Sourcing Gunnplexers - Page 1
Forum section: electronics / rf-microwave

author: galvanix
author_rank: Contributor
timestamp: September 11, 2016, 05:54:13 pm
content: Hi!I've been looking around the german eBay site for gunnplexers for some radar experimnets but couldn't find any. Does anyone here know of sources for gunnplexers in Germany other than eBay?Thanks!galvanix

author: cj
author_rank: Contributor
timestamp: September 12, 2016, 06:47:10 am
content: Helmut Singer in Aachen sells a 24GHz Doppler module (KDM24T) which basically is a gunnplexer.These are salvaged units.http://www.helmut-singer.de/CJ

author: galvanix
author_rank: Contributor
timestamp: September 12, 2016, 04:20:13 pm
content: Thanks I'll have a look at those!Do you know of any other sources for X-Band gunnplexers?

author: cj
author_rank: Contributor
timestamp: September 13, 2016, 06:53:40 am
content: Sorry I don’t know anyone who supplies X-band gunnplexers in Germany or the Netherlands.You can find X-band gunnplexers, including a small horn antenna, in old door opening sensors.The gunn-diodes in these sensors are a worry. These sensors where often used 247 for years so the condition of the gunn-diodes is an unknown. They might be good, dead or near death you just don’t know.Sometimes you can find X-band gunnplexers at radio amateur flea markets but they are becoming rare.CJCJ

author: LaserSteve
author_rank: Super Contributor
timestamp: September 13, 2016, 04:32:23 pm
content: Gunnplexers have been replaced by 10 Ghz DRO boards with integral patch antennas. These sell for 5-15$ on Ebay...www.SHFMICRO.comis a source of Gunn diodes if you wish to make your own cavities and horns. Click on "Diode" on his page.There is a major ham radio supplier in Italy who always has some X-Band Gunn diodes as well. I just cant remember his company name.Steve

author: RFMWdude
author_rank: Contributor
timestamp: September 13, 2016, 04:41:24 pm
content: Quote from: LaserSteve on September 13, 2016, 04:32:23 pmYou were probably thinking of Franco Rota,http://www.rf-microwave.com

author: galvanix
author_rank: Contributor
timestamp: September 13, 2016, 05:08:11 pm
content: QuoteYeah I've seen those, they seem to be fixed frequency i.e. doppler radar which only detects moving objects. My goal was to use a gunnplexer for FMCW, I'm not sure these modules lend themselves to being frequency modulated (although I have no experience with DROs).Do you think those DRO boards can be tuned like a VCO?Thanks!galvanix

author: LaserSteve
author_rank: Super Contributor
timestamp: September 13, 2016, 06:42:28 pm
content: They are somewhat voltage sensitive and with the addition of a simple Varactor could be FM modulated. I have not measured the tuning range with respect to voltage, but my example is mechanically tuned by a set screw over a wide range of 500 Mhz.Steve

author: LaserSteve
author_rank: Super Contributor
timestamp: September 13, 2016, 06:44:16 pm
content: There are also lots of surplus YIG oscillators on Ebay...Steve

author: cj
author_rank: Contributor
timestamp: September 14, 2016, 05:26:29 am
content: If you want to do FMCW the 24GHz units from Helmut Singer and gunnplexers from door opening sensor are no good they don’t have a varactor.Gunnplexers with varactor diodes can tune about 50MHz to 100MHz but output power will vary significantly and tuning is non linear. Also the detector bias varies significantly with tuning.Like Steve suggested YIG oscillators are a good option.CJ

author: 1design
author_rank: Regular Contributor
timestamp: September 15, 2016, 02:31:48 pm
content: Isn't it easier to just use one IC?BGT 24LTR11N16 E6327BR

author: galvanix
author_rank: Contributor
timestamp: September 15, 2016, 05:41:57 pm
content: Quote from: 1design on September 15, 2016, 02:31:48 pmMost likely easier and better performing but not as much fun

author: KE5FX
author_rank: Super Contributor
timestamp: September 18, 2016, 07:06:16 am
content: Quote from: LaserSteve on September 13, 2016, 06:42:28 pmTheir voltage sensitivity is substantial. Years ago I built a 10 Mb Ethernet link with a couple of varactor-tuned X-band Gunnplexers from shfmicro.com, and another fellow (K3PGP) did something similar with cheaper motion-detector transceivers that didn't have a varactor at all.Now that I think about it, Glenn Elmore's original 2 Mbit link project also used power-supply modulation.

author: Fraser
author_rank: Super Contributor
timestamp: September 18, 2016, 08:49:11 am
content: I have a box of high quality Racal 10GHz intruder detection sensors. They are superb build quality and contain a cast TX and RX horn assembly. The TX horn has a deliberate RF leak through to the RX horn. They use quality Gunn cartridge type diodes. They are brand new, so no hours on them.I was going to put them on eBay and see what I can get for them. I can upload pictures and details if anyone is interested. They were a very expensive detector in their day. Happy to consider offers for them, individually, or the whole lot. I will have to count how many I have as some in the box will be IR types.I am located in the UK amd will ship overseas.Fraser

author: LaserSteve
author_rank: Super Contributor
timestamp: September 19, 2016, 03:45:03 pm
content: Quote from: KE5FX on September 18, 2016, 07:06:16 amI WAS referring to the DRO board, I know Gunn Diodes wander all over the place.Steve