Basic Jupiter/Solar radio astronomy

[geppetto]

The idea is that using a fairly simple receiver design and a half wave dipole for an aerial, radio noise can be monitored from Jupiter and from the sun.

A typical frequency used is 20.1Mhz which is one of the rare quieter areas of the radio spectrum.

I sourced a simple kit which could be modified to operate on this frequency and decided I would keep a log on here of all the ups downs and otherwise of the project.

The kit is a Ten-tec 1056 direct conversion receiver which is a good base from which to start.

First off was an aerial and at half wave, this turned out to be two wires, 11' 8.4" in length with a coax cable at the centre point to feed the receiver.

Not as ideal as outside but I fitted one along the inside of my bungalow roof for convenience.

More to follow with pictures of the receiver build and details of the mods that will need to be done.

[geppetto]

Some pictures of the receiver during the build.

As you can see, it's very basic but should do the job with some mods

and tweaks...

Good quality PCB and components and fool proof instructions...

It worked fine during testing on the nearest ham band...

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More later...

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These are circuits for addons to the basic receiver...

They will need printed circuit boards making and building from scratch...

Be nice to get the PCB etching stuff out again, it's been ages...

First circuit is a tuned RF amplifier.

This goes between the receiver and the aerial to boost the wanted frequencies. Might need two of these...

Second is a narrow band filter to accept the wanted frequencies and to cut back unwanted stuff.

This will be lossy hence the possible need for a second amplifier.

This will fit between the first amplifier and the receiver or at the aerial, not decided yet.

[geppetto]

A bit about the frequency coverage of this kit receiver...

Cleverly, they've included the necessary coils and capacitors to cover the

poular shortwave amateur radio bands and you choose which band at

the build stage and fit the required components..

The sheet below shows the bands in the left column and the respective

components from C1 to L3 across the page.

The nearest band to 20.1Mhz is the 15 meter band at around 21Mhz.

The coils and capacitors were chosen for this band but I have substituted

two 47pf capacitors (C1 and C3) with 56pf capacitors.

Bit of a guestimation but I reckon this should pull the frequency down to

nearer the 20Mhz region....

I did give it a run with the components in for 40meters, a very active band

with lots of ham radio stations using morse and single sideband transmissions..

It proved the kit worked and it gave me some morse code reading practice as well. Got a bit rusty over these past few years :mrgreen:

Anyhoo, click on the video with sound below ....

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Bit more done

Wound the coils for the rf amplifier and the band pass filter

The idea is that the bandpass filter offers a narrow window to frequencies that it's tuned to,

thereby rejecting a lot of unwanted interfering signals either side of the wanted frequency.

Looks a bit crude this method of construction but it's easy to do by Dremeling

away the copper in a groove around each component pad.

Leaving 99% of the copper as an earth plane is good for stability at higher

frequencies....

Soon as the bits arrive, I'll fit the other components to this unit.

The whole thing will then be wired between the aerial and the receiver

aerial input.

I've left enough copper space to fit a second rf amplifier at the right hand end of the board

incase the losses within the filter are too large and the signal will then need a second boost

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Last bit for today, Mrs Geppetto wants here table back for tea...

Bit unreasonable but what can you do

Little audio device to interface between the receiver and the computer

sound card input (line in)

The second transistor rectifies the audio so that a signal level meter can

be added.

Very handy when first tweaking starts....

Built on strip board, hate the stuff but me etching fluid has gone off so

no proper printed circuit boards today

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Just done a rough test of the audio into the lappy for a quick check...

Set skypipe charting software running (not set up properly yet)

and charted the back ground noise from the unfiltered receiver.

The large spikes were produced by clicking a pizo gas lighter near to it as

those things kick out a hell of a pulse and make a great "poor man's"

noise generator :mrgreen:

Anyhoo, all seems to be working so waiting now for delivery of a few more

components to finish the RF filter/amplifier

[geppetto]

Still waiting for bits to come in the post so no construction done today.

Gave me chance to get fully to grips with the charting software called Skypipe

Radio-SkyPipe Strip Chart Program

My brains getting older and it's taking me longer to sort new software out but I've got the hang of calibrating it and setting the chart levels so quite pleased with how it works...

