnifier and
touched up any questionable solder joints but I still have the same
results.
Any ideas where should I look or try next?
Thanks
John KE7JXM
Hi John,
Your supply current is about right for the 40m kit. Check to make sure pins 1 and 7 of U8 are at about 2.5 volts DC. Also check the signal path from the antenna to the primary of T4 and make sure each inductor lead, (L3, L4, L5 and L6), and the primary of T4 are soldered to their pads properly. Also make sure pins 1 and 15 of U7 are less than 0.5 volts and that the gate of Q6 is at about 12 volts DC.
If the above items are all good then it may be T4 is not wired correctly to its pads which can reduce the sensitivity of the receiver by a factor of 100.
73,
Tony KB9YIIG
From: Ray Benton
To: softrock40@yahoogroups.com
Sent: Thursday, April 05, 2007 8:56 AM
Subject: [softrock40] RXTX with 4mhz crystal Dead Oscillator
Hi All,
I have a RXTX in which the local oscillator works fine until I use
the 16mhz xtal. The signal from the output of Q10 is not as strong as
when I use a 28mhz xtal. Thus Q11 is not turned on. Checking with an
rf probe shows .7v with the 28 mhz xtal and only .2v with the 16mhz
xtal at the base of Q11.
I have tried two 16 mhz xtals .. both with the same result.
What can I do to correct this situation? Thanks to all. Ray W7RJC
Hi Ray,
The capacitors in the oscillator circuit may need to be changed for the lower frequency crystal.
I usually use C48=220pF and C49=100pf for crystals in that frequency range.
73,
Tony KB9YIG
To:
From: "Tony Parks"
Subject: Re: [softrock40] SoftRock40 Lite ... a bit deaf
Hi Tom,
The SoftRock Lite RX should have a sensitivity of about -110 dBm if working properly. If you have a calibrated source this is easy to checked. Listening tests require a 50 ohm antenna connected between the ANT IN-RTN plated through holes at the edge of the board near the crystal. (The antenna return connection is isolated from the circuit ground by the transformer T1.)
Other problems on the circuit board that can result in low sensitivity include bad solder joints at L1 and T1. Also if the secondary windings of T1 are not connected properly there can be a 40 dB sensitivity loss. Please see the builder's note for information on proper connection of T1. Another quick check to to make sure the op-amp U5 is not saturated by checking the voltage on pins 1 and 7 referenced to circuit ground. These two voltages should be about 2.5 VDC.
73,
Tony KB9YIG
To:
From: "Tony Parks"
Subject: Re: [softrock40] Re: Dead clock
Hi Peter,
The oscillator circuit for 30m in the 40m/30m version of the RXTXv6.1 should have C49 omitted. R56 should be 22.1k and the other components as indicated on the schematic. In some cases the activity of the 40.5 MHz crystal has been a bit low and R56 may need to be reduced to 15k to get proper clocking on 30m.
Please post what you find concerning the 30m operation.
Thanks and 73,
Tony KB9YIG
From: paulradge
To: softrock40@yahoogroups.com
Sent: Saturday, April 07, 2007 12:57 AM
Subject: [softrock40] RXTX please check my voltages
Hi all,
i borrowed a cro off a mate and took these measurements running
the m0kgk IQ generator both tones at 1khz with manual 12v on ptt ,,,,
audio input from pc = 0.3Vpp,,,,,,,,(R3/R9=4.9k),,,is this too low should i
increase volume output level on the pc ???
T1 output = 0.4Vpp
T2 output,,,,ie hot side(not the center tap) R26 = 1.2Vpp
R27 =
1.2Vpp
T3 output = 12Vpp
ANT out = 12Vpp
in the shack on my ft817 i'm rx'ving the oscilator and a single tx carrier
so i think my issue with T1 is fixed,,,i'm measuring gain through Q2 & Q3/Q4
so i think all is well there
i still can't measure any output on 3 different power meters but in
theory the cro is saying 12Vpp on the ant output so can i use P=Vsquared on
R ???
12 X 0.707 = 8.4 rms
8.4 x 8.4 = 70.56 / 50 ohms = 1.4watts or have i got something wrong?????
and any comments on the 0.3Vpp off the soundcard please ,,,?
almost there,
Paul
Hi Paul,
Your RF output calculation should be the (Vp-p / 2 )*0.707 to give RMS RF volts output.
Then square the RMS volts and divide by 50 to get the power output which in your case will be 0.36 watts.
The 0.36 watts output is about right for your soundcard line-out voltage to the board.
73,
Tony KB9YIG
From: lbeugnet
To: softrock40@yahoogroups.com
Sent: Friday, May 25, 2007 9:33 AM
Subject: [softrock40] rf power level
Hi Tony & all
My SRv6.1 80/40 is finally working...
