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12 bucks and a handful of parts or Building and using the Soft Rock lite




 
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Author Topic: 12 bucks and a handful of parts or Building and using the Soft Rock lite  (Read 66920 times)
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WA1GFZ
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« Reply #75 on: February 18, 2008, 09:40:45 PM »

That is a great article Jack. My home brew QSD will do 25 volts output with 2.5 volts going in but no sound card including HPSDR can handle that kind of dynamic range. Even the SR6 pushes the limit of a sound card signal handling. The 5 volt supply on the op amps is more than enough to make the sound card the limit of performance. 600 ohm isolation transformers is a great idea I have not tried yet. I can't open up the HPSDR because of hum. The best 600 ohm transformer I have ever seen is a MIL-T-27 made by Pico rated for 5 watts. I used one in a design once at 1 volt and the frequency response was impressive.
Bear you only need one SR6 to do both functions unless you want one broadband input and the other tight. You could just switch the input.

It is interesting to listen to normal RX audio compared to sound card output. It takes a while to get used to the processing delay. I have not seen a case when Flex software outperformed the RA6830 under poor conditions BUT I have seen Alberto's software outperform the Racal under high noise conditions.
The HPSDR guys are talking about PDM and EER SSB with the new module coming in May. This is to drive a class e final.
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« Reply #76 on: February 19, 2008, 09:44:04 PM »

OK Frank

Here's the latest.

I installed a pad on the IF input. I am using a 1k pot across the IF feed and the wiper feeds the SR input. This allows me about a 50db adjustment to dial in the input voltage.

I set the noise floor by unhooking the ant and setting the noise floor at -140dbm. Then I hooked up the ant. You are looking at the crystal calibrator in the R390a.

This could be a great tool for anyone using an BA to use the SR to set the level going into the SR since all radios will have different IF levels. Thanks to Bill KA8WTK and Buddly WD8BIL for their help with this.

Thoughts?



* withpadsr.JPG (167.38 KB, 1027x773 - viewed 1096 times.)
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WA1GFZ
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« Reply #77 on: February 19, 2008, 10:07:48 PM »

Looks good Gary. I think you can raise the RF input a bit. Now it would be cool if you could look at a crystal oscillator about 20 to 30 dB stronger so I could see the
oscillator sidebands. Looks like it is about 400 hz wide at 70 dB down. I would like to see the width at 100 dB down so it will take a stronger signal. It needs to be a crystal oscillator that is clean like a reference out of a radio of piece of test equipment. I would like to bounce it off the data I collected on my set up. I'll be glad to compare data but the 390 should be cleaner. I would put the variable resistor in series with a 47 or 51 ohm resistor to ground and feed the SR across the 50 ohms. The SR needs to see a good input Z for best performance.. 
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W1VD
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« Reply #78 on: March 03, 2008, 08:54:01 AM »

Frank GFZ

Think this might be the pix you were looking for...


The above was taken using one of my receiver crystal test oscillators into the R390A. Receiver was operated in MGC mode, i-f output through a step attenuator to the SoftRock and into an M Delta 44 sound card. 

In going through my receiver data apparently I've never measured R-390A phase noise (hard to believe!) so decided to do so while it was set up. The following was measured using crystal oscillators, a pair of HP8640Bs, step attenuators and true RMS voltmeter in standard receiver testing fashion.   

MDS (.1 kHz BW): -141 dBm

Blocking dynamic range (20 kHz): 115 dB

IMD dynamic range (20 kHz): 82 dB

Phase noise - receiver bandwidth 1 kHz

Freq.     dbc/Hz
1 kHz     -100*
2 kHz     -115*
5 kHz     -134
10 kHz     -138
20 kHz     -146
30 kHz     -152
50 kHz     -152
100 kHz     -152

* phase noise measurement compromised due to beat note - poor opposite sideband rejection with 1 kHz filter - performance would be much better than shown if not for the beat note. Makes me want to try a good 500 Hz wide mechanical filter in place of the relatively useless 2 kHz.

Also made interesting measurements of R-390A i-f output linearity for various MGC settings as well as SoftRock and Delta 44 overload levels in order to optimize the R390A / SoftRock setup. Will see if I can get it together in a usable form and post here or in a new thread...if there's any interest...

Jay

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WA1GFZ
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« Reply #79 on: March 03, 2008, 09:15:57 AM »

TNX Jay I'll study this, but man that 390 is clean. I'll add it to my EXCEL record of RX phase noise. Jay can you give me 200 Hz and 500 Hz.
Did you do 20 dB correction for 100 Hz. BW?

