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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 80079 times)
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KF1Z
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Are FETs supposed to glow like that?


« Reply #25 on: February 16, 2008, 12:22:48 PM »

Hmm, a simple DC receiver for 75M shouldn't be too hard to build for use with the Softrock Lite.

- JT

The softrock lite IS a DC RX!

Just order the 80 meter version, and change the crystal to where you want to receive.


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N1ESE
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« Reply #26 on: February 16, 2008, 12:34:27 PM »

The softrock lite IS a DC RX!
Just order the 80 meter version, and change the crystal to where you want to receive.
Yeah, call me stupid (as usual lately).  I don't know what I was trying to say there.
 
Ordering a couple softrocks today.

- JT
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KF1Z
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Are FETs supposed to glow like that?


« Reply #27 on: February 16, 2008, 12:48:46 PM »

Although changing the crystals to 15.36 MHz crystals should, when divided by 4, give a center frequency of about 3.84 MHz. 

- JT

You can use x4, or x8... there is a jumper on the board to use either....

Remember, the exact center frequency is unusable ... you want to shoot for about 5kc or so higher, or lower....

If you have a soundcard that samples at 96khz,  you have an available tuning range of just under 48khz.... if a 48khz soundcard... only 24khz of tuning range...

So if you're shooting for the 'ghetto',  you want a center freq of say...3.870.

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N1ESE
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« Reply #28 on: February 16, 2008, 01:12:41 PM »

So if you're shooting for the 'ghetto',  you want a center freq of say...3.870.
Good point about the center frequency not being usable.  I have some 30 MHz crystals which would give me a center of around 3.875.  On the 40M kit, I assume I'd want a center frequency to be around 7.265 - 7.270?

Thanks

- JT
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KF1Z
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Are FETs supposed to glow like that?


« Reply #29 on: February 16, 2008, 01:18:53 PM »

So if you're shooting for the 'ghetto',  you want a center freq of say...3.870.
Good point about the center frequency not being usable.  I have some 30 MHz crystals which would give me a center of around 3.875.  On the 40M kit, I assume I'd want a center frequency to be around 7.265 - 7.270?

Thanks

- JT

Something like that.......

A 30mhz xtal would give you 3.750 though
A 31mhz would give a center freq of 3.875

You could just order the RX/TX kit for 40 and 80...
Even if you don't plan to use the TX section.... you'd have 2 bands in one board...

Though I thinks it's actually cheaper to build the separate receivers...
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N1ESE
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« Reply #30 on: February 16, 2008, 01:29:32 PM »

You could just order the RX/TX kit for 40 and 80...
Even if you don't plan to use the TX section.... you'd have 2 bands in one board...
Though I thinks it's actually cheaper to build the separate receivers...
Yeah, the 40/80 RX/TX kit is only $30.  I was thinking of getting a 40/30 RX/TX in addition to the 80 RX but maybe I'll just get an 80/40 RX/TX to play with for now.

- JT
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #31 on: February 16, 2008, 02:02:14 PM »

Ok, well I am a bit slow on the uptake here.

In the case of using it for ONLY a 455kc or in my case 500kc IF - you'd want a crystal that is 4x that freq, or for the 500kc.; that would be a 2khz xtal??

But what is this about it not working on the center freq??

Guess this is my main interest, using it  coming off the IF of my BC-388.
Am I correct, it does do "sync" detection and USB/LSB then??

Now, what is the purpose of the soundcard in all of this??

That's unclear to me so far (would be nice if there was a concise rundown on it)?

            _-_-bear
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_-_- bear WB2GCR                   http://www.bearlabs.com
WA1GFZ
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« Reply #32 on: February 16, 2008, 02:13:31 PM »

WOW, now that SDR is cool you guys will find out the softrock has all the receiver performance of the SDR1k.
Gary your signal into the softrock board is pretty high, it will limit your dynamic range. Every receiver IF level is different so Tony has no way of knowing how to set up the board. He sets it up for use as a receiver hanging off an antenna. Your noise floor should sit around -120 dBM to get the full dynamic range of the board.
Your floor is 40 dB above that so you are losing that much dynamic range. There are a couple ways to set this properly. 1. Reduce the op amp gain. 2. reduce the signal level into the board. 3. Set your sound card inputs lower. I'm not sure if the 390 has enough dynamic range to just reduce the RF gain but that would be the easiest way. The Flex software has a very accurate S meter so if you can run in manual gain mode and calibrate the s meter you will have quite a nice tool. This will also serve as a great spectrum monitor with the very clean R390 LO.
I built a fixed gain front end with Racal RA6830 and RA6840 DF modules into the QSD. Then I calibrated the system to track the output of a HP8640B within 1 dB.  
You know when you are in overload when all of a sudden you have a spurs across the spectrum.
I2PHD software is also very cool. Alberto has a cool phase meter for sync detect AM that shows phase modulation and slow drift very well.
Stepping into 2008 HPSDR (TAPR) is now taking orders on the exciter module. 1/2 watt output with third order crud down over 50 dB.
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W2INR
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« Reply #33 on: February 16, 2008, 02:54:38 PM »

