VK Logger Ham Radio Forum Archive

We arent tearing them apart, but using them whole Tim. They are great receivers.
10 and 24GHz, and so cheap too. Add a 4 cell lipo pack and you have a great sniffer rx. Add a switch to change it from sweep to a pot to adjust rx freq, a small amp and speaker etc
73 Dave

VK2JDS wrote:We arent tearing them apart, but using them whole Tim. They are great receivers.
10 and 24GHz, and so cheap too. Add a 4 cell lipo pack and you have a great sniffer rx. Add a switch to change it from sweep to a pot to adjust rx freq, a small amp and speaker etc
73 Dave

Oh OK! didn't realize that.. cool

73's

Tim

Wayne

If you are still looking for a Gunn assembly, I checked the junkbox and there are a couple in there that may be good candidates.

i will check them out and pick out the best of the two. Gunn oscillator power levels can be all over the place. I will need to check the Rx diodes are OK too.

if you let me know what frequency you want it on I will set it roughly before sending it to you.

One of the units has a power supply/modulator attached. If it all still works I will draw a circuit for it and leave it all attached.

Cheers

Tim VK5ZT

A 10 GHz Gunnplexer link by W2IOG. Article below.

http://armag.vk6uu.id.au/1978-october-AR.html

A little earlier W5KHT described a video Gunnplexer system.

http://armag.vk6uu.id.au/1978-august-AR.html

Hi Tim

I will drop you an email today. Obviously the microwave community is very helpful and supportive.

If I can get a pair of Gunplexers working it should get more of the locals interested in the band.

Peter, that is a good article.

73

Wayne VK4WDM

No worries Wayne

Also, don't forget there is a huge source of very sensitive receivers for 10 GHz.....satellite LNBs

Not much effort is needed to use an old LNB....the only normal problem is the requirement for a wideband Rx up in the 500 odd MHz region where the IF usually ends up...food for thought.

I'll chuck one in with the Gunn unit along with frequency information re. its use....

Cheers

Tim VK5ZT

requirement for a wideband Rx up in the 500 odd MHz region where the IF usually ends up.

Hi Tim

I do have one of these dongles: Newsky TV28T v2 DVB-T, DAB+, FM, SDR, USB Tuner/Receiver - RTL2832U & R820T 24 MHz to 1.8 GHz.

Could that be used as an IF?

73

Wayne VK4WDM

Hi Wayne

That USB receiver dongle would be perfect.....an added benefit being you could scan looking for the signal! Gunns and to a lesser degree DROs (the LO in an LNB) are susceptible to drift especially due to temp changes so are not always where you think they will be in terms of frequency...

The benefit of one of those dongles is that you can pick any frequency for the IF if using it with a Gunnplexer....provided whoever is at the other end can do the same.

Send me your address details and I will send the Gunn etc. early next week....

Cheers Tim VK5ZT

Firstly I need to learn how to use the dongle

Wayne VK4WDM

I bought one of those Radar Detectors on eBay as mentioned earlier.

It responds to 10 GHz into a small probe waved in front of it with a nice Russian lady warning me and flashing either a K or Ka band indicator. I can't easily generate 24 GHz but I'm guessing that should also produce a response. A Spec An probe up the mouth of the horn produces a sweeping trace (LO) from about 11.5 GHz downwards with a series of narrow sweeps (50 MHz?) followed by some broader sweeps (150 MHz?).

I've pulled it apart and there's a control board that probably does the speaking, plus there's a microwave horn with a (IF?) PCB attached. Opening up the horn (it's screwed together) reveals a teflon-like (RF) PCB with some exotic looking bits and nice silver-plated tracks.

The lead from the IF PCB to the Control PCB has 3 wires marked +12, Gnd and Data. Obviously some processing happens on the IF board.

Unfortunately, the RF (teflon) board has two sets of 3 pins soldered through to the IF board. The component side of the IF board is not accessible without trying to unsolder these pins - a delicate task.

I'd like to put in manual tuning. Does anyone have any advice on how to go about that? Do I need to unsolder these pins?

Regards,
Dave
VK3HZ

I continue to be very impressed by the microwave community with their helpfulness and willingness to answer some really basic questions.

Thanks to Tim VK5ZT who sent me a complete working Gunnplexer system, and phil VK4CDI who sent me two more that are almost ready to roll, I now have four to experiment with. In addition to that several others have sent me articles and advice.

Hopefully we will have some 10GHZ stations on the air in Townsville for the next field day.

73

Wayne VK4WDM