Jay, How about doing your RF 590 while you are at it. I looked at my EXCEL and the 390 blows away the best synthesizer. Maybe I should have kept my 390 and done a hot rod job on the dynamic range and add 20 more dB.

we can now compare this the HPSDR and QSR1
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W1VD
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« Reply #80 on: March 03, 2008, 10:48:10 AM »

The phase noise measurements were made in the 1 kHz BW position - therefore a 30 dB correction was used.

No point in trying to measure the phase noise at 200 and 500 Hz offset because of the large opposite sideband tone leaking through the 0.1 and 1 kHz filters. The measurements at 1 and 2 kHz were also compromised as noted. Without a better i-f filter the measurement isn't possible... unless one were to notch the tone.

Sent measurements on the RF-590 about 6 months ago  - here they are in case they've been misplaced. 

MDS (.3 kHz BW): -130 dBm

Blocking dynamic range (20 kHz): 104 dB

IMD dynamic range (20 kHz): 82 dB

Phase noise - receiver bandwidth .3 kHz

Freq.     dbc/Hz
0.5 kHz     -69*
1 kHz     -94
2 kHz     -93
3 kHz     -93
5 kHz     -93
10 kHz     -98
20 kHz     -108
30 kHz     -130
50 kHz     -137
100 kHz     -150

* phase noise measurement compromised due to coherent tone from synthesizer

Please send a copy of your phase noise spreadsheet - had one but can't find it. The clean display you see for the R-390A is after a some attention to reducing ground loops, hum and other sources of noise in the SoftRock setup. Agree the R-390A would be the hot ticket with another 20 dB IMD dynamic range. Data on the i-f linearity to follow...
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WA1GFZ
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« Reply #81 on: March 03, 2008, 11:53:10 AM »

Jay,
I'll add both and send it again.
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WA1GFZ
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« Reply #82 on: March 03, 2008, 08:19:08 PM »

Well hands down the R390A wins cleanest LO but suffers in the dynamic range dept. It will be interesting to see how the latest SDR configurations compare.
That is the real reason I wanted to see the R390A phase noise. Even looking at Jays spectrum display you don't see the blob of phase noise between 1 and 10 KHz dBC.
now Jay hang your soft rock off the 590 and you will see the difference. As you see from my EXCEL the 590 is one of the cleaner sources. I bet your R599 is also pretty clean.   
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Steve - WB3HUZ
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« Reply #83 on: March 03, 2008, 08:20:33 PM »

Makes you wonder what a 390 with a 7360 front end would do?
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WA1GFZ
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« Reply #84 on: March 03, 2008, 08:28:55 PM »

I think the 7360 in place of the 6C4 mixers would be quite the RX.
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W1VD
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« Reply #85 on: March 04, 2008, 08:19:18 AM »

First a typo correction...the IMD dynamic range on the RF-590 is 88 dB not 82 dB.

Here's a shot of the RF-590 into the SoftRock. The elevated 'noise floor' is the phase noise. With step attenuators between the crystal oscillator and receiver and between the RF 590 and SoftRock it's easy to verify that everything is operating linearly. With an input signal above about -40 dBm (S9+33) the phase noise rises out of the receiver noise floor...   


Roger the 7360s! Recall the article by W2QWS? ... he used 7360s in the 75A4 1st and 2nd mixers. Don't think there were any hard numbers on improvement though. Guess it's time to pick up a spare 390A rf deck and have at it.

Got the latest QEX yesterday. Step aside Clapton ... 'Drentea is God'... Wink

   
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WA1GFZ
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« Reply #86 on: March 04, 2008, 09:04:51 AM »

thanks Jay,
I need to study this some more. I still think your dynamic range should be higher at 20 KHz unless the roofing filters are very wide.
I would think it should be well into the 90s. my hotrod Racal is around 100 dB and a stock one is around 95 dB. I like the 590 first IF better than the stock 6830.
Yes, Drentea's radio is something else. The only thing that caught my eye was the attenuator ahead of the LO input to the SD5000.
Maybe it is an error but why a 15 dB pad??? I have a jar of these amps ant considered using them at one point but stuck with MMICs and 2n5109s. That FET Norton amp is very cool. I have a copy of his book around the house somewhere. Notice his references to Hendrix
(Rohde) Imagine the man hours he put into that work of art?
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WA1GFZ
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« Reply #87 on: March 04, 2008, 11:21:24 AM »

Now here is a question. Notice the measured numbers match the display for the R390 but they do not match the numbers for the 590.
I don't know why but I think it has something to do with the BW correction and the way the FFT works. some smart guy wanna set me straight here.
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W1VD
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« Reply #88 on: March 04, 2008, 02:44:30 PM »

Here's some info on R-390A i-f linearity and PowerSDR S meter/display calibration using manual gain control MGC mode.