Thanks Frank ,

I am in the beginning of the learning curve with this stuff. All of my help came from Bill KA8WTK with the SR and Jay N3WWL with the SDR software to get me started.

I installed a 5:1 pad and it knocked down the IF input signal to about -120dbm noise floor going into the SR board.
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G - The INR

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KF1Z
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Are FETs supposed to glow like that?


« Reply #34 on: February 16, 2008, 03:56:52 PM »

Ok, well I am a bit slow on the uptake here.

In the case of using it for ONLY a 455kc or in my case 500kc IF - you'd want a crystal that is 4x that freq, or for the 500kc.; that would be a 2khz xtal??

But what is this about it not working on the center freq??

Guess this is my main interest, using it  coming off the IF of my BC-388.
Am I correct, it does do "sync" detection and USB/LSB then??

Now, what is the purpose of the soundcard in all of this??

That's unclear to me so far (would be nice if there was a concise rundown on it)?

            _-_-bear


Bear,
It might be easier to get all the info you're looking for on the sites listed above.

There's a few reasons that the center frequency is unuseable....too many to discuss here...

In most cases, it isn't even a problem, and can be eliminated ....


The soundcard is used to get the I/Q signals into the computer for processing... and, obviously a way for the audio to get out to speakers....

For the xtal... yes... choose a crystal that is either 4x or 8x your IF... plus or minus about 10kc... to avoid any possibly "center frequency problems"
(shoot for 490khz center).

Tony supplies a 3.56mhz rock with his 455khz IF kits





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WBear2GCR
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« Reply #35 on: February 16, 2008, 05:42:03 PM »

Well, I've looked at the sites... I'd rather not spend the time to read through the blogs and all the posts to get at the essence of the set up to decide if it is something that I'm interested in spending any time working with...

Guess I'll try the yahoo site and hope they've put up some basic info off to the side...

               _-_-WobblyBear2GCR
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W2INR
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« Reply #36 on: February 16, 2008, 05:52:35 PM »

Bear

I wish I understood this stuff better to help you out but I don't .

In fact all I did was order one, build it, plug the audio cable into my sound card . plug the IF from the r390a into the SR and apply 9 volts power. Then I downloaded the SDR software, set it up and bang it worked. That is all I know. I have no clue as to how it works and I could care less.

Buy it, Build it, play with it, and then you will know, its only $12.00 bucks Bear.

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G - The INR

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N1ESE
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« Reply #37 on: February 16, 2008, 05:55:48 PM »

Heh, gotta love INR's style..

- JT
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N1ESE
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« Reply #38 on: February 16, 2008, 06:01:12 PM »

And definitely don't delve too deeply into the I&Q (in phase & quadrature) signals. That stuff will give you a headache fast.
Yeah, no matter what your IQ is!  Shocked
 
- JT
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N1ESE
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« Reply #39 on: February 16, 2008, 06:18:13 PM »

VGB: Or just learn how to setup filtering in your existing email client.  I use one email client for all my emailing and probably receive close to 500 emails/day.  When, for example, an email comes in from the AM Reflector it automatically gets moved from the inbox and into its own folder.  I then scan the subject headings and read those I want to read.  When I am done reading, I click all off them and say "mark as read".  I can then archive all emails this way if I ever need to go back and look something up.  I may get 500 or more emails a day but it is actually very quick and easy to read and manage.
 
- JT
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N1ESE
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« Reply #40 on: February 16, 2008, 06:19:34 PM »

KF1Z - YahooGroups is the same thing as an email reflector.. it just allows you the choice of reading it online or having it sent by email.  I prefer email lists myself.
 
