76 GHz - any interest?

[VK2GG]

Hi all,
I thought it would be good to start a thread on 76ghz. There are a few articles around, mostly in German!
Mixer and IF pcb's are available from Kuhne:
http://www.kuhne-electronic.de/en/products/pcbs.html

Philipp DL2AM has cases and most of the useful components, including hi-performance doublers, mixer diodes, etc:
http://www.dl2am.de/

DL2AM has also an article on a complete transverter, based on DB6NT pcb's, available as download from Kuhne:
http://www.kuhne-electronic.de/en/produ ... -file.html

Matt and I have been discussing the possibility of getting into 76GHz, anyone else interested?

An example of a UK system is here (Chris G8BKE):
http://myweb.tiscali.co.uk/g8bke/sevensixghz.htm

Now, having read some of this material over several months, and translated bits into English, I have some discussion questions:
1/ How are the mixer flip-flop diodes attached to the mixer pcb - bonded or soldered? (They are tiny!)
2/ Using the high performance multiplier CMA382400 into a DB6NT mixer, I can see how Philipp gets the IF from the Tx to the mixer using the 47GHz IF pcb, but what about the connection which usually goes from the Rx IF section of the 47GHz board to the LO doubler? He is not using the doubler, the millicom unit does the multiplying??
3/ Was there a mk I 47ghz pcb from Kuhne which was different from the mk II available on Kuhne's site?

Happy reading, all you 76ghz enthusiasts!!!
Dan VK2GG

[VK2TDN]

flamin' heck Dan

hahahahaa ... let me get my 47GHz sorted out first

speaking of 47 I saw you were thinking of using that on summer fd where to where ??


Dave
VK2TDN

[VK3PF]

Dan,

Diodes are typically bonded using a good quality, fine grain silver loaded epoxy, such as Epotek H2O (IIRC).

Somewhere I have a pair of Kuhne mixer boards, but no cases in which to mount them.

Too many other things on the "to do" list - first priority is to get a new shack established, then a Nally planted in the yard. Also high up will be checking the existing transverters so that I might be able to get out for a few hours on the Summer FD weekend.

Cheers,

Peter

[VK2GG]

Thanks Peter & Dave,
Dave might be Carlingford to Carlingford on 47???
Dan

[VK4WDM]

76GHZ! How do you get your underpants tight enough to reach that frequency? I can only struggle up to 1.2 gigs without busting the elastic!

Good luck!

Wayne VK4WDM

[VK2GG]

Well, here I go!
I have ordered some boxes, diodes, mixer pcb's and a pair of Kuhne pll oscillators. Now to get some sort of rf output, and then get some waveguide plus a couple of dishes. I am guessing that the Procom dishes for 47 and 76 are basically the same, with different flanges and feeds- we'll see.
Dan VK2GG (Millimeter man)

[VK2GG]

With regard to mounting the sub-harmonic mixer diodes,
thanks Peter for your info on Silver Epoxy. I have ordered some in a two pack configuration from a seller on EBay.
I further read a full description in the 47Ghz transverter kit manual: Under a microscope, place a drop of Silver Epoxy on one side of the pcb track. then with a wet tooth pick, pick up the diode and carefully place on the pcb into the drop of Epoxy. Then place some Epoxy on the other side of the diode, on the other track. Then cure for 3 hours at 100 degrees C.
I am unsure whether I have ordered the correct diodes - Philipp has both single diodes and back-to-back diodes. I have ordered two of the single diodes, plus the higher powered one to use as a beacon.
Maybe I should have ordered the MA4E1318 (double) instead of two MA4E1317 (single)??
Dan

[VK5ZD]

Hi

The mounting technique you describe is for the HSCH-9251 beam lead diode.
The diodes you've ordered (MA4E1317) don't have any 'leads' (if you can call 0.19mm of wire a lead ).
The MA4E1317 is just a die with two connection pads 0.4mm apart.

May your hands be steady, your magnification great and your lights be bright. Good luck!

73
Iain

[VK2GG]

Thanks Iain
I'll be looking for a Uni Physics department which has microwave friendly technicians!
BTW my Procom dish arrived today, and yes, it is the same dish as the Procom 47ghz one, just different waveguide sized hole in the flange,
easy to duplicate the feeds,
cheers,
Dan

[VK2XSO]

Hmmm.. I might have to take the 50GHz sweep generator to Wyong.

[VK2GG]

That would be handy Trash......
I now have a microscope and can see the little diode blighter. Haven't had much luck manouvering the little thing with tweezers - gets caught on rough bits on the track and skips away - just like SMD's do.
Need practice.
Dan

[VK2GG]

Matt,
I found I did have some reverse-action tweezers. I "weakened" them in a vise so as not to damage the little chip diode. Then I gave them a bit of a touch up with a file. They work brilliantly to pick up little chip cappies, etc.
I even had a practice placing the diode on to the tracks on the pcb held on the top of the microscope platten and back into the container again- no dropping!
I have