The SoftRock will output 4 volts p-p before the onset of clipping...so make sure the Softrock's output will not overpower your sound card. I'm using a Delta 44 card and it will accept up to 10 volts p-p before bad things happen - other sound cards are likely different. The 455 kHz level into a stock Softrock (1000 ohm op amp feedback resistors) that's just shy of pushing the output into clipping is -6 dBm. Under all circumstances one will want to keep the level into the SoftRock below this level.

With that in mind here is what the i-f output of my R-390A looks like with different signal generator levels. Other receivers will likely be somewhat different. S meter readings are shown just to give some meaning to the -dBm numbers. The i-f output levels are shown for the receiver in AGC mode with the rf gain control at the full up 10 position. Also shown are the i-f output levels in manual gain control MGC at several different setting of the rf gain control 7, 8 , 8-1/2, 9 and 10.

            Generator      AGC 10     MGC 7      MGC 8       MGC 8-1/2       MGC 9       MGC 10
           -113 dBm      -43 dBm                   -85 dBm      -71 dBm      -62 dBm      -37 dBm
           -103 dBm      -38 dBm                   -75 dBm      -61 dBm      -52 dBm      -27 dBm
           -93 dBm      -35 dBm                   -65 dBm      -51 dBm      -42 dBm      -18 dBm
           -83 dBm      -31 dBm                   -56 dBm      -41 dBm      -32 dBm      -8 dBm
S9         -73 dBm      -29 dBm                   -45 dBm      -31 dBm      -22 dBm      +3 dBm
S9 +10     -63 dBm      -27 dBm                   -34 dBm      -21 dBm      -11 dBm      +10 dBm*
S9 +20     -53 dBm      -26 dBm      -78 dBm      -24 dBm      -11 dBm      -1 dBm      +15 dBm*
S9 +30     -43 dBm      -26 dBm      -68 dBm      -14 dBm      -1 dBm      +8 dBm
S9 +40     -33 dBm      -25 dBm      -58 dBm      -4 dBm      +9 dBm      +12 dBm*
S9 +50     -23 dBm      -24 dBm      -48 dBm      +7 dBm      +12 dBm*      +16 dBm*
S9 +60     -13 dBm      -22 dBm      -32 dBm      +12 dBm*      +16 dBm*
S9 +70     -3 dBm      -22 dBm      -2 dBm      +16 dBm*

* = gain compression

In case the chart above isn't readable http://www.w1vd.com/R-390A IF output.PDF
   
In terms of dynamic range the MGC 10 setting is not a good choice because gain compression starts at only S9+10 dB. Similarly the MGC 7 is a poor setting due to the wild nonlinearity. I've been using MGC 8-1/2. Since the receiver will go into gain compression just north of +9 dBm i-f output, I use 15 dB of attenuation between the  R-390A and the Softrock. This reduces the i-f output level to -6 dBm... the maximum SoftRock input. The sound card input level and/or PowerSDR 'preamplifier' low, med or high position can be used to accurately calibrate the s meter and display.

What does one do with signals bigger than S9+40? This is a good application for a step attenuator ahead of the receiver...or one can go 'uncal' and reduce the MGC setting.  One note: MGC settings below 9 negatively impact the minimum discernible signal at around -130 dBm at the far other extreme.   
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« Reply #89 on: March 04, 2008, 06:37:52 PM »

I guess I can afford $12 bucks. It would be something to check out. I'll print these many pages coz some replies refer to I.F. levels and audio levels for clean response and calibration of the card/software.
The synch detector is of interest to me for listening to music on Short Wave. I'm getting tired of switching between a vertical, a 600 foot long wire, and dipole to find the least distorted signal.
It's time to play a little.
Fred
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« Reply #90 on: March 05, 2008, 10:33:22 AM »

I assembled an 8.83 IF kit for Ralph, W3GL.  This was my first attempt with SMT's, and small components.  It went together quite easily.  For those timid of surface mount technology, don't fret.  You need a good grounded soldering station, thin solder, a magnifying lamp, and a means of holding the 1 inch square board in place.  I used a toothpick to maneuver the parts in place after dropping a dab of solder on a pad.  The biggest hassle was winding the toroids.  It was a fun little project.  If I can do it, almost anyone can.
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WA1GFZ
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« Reply #91 on: March 05, 2008, 10:41:29 AM »

At the least $12 buys you one nice spectrum display.
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Are FETs supposed to glow like that?


« Reply #92 on: March 05, 2008, 11:20:31 AM »

I would suggest getting ahold of a small syringe of paste solder...

If you have more than one smt project in mind....

The stuff works like magic!

It is sticky enough to hold the part in place, and solders in a heart-beat with a 10-15 watt iron....


I soldered a 48 pin TQFP Ic last night... (<3/8" square)... and wow.. it was indeed painless!

Along with dozens of 0805 size caps/resistors.