- JT
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N1ESE
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« Reply #41 on: February 16, 2008, 06:45:15 PM »

Yup, to each his own exactly.  Email is second nature to me as I've had to administer large email systems, and reflectors, in the past as a career and I've also been subscribing to reflectors long before there was the ability to read them via a web browser.  But I guess we are now really getting off-topic.
 
- JT
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N1ESE
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« Reply #42 on: February 16, 2008, 07:59:06 PM »

The BEAR has come out of the woods and just posted to the softrock40 group. Cheesy 


(Yes, I am easily amused tonight)

- JT
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W2INR
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« Reply #43 on: February 16, 2008, 08:02:44 PM »

Hey

Hijack someone else's thread.

Thank you

G
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G - The INR

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« Reply #44 on: February 16, 2008, 08:16:20 PM »

Not many Mack, just those that people allow to go off topic.

I just felt talking about yahoo groups was far from the original topic.

G
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G - The INR

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WA1GFZ
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« Reply #45 on: February 16, 2008, 09:15:43 PM »

The reality of softrock is the performance is very good. It has a crystal oscillator as a source which is cleaner than any synthesizer or DDS source. I have done a number of tests on the stand alone QSD. It's performance is better than anything in my shack. It is a cleaner spectrum analyzer than my hP141. The only problem is that it is only a small part of the spectrum.
I got real interested in SDR just after Tony sold his last softrock  4. a friend who bought a Racal from me in Ca. offered to do the drafting and artwork if I designed a QSD.  I did a converter very similar to the SDr1K RX and the oscillator divider similar to softrock. We made it a plug in module for the RA6830. It cost us over $200 and plenty of labor to duplicate 2 softrock 6s.
The performance limit of this stuff is overload. Any signal that gets into the QSD  is processed. If the level saturates the sound card you are all done. This is why hanging off the IF of a good RX with limited bandwidth is the best of both worlds until the dynamic range of A/Ds gets better.
The third generation stuff is just hitting the ham market. The QSD and local oscillator is completely eliminated by sampling the spectrum with a very fast A/D. Again the wide bandwidth of the system makes it susceptable to overload but great hanging off a good RX IF.
Steve HUZ  posted a link to a great SDR article a few weeks ago. This is great reading. A bit dated with older parts but source of understanding. I suggest reading it cover to cover about 10 times.
Pete WA1SOV got me interested in this stuff almost 8 years ago before the days of doing this with a computer sound card...Later some creative software guy figured out how to make the stereo input handle I/Q decode.
Gary, Now that you have your level right how about a picture of a real strong crystal oscillator. I would like to see the effects of the very clean LO in the R390.
I bet the performance could be impressive if the 390 has enough dynamic range.
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K9ACT
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« Reply #46 on: February 16, 2008, 10:54:32 PM »

I just finished  building a SoftRock 80/40 transceiver which does not work and  browsed this thread missing the whole point of it.  A QSO this evening with KAQ set off the light bulb in my brain.  My only reason for building this thing was to get a panaramic spectrum analyzer to study incoming signals.  I couldn't care less about transmitting.

I sent mine off to a friend who built one that works to see if he can fix it but now it is obvious that it's the wrong tool for the job.  Being xtal controlled, it's use is really limited to a learning experience.

The idea of setting it up to the IF freq of a receiver for complete coverage really gets me excited.

Is there any reason why this would not work on my S40B?  Or the S38 for that matter?

Where would be the best place to pick up the signal on the S40B?

For the record, the problem with the one I built is excessive current drain on the 5V side of the regulator.  My thinking is one of the IC's  is bad but I lost interest when it came to proving this.

js
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KA1ZGC
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« Reply #47 on: February 17, 2008, 12:57:14 AM »

HAY, GEE...

NOW YOU GOTSA REEL RESEEVA, THAT MEEN YOO AINTS GUNNA CALL MI QWARTER KILAWHAT PISWEEEK?

UH.... OVA!

BIFF
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W2INR
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« Reply #48 on: February 17, 2008, 07:36:57 AM »

Jack.

No you didn't miss the point and I started this thread yesterday morning.

The answer to your question is yes. All you need to do is figure our what the IF frequency is where you want to pull off the receiver and then email Tony.

G

Did I here Thom in here?
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G - The INR

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« Reply #49 on: February 17, 2008, 08:09:45 AM »

Frank

I installed a 20db pad in the IF line and I have the noise floor knocked down  pretty good.

Below is a screen capture of the SR with the calibrator on in the R390a.


* sr20dbpad.JPG (162.56 KB, 1029x771 - viewed 624 times.)
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G - The INR

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