What is the best place to find new Gunn diodes?

[Marco]

Have you seen JBeale's threads and the links therein? There's a lot of cheap modules coming out of China at the moment working at the mmWave ISM bands.

https://www.eevblog.com/forum/chat/opinions-on-reasonably-cheap-mmwave-radar-module/msg3565114/
https://www.eevblog.com/forum/projects/another-small-cheap-24ghz-doppler-radar-but-more-feature-full/

[Ben321]

Have you seen JBeale's threads and the links therein? There's a lot of cheap modules coming out of China at the moment working at the mmWave ISM bands.

https://www.eevblog.com/forum/chat/opinions-on-reasonably-cheap-mmwave-radar-module/msg3565114/
https://www.eevblog.com/forum/projects/another-small-cheap-24ghz-doppler-radar-but-more-feature-full/

Unfortunately those transmitters you linked to threads about all are in the 24GHz band. I'm specifically looking for a transmitter between 10.7GHz and 11.7GHz, due to my intended setup on the receiving end.

[LaserSteve]

OK, having checked Ebay for Microwave Oscillator, there are plenty ol units for 10700 or thereabouts.  Bricks tune up or down in around 80-120 Mhz steps, depending on the crystal installed or in some cases an external reference input.  My bricks for example tune in 106.5 Mhz steps.  Pyro-Joe can certainly sell you a brick with a commercial band crystal in it and retuned for 10.7 or up. All he has to do is retune the ones he tuned for the ham band back to commercial band.

SEE ATTACHED PAPERS FOR MECHANICAL DESIGN:

Try this search you will be pleasantly surprised:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=gunn+diode+x-band&_sacat=0

5 sellers...

Oh Canada, Thy New and Glorious Land, These need a sheet metal iris made from 0.040" brass added, and away you go...

https://www.ebay.com/itm/275495176736?mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=5338722076&customid=&toolid=10050

These are shockingly accurate, Add WR90 detector, this is the microwave version of a Grid Dip Meter:

https://www.ebay.com/itm/114835730792?epid=1917956329&hash=item1abcbe3168:g:-U0AAOSwjJxguAAN&amdata=enc%3AAQAHAAAAsG0TKp02fqXzRw4yopxKkivdVLCrPSMtYdzkDp3Vrwnw4iuV7TYv1uxFtzMAi7mrwby%2BnHrwqUmyumL5%2BeoaUrW7twdudbWTIyS8rnMm9A7f%2FPzaeAym14N%2FEtpRreTVnBC%2FkvNeV4%2FP1PI2%2BCAT5fJ8hxAfxH1V4U7f7akagtxiguHFM9nPzWLhNoU5e7jxolUI%2BN7CnjQi43mzy03nqQwXqrtrirj%2FRGzXdTSMdKtk%7Ctkp%3ABk9SR4zc1bKJYQ

Unless your "treez|", you should be delighted.

Something Russian:



Overkill:



FM Video TX:



Totally Daz-eling...



Revenge of the Wavemeter:



See attached PAPERS

Good tutorial:





Steve

[buta]

I'm specifically looking for a transmitter between 10.7GHz and 11.7GHz, due to my intended setup on the receiving end.

Not sure your area uses Ku band for satellite TV or not.
IF your area uses Ku band for satellite TV, do you allow to transmit in 10.7 GHz to 11.7 GHz?

[Ben321]

I'm specifically looking for a transmitter between 10.7GHz and 11.7GHz, due to my intended setup on the receiving end.

Not sure your area uses Ku band for satellite TV or not.
IF your area uses Ku band for satellite TV, do you allow to transmit in 10.7 GHz to 11.7 GHz?

I live in the US. Here, we don't have free-to-air satellite TV. In the US, satellite is all paid TV. And to avoid being able to be illegally received/pirated using standard free-to-air satellite LNBs, paid satellite TV signals are transmitted with circular polarization. Normal free-to-air satellite TV (used in some other countries) uses linear polarized LNBs. In both cases, it's in the KU band, but with different polarization, it's unlikely to interfere. Those cheap KU band LNBs you can buy on Amazon or Ebay are linear LNBs for receiving free-to-air satellite signals found elsewhere in the world, but in the US, they serve very little practical use.

However they can be used for a very cheap microwave receiver for experiments, provided that you also have a signal source that operates in the same frequency. And that's the hard part, is getting a transmitter for this frequency band. KU band LNBs typically operate in one of 2 polarizations, horizontal and vertical, which is selected by the voltage used to power the device. If you power it at 12V you get one polarization. If you power it at 18V you get polarization 90deg to what you get at 12V. This is to prevent needing to manually rotate the LNB by 90 deg to switch polarization. The frequency band is selected by the presence (or lack of presence) of a 22kHz tone. Without the tone, the KU low band is used, between about 10.7GHz and 11.7GHz. With the tone, the frequency band you get is the KU high band, between about 11.7GHz and 12.7GHz. The specs for the tone is a 1Vp-p 22kHz square wave.

For simplicity of setup, I'm not going to figure out how to inject this audio tone onto the coax. It's going to be difficult enough to build a Bias-T adapter to inject DC power on the coax, and then extract the RF off of the coax. So without the tone, I'm limited to receiving the KU low band between 10.7GHz and 11.7KHz.

Now with that in mind, I'm going to just need to figure out how to generate a microwave signal within the range of 10.7GHz and 11.7GHz, so that it will be receivable by a cheap KU band linear LNB that I can buy on Amazon.

[james_s]

Unfortunately those are listed as new-old-stock. Does nobody make gunn diodes anymore? Has some new technology been introduced that fills the same role, that I'm not aware of?

So? What's wrong with new old stock? They don't expire.

[ejeffrey]

I live in the US. Here, we don't have free-to-air satellite TV. In the US, satellite is all paid TV. And to avoid being able to be illegally received/pirated using standard free-to-air satellite LNBs, paid satellite TV signals are transmitted with circular polarization. Normal free-to-air satellite TV (used in some other countries) uses linear polarized LNBs. In both cases, it's in the KU band, but with different polarization, it's unlikely to interfere.

Circular polarization overlaps 50% with linear and will definitely cause interference with only 3dB rejection.   Polarization is also not really a means of piracy prevention, it's mostly chosen for transmission and scattering characteristics.  Afaik all current paid satellite TV is digital and encrypted, but older analog systems used scrambling.  The only way circular polarization could be considered to prevent reception by unapproved devices is that most satellite transmissions use both polarizations for different channels.  A linearly polarized receiver will see both equally and possibly be unable to resolve either.  But that only works because the signals are close to the same strength due to originating at the same transmitter and following the same path.