Idea is, that you feed the audio from the receiver into the "mic" or "line in" of your computer and the sound card does the analogue to digital conversion, the values of each sample being drawn on a live scrolling chart by Skypipe.

Having calibrated it such that the back ground noise is the base level of the chart, then any crackles or whooshes from the sun or jupiter will trace a plot on the graph against an accurate time marker.

On the to do list, is to build a few items of test gear. I gave away my service gear when I had to give up the service engineer life due to major back problems...

Anyhoo, on the list will be a frequency meter, a noise generator and an RF signal generator to make construction of any more of this radio stuff easier..

More later as this unfolds but up to now it's looking good

[geppetto]

Bit more messing about today...

Tidied some wires up and stuff but the main job was taking a look at the audio low pass filter.

These direct conversion receivers take a signal from the aerial and mix that with a tuning frequency.

The difference between these two is audio hence the simplicity of it.

All the amplification is then done at audio levels and this is where the low pass filters go.

The basic receiver is designed for CW and SSB reception so the filter is quite tight to keep the noise down.

It does this very well but it looses too much of the back ground noise for this astronomy application...

Anyhoo, I fitted a switch which selects normal narrow band in one direction and wider (using a resistor and capacitor) in the other.

This really opens up the receiver to better noise reception meaning Jupiter crackles will be louder

This is the setup so far doing a plotting test and my astro puter set up and calibrated.

You can see the bottom line normal noise threshold and the traces from arcs and sparks produced by my pizo lighter flicker

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Test gear building today..

Last week I sent for a frequency counter kit from USA and it turned up this

morning so I built it up...

Not strictly a necessary item for this Jupiter/sun receiver project but it's handy to prove it's on 20.1 Mhz which the counter shows it is by sampling the receiver's variable frequency oscillator.

I've really enjoyed getting the soldering iron out again so I'm going to make a low power CW transceiver to get back for a play at Ham radio and this will be a very useful bit of test gear for that as well...

Absolute bargain I reckon for less than £20.00

Not too bad to put together if you take care and thanks to Doug for his great prices and great service....

N3ZI Digital Dial with universal LCD interface

Still waiting for components to finish the receiver so more later

[geppetto]

Some more done...

Components turned up so I was able to get cracking with the RF amp/filter board...

Usual fair amount of tweaking values to get the thing working right but all

is OK. The RF pre amp really opens up the sensitivity of the receiver and

makes up for the losses in the filter.

After much tweaking, I got the filter as wanted with a nice cut off either side

of the wanted frequency..

The little board in progress near the pair of cutters will be a buffer amplifier

for the frequency counter so it will work without having a de tuning effect

on the receiver......

Next step is to start fitting it all into an aluminium case so it's tidy and

screened...

Onwards and upwards

[geppetto]

Shocking weather today so a good excuse to carry on with the project...

Finished the frequency counter buffer amplifier board and as hoped, this

has minimised any detuning effects of sampling the receiver's frequency..

Started the case so I can get everything tidied away for final tweaking

and modding..

Plenty of room for a fully regulated power supply and a few other bits

that I fancy adding at a later date....

More later

[geppetto]

Speaker is fitted, looking the dogs danglies now I reckon

That's it for today as me back is screaming

Having some great fun lashing this doodah together

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Been wiring the boards together now they are in the case...

Some final tweaks and the frequency counter is working great. That will go in it's own case as it's a useful bit of test gear...

Next step (when me back has calmed down a bit) will be a mains power supply.

That will have to be well regulated and fairly noise free so a bit of digging around in me spares box for some bits for that...

Took a mini video of the puter screen running the Skypipe charting software whilst moving the tuning knob in and out of a signal...

You can see the jumps in the vertical axis corresponding to the blips in audio level...

This is basically what the Jupiter/sun noise will cause the chart to do...

Click to run with sound

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Next little tweak

Still not quite happy with the audio filter so I'm going to make a filter based

on the one used in the Jove receiver..

This uses coils and capacitors so in theory it should provide a better shaped

low pass filter...

Hopefully will try it out later

[geppetto]

Right, that's in and well worth the effort...

It's cut down the unwanted higher hissy frequencies and produced a much rounder tone.