A little dab of solder paste....drop the part on with tweezers... hold the top of the part with the tweezers.....touch the pad with the iron, for about 1 second...

Getting a little more practice with the SMDs ... it's becoming fun!


I have some very small wire solder (0.012")  if anyone needs enough for a kit, I'd be happy to send you a chunk....

I could offer some paste solder as well... because it is expensive, but I don't have any extra syringes to pack it into....

Here is a link to a small amount of paste solder....actually enough for quite a large kit....

http://www.zianet.com/erg/ShopSolderPaste.html

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« Reply #93 on: March 05, 2008, 01:53:40 PM »

Attempted repair R-390A i-f output chart...

S meter   Generator   AGC 10   MGC 7    MGC 8   MGC 8-1/2     MGC 9   MGC 10
-113 dBm-43 dBm-85 dBm-71 dBm-62 dBm-37 dBm
-103 dBm-38 dBm-75 dBm-61 dBm-52 dBm-27 dBm
-93 dBm-35 dBm-65 dBm-51 dBm-42 dBm-18 dBm
-83 dBm-31 dBm-56 dBm-41 dBm-32 dBm-8 dBm
S9-73 dBm-29 dBm-45 dBm-31 dBm-22 dBm+3 dBm
S9 +10-63 dBm-27 dBm-34 dBm-21 dBm-11 dBm+10 dBm*
S9 +20-53 dBm-26 dBm-78 dBm-24 dBm-11 dBm-1 dBm+15 dBm*
S9 +30-43 dBm-26 dBm-68 dBm-14 dBm-1 dBm+8 dBm
S9 +40-33 dBm-25 dBm-58 dBm-4 dBm+9 dBm+12 dBm*
S9 +50-23 dBm-24 dBm-48 dBm+7 dBm+12 dBm*+16 dBm*
S9 +60  -13 dBm-22 dBm-32 dBm+12 dBm*+16 dBm*
S9 +70 -3 dBm-22 dBm-2 dBm+16 dBm*

* = gain compression



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flintstone mop
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« Reply #94 on: March 05, 2008, 03:24:15 PM »

I kinda have to go with BEAR and W3JN, John, on the prolific amount of info and responses on the Yahoo about the Soft Rock stuff, but let's cut to the chase.
I noticed that the 40M receiver and Soft Rock Lite I.F.only uses the USB plug for power. How in the world does the info from the board concerning I.F. bandpass and spectral display, for either product, get into the computer through the sound card connection?? The software loaded into the computer has to talk to something to give you control over the RX board or I.F. board.
Am I coming from outer space with my question??
I'm ordering anyway.
Fred
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« Reply #95 on: March 05, 2008, 03:40:55 PM »

DISREGARD my last O.F. post. I have seen the light........Amen brother!!! Can I get a witness.
It is a magical thing done through the I and Q output of the Soft rock board into the sound card and that info is fed to the software for an audio output to the outside world of human ears.
OK FINE

Fred
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Fred KC4MOP
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Are FETs supposed to glow like that?


« Reply #96 on: March 06, 2008, 03:46:59 PM »

Key word there Mack...

CURRENT version...

6 is out 7 is in....


(By the way... if someone just wants the surface mount parts soldered on the boards, and do the through-hole stuff yourself....... PM or email me... )

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« Reply #97 on: March 06, 2008, 04:40:37 PM »

I have a couple SR7s but not crazy about the design because it uses an RC to make the I/Q phase. He did that so it would work up to 10 meters. Flip Flops may not work at 120 MHz with the present oscillator design.
It won't be long until he has a new one. Actually SR6 was one of the longest runs.
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« Reply #98 on: March 08, 2008, 10:03:58 AM »

Frank

I heard somewhere that you came up with another configuration for the input xfmer on the soft rock ( T1)?

G
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« Reply #99 on: March 08, 2008, 12:51:20 PM »

Gary,
For 455 kHz I used a two hole type 73 core with three turns trifilar #30. I think it will have better balance that the low perm core with so many turns on it. I think Jay W1VD did the stock transformer. If we get some dynamic range numbers on the softrock at 455 KHz. We might be able to compare performance. My guess is it won't matter all that much at 455 KHz. but my design takes all of about two minutes to wind. I would use type 43 for use above a couple MHz. My fair-Rite book is at work so can post part numbers Monday.
I'm thinking Tony might come out with a board with a DDS on it. This would eliminate a ton of work on his part. I see a lot of posts on his site talking about different options.
I would love to see him take $50 worth of parts and sell the kit for $100 to get the same performance as a SDR1K. Then sell a few thousand of them. He is a good guy and it would be cool to see him do well. Imagine all the time and effort that goes into his kits to maks a couple bucks each. After that build a transmitter board. 
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