Help with NE602 upconverter

[Adithya Sathyanarayan]

Hi all

I built a 100MHz upconverter(NE602) with the help of george smart's design and NE602 datasheet but I cant receive HF bands at all.

All FM stations are appearing at 9x.x, 19x.x, 29x.x and so on with multiples of 100Mhz. I'm new to all this, so if someone could tell me howto convert the above circuit to work with NE602 would be of great help.

Also im using RTL2382U+R820T tuner.

[jdow]

You need to filter out the FM band at the converter's input. Then you
need to make sure there is no RF leakage in any cable between the
converter and the dongle.

Of course, there are some nice reasons to use a 60 MHz crystal. You get
half the frequency error in the upconversion. And the HF bands neatly
avoid the FM band. You might have problems if there is significant
activity between 60 and 90 MHz. Select a frequency that puts your HF
bands of interest outside of the 70 MHz region if there are strong
70 MHz signals in your area.

{^_^}

On 2014/01/10 19:51, Adithya Sathyanarayan wrote:
> Hi all
>
> I built a 100MHz upconverter(NE602) with the help of george smart's design

> <http://www.george-smart.co.uk/wiki/FunCube_Upconverter> and NE602 datasheet but

> I cant receive HF bands at all.
>
> All FM stations are appearing at 9x.x, 19x.x, 29x.x and so on with multiples of
> 100Mhz. I'm new to all this, so if someone could tell me howto convert the above
> circuit to work with NE602 would be of great help.
>
> Also im using RTL2382U+R820T tuner.
>

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[wa5ngp]

Depending on how close you are to various stations you may be having overload problems with your ne602.  I had considered using one of those but after reading a bit including its app note I became convinced that it was not a good way to go due to dynamic range/overload  issues.  I know its a tempting component with the oscillator and mixer and gain  all in one package.   Google it and you will find discussions about its shortcomings.  I am using one of the mini circuits passive mixers.  Once I got my 5 pole FM filter in place and bumped up my LO from 104 to 109 mhz things got much better.  I also put everything in a small metal box.  Until I did that I had lots of FM stations appearing in various places  blowing other signals  of interest away.

Since I did those things I don't even turn on my ham rig to listen anymore.  I'm using an e4000 tuner but I don't think that matters.

73 don

[jdow]

Really, if you use a decent antenna at HF you do not need any gain. Even
the 6 dB loss (noise figure) of a diode based DBM, is no big deal. At
3.5 MHz when the band is open even a 35 dB noise figure is no problem.
Only at 20 MHz and higher would you gain much benefit from a low gain
preamplifier stage.

{^_^} Joanne/W6MKU

[wa5ngp]

yep, I agree with that, plenty of atmospheric noise up to about 30mhz. so 7db mixer loss is no problem.

[Robert Nickels]

I'm not unbiased on this issue since hundreds of NE-602-based HF
converters have been put into use since my article in QST a year ago,
but there's never been a complaint about "too much gain". The
conversion gain provided by the 602 is actually useful when using
compromise antennas, as most of us do, and re-adjusting the Manual RF
Gain setting is simple enough when needed, such as at night when HF
signals are very strong. I've had one in daily use for well over a
year now with consistently good results, and as long as your keep power
applied even the oscillator stability is good enough to allow listening
to an SSB net every day without retuning.

Despite the ongoing bashing of the NE-602 family, I still find it to be
one of the handiest purpose-built frequency conversion devices ever, and
note that it's still being chosen for new designs, such as the
open-source TenTec Rebel 506 and the very popular new Wouxon X1M HF
transceiver.

73 and happy listening, however you do it!

Bob W9RAN

[jdow]

Do note that I remarked about reasonably good antenna rather than in all
cases. {^_-}

And most hams don't know about natural noise levels at HF. Check out this
article: http://en.wikipedia.org/wiki/Atmospheric_noise

Some bands do get quieter at some times of the day. Typically those times
are when the band is considered to be deader than a rock. Once the band
opens noise levels rise dramatically. Heck, that's a decent indication
that a band is open to somewhere.

{^_^} Joanne

[wa5ngp]

I think its performance may well be very specific usage/location dependent so I shouldn't bash, just repeating what I've read.  I am using one of the passive mixers and run wide open bandwidth with no problems at all so I don't even turn on my ham rig anymore to listen.  However, my situation is unique, I live out in the country with no other transmitters close by so my design is not exposed to extra strong signals except for FM broadcast which I do filter out.

[jdow]

That starts to look like a sad case of extreme overload to me. However,
you could be seeing things like networking over powerlines. Do remember
that at 600 kHz you can overload something with limited dynamic range
with a remarkably poor antenna.

Regarding your layout picture, it could be cleaned up just a little.
Then the performance might improve slightly to dramatically. The picture
reminded me of the old saw, one seen it cannot be unseen.

{o.o}

On 2014/01/16 05:39, Adithya Sathyanarayan wrote:
> I changed the circuit a bit and I received some stations. I figure once I put in
> on PCB and in a box I should be A-ok.
>
> I'm getting a really weird hum so if someone could take a look at my circuit and
> tell what else I can do I'd be grateful.
>
> [Imgur](http://i.imgur.com/2UMVYsE)
> [Imgur](http://i.imgur.com/rNG59si)
>

[Priyasloka Arya]

Hi 

I am not sure if you are following the design mentioned in

 http://www.george-smart.co.uk/wiki/FunCube_Upconverter/  (as you mentioned before)

 What is the design you are following now (later you mentioned you are using some newer design)?

Regards 

Priyasloka Arya 

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[Siegfried Jackstien]

Shileding ... proper ground connections

And ... try to rebuild that with much shorter jumper wires and placing all
parts closer toeach other

Dg9bfc

Sigi

Ps results on a real pcb should be better

> -----Ursprüngliche Nachricht-----
> Von: ultra-c...@googlegroups.com [mailto:ultra-cheap-
> s...@googlegroups.com] Im Auftrag von Adithya Sathyanarayan
> Gesendet: Donnerstag, 16. Januar 2014 13:40
> An: ultra-c...@googlegroups.com
> Betreff: [ultra-cheap-sdr] Re: Help with NE602 upconverter

>
> I changed the circuit a bit and I received some stations. I figure once I
> put in on PCB and in a box I should be A-ok.
>
> I'm getting a really weird hum so if someone could take a look at my
> circuit and tell what else I can do I'd be grateful.
>
> [Imgur](http://i.imgur.com/2UMVYsE)
> [Imgur](http://i.imgur.com/rNG59si)
>
>
> --
> You received this message because you are subscribed to the Google Groups
> "Ultra Cheap SDR" group.
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[ashok shankar das]

Adizz,
The signal The big hump seems to be an FM signal. Can you confirm that you are very near to any FM transmitter or your antenna is near any Cable TV cable?