One specific question regarding the output level:
- my sound card (sb live 16) delivers 2.6 v PP on each channel at most,
- the rf level mesured on a 50 ohms dummy load is 14.4 v pp ( = about
0.4 Watt)
Is this output level value correct with such an input level, or is there
an issue in the amplifier chain ?
If not, I guess I have to change the amplifier gain of U1 & U2, by
modifying the feedback resistors R4 & R10 ? Do you agree ? Or any other
idea ?
Thanks for your advise!
73 Laurent F6GOX Paris
Hi Laurent,
Extra 4.99k resistors were provided in the RXTXv6.1 kit to increase the TX audio gain. Resistors R3 and R9 may be reduced to 4.99k to increase the gain.
73,
Tony KB9YIG
To:
From: "Tony Parks"
Subject: Re: [softrock40] Re: rf power level
Hi Mike,
With the Delta 44 soundcard you can go to its M Audio Delta Control Panel and increase the Outputs range to +4 dBu. This will give you more output to drive the RXTXv6.1 board. Also make sure you have added the 0.1 uF capacitor from the gate of Q6 to ground. Without this capacitor the RF output will be low.
73,
Tony KB9YIG
Although the following email is about a SoftRock V5, compare the schematic to your version as it addresses things in common to all receivers.
To:
From: "Tony Parks"
Subject: Re: [softrock40] Re: SRv5 - 1/2 actual soundcard bandwidth - confusion ?!?
Any place in the SoftRock circuit or connection to the soundcard that
seriously affects one of the audio channels will result in little or no
image rejection. This can include items on the OSC/BPF board, the QSD board
or even the soundcard input. Some things to check wold include the
following:
1. R25 and C25 values on each of the OSC/BPF boards.
In a number of cases the OSC/BPF kits were shipped with a 100k resistor for
R25 rather than the correct value of 1k. Measure the resistance between
pins 5 and 6 on the 15-pin header to make sure R25 is 1k. Read the value
code on C25 to be 151 (150pF) for 40m and 470 (47pF) for 20m.
2. Wiring on secondary of T21.
The resistance between pin 9 and 10 on the 15-pin header should read about
zero. Also the resistance between pins 9 and 11 should read about zero.
Along with the correct resistance readings the wires connected to via 6 and
via 3 on the T21 mounting position should come out of opposite side of the
T21 core, one out of the top and one out of the bottom.
3. If you have a scope then view the waveforms on pins 5 and 8 of the
15-pin header. Both should be fairly symmetic square waves with the
waveform on pin 8 lagging 90 degrees compared to the waveform on pin 5.
(Circuit ground is at pin 12 of the header.)
4. The DC voltage at pin 9 of the 15-pin header should be close to 2.5 VDC.
5. The DC voltage at the + wire on C13 and C14 should both be close to 2.5
VDC.
6. Make sure you really are plugged into the line-in on your soundcard and
the soundcard is selected by the SDR program in use.
Hope the above make sense and will help a bit.
73,
Tony KB9YIG
To: softrock40@yahoogroups.com
From: "kb9yig"
Subject: [softrock40] 40m/30m RXTXv6.1 operation
Good Evening All,
This afternoon I finished the build of a 40m/30m RXTXv6.1 that I
started yesterday. Total build time was about seven hours.
The 40m RX function was working properly on first application of
power with a center frequency of 7.055 MHz. However, the 30m RX
function was not working properly which was traced to low amplitude
40.5 MHz clock output from Q11, the oscillator buffer stage. Output
from Q11 became solid for clocking the FFs after the value of R56 was
lowered from 22.1k to 15k.
I have seen this problem before with 30m SoftRock receivers where a
combination of 40.5 MHz crystal activity and transistor gain result
in a too low amplitude clock signal to the FFs. This will be
something to watch for in the 30m/40m kit.
After getting the 30m RX function working properly a test was made of
TX output to a 50 ohm load by using a quadrature audio line-out
signal to the board. On both 30m and 40m about 1.2V p-p quadrature
audio input produced one watt output where R3=R9=4.99k on the circuit
board. Max power output was greater than 1.3 watts on both bands when
the audio input was increased to around 2V p-p. The output sine wave
looked clean with the carrier suppression greater than 50 dB on both
bands. Others who have a spectrum analyzer will need to confirm that
spurious emissions are below the -43 dB FCC requirement.
Quite a few of the 40m/30m kits have been shipped in recent weeks and
I wonder if other examples of this kit have been built and tested.
Please post your experience with RXTXv6.1 30m operation or problems.
Thanks and 73,
Tony KB9YIG
Under construction, content coming soon.
Under Construction, content coming soon.