It should help to clear some unnecessary stuff from the graph plots

Next step will be to swap out the couple of capacitors that determine the frequency of the receiver for higher stability types to help minimise tuner drift.

Then, on to the power supply...

Nearly there

[geppetto]

ery bad back pain today so trapped indoors under the influence of drugs :mrgreen:

Got bored so I thought Id make a little noise generator.

These things generate white noise over a large range of the spectrum.

Idea is that to calibrate the receiver to the charting software, you need a standard stable source of radio noise and this is what it does....

Another side use, is to plug it into the receiver and use Spectrum Lab software to look at the audio out frequency scale.

Now, the Jove receiver write up says that the low pass audio filter in their design passes low frequencies up to about 3KHz then it rolls of, cutting the unwanted higher frequencies...

Since I "pinched" their filter design and stuck one in my receiver, I decided to check it's response...

The graph plotted by Spectrum lab shown below clearly shows the roll off point at around 3KHz.

So it works..... I knew it did but I was bored so I set about proving it :mrgreen:

Drug induced waffle over

[geppetto]

Another bit added...

This isn't totally necessary but since I may be trying more of these receiver designs, It's useful...

It's a 20MHz source using a cheap crystal oscillator capsule that is very stable in frequency...

Very handy as a known RF source for tuning the receiver as it is just below

the 20.1 that I'm listening on....

Sorry it's ugly but it works....

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Not much done this last 24 hours as I'm laid out again with back pains

Anyhoo, the last of the bits should be here tomorrow from Maplin so the receiver should be finished very soon, back willing...

Here's a picture of the machine with it's top on....

Looks quite smart and it's not as big as this picture makes it out to be..

It's 11" wide by 8" deep by 4" high...

Spent some down time reading up on stuff for the next astro receiver which

I'll start whilst the tools are out... more on that later...

[geppetto]

Another little chunk put in today....

Not much as the "nurse" is only allocating short play times

Anyhoo, a four way switch fitted to the back of the receiver.

It switches the receiver aerial input to 1: the aerial socket 2: a 50 ohm dummy load 3: the noise generator and 4: the 20MHz frequency source.

Other contacts on the switch, selectively apply power to the noise generator and the 20MHz OSC where needed...

Idea is that I can have the aerial connected as normal or switched to the dummy load for receiver noise checks or switched to the noise generator for calibrating the receiver to the Skypipe charting software.

The last position, the 20MHz OSC is for checking the receiver is on tune...

More later when nurse ain't watching

[geppetto]

Todays bits....

Decided to run it off a Maplin battery pack to prevent a mains PSU possibly putting noise into the receiver.

So, stuck a 2.1mm socket on the back panel and an obligatory fuse holder.

Stuck a 3.5mm jack socket on the front panel for headphone listening.

Plugging in headphone cuts the speaker.

Wired a 5 volt supply to the frequency counter buffer amplifier board...

Getting really full in there now

Just the high quality frequency determining capacitors to fit (when I've souced some) and that's pretty much job done

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Nearing the end of the project now...

Replaced a couple of tuning capacitors with high grade ones which has

improved the thermal frequency stability.

Put in a small panel meter to monitor the level of the audio signal.

This means I can keep an eye on signals coming and going by having a

quick peek at the meter when I've got the sound to the speaker turned down.

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Receiver's working fine and all tweaks finished...

Next step is to sort out an aerial outside so that when I'm out with the scope, I can look and listen to the jupiter signals whilst imaging Jupiter at the same time.... that would be cool

At some point, I'll get round to putting up a twin horizontal dipole down the garden but, I'm still in experiment mode :mrgreen: so I'm going to make a large loop with reflector aerial as shown below...

Bit of a big brute with 6' sides but it won't weigh much and it will just slide into my greenhouse (when the tomatoes are out) for storage.

Should be fairly good as it's directional so in a few weeks when Jupiter climbs into my back yard's FOV, I can point directly at the planet...

More as this unfolds

[Supay]

This thread is fantastic and has really gotten me wanting to tinker! I don't really have any knowledge of electronics, although I imagine I could do if I put my mind to it. This looks like exactly the fun kind of project I like and you've given me quite a chunk of inspiration to have a go myself and see what I can do.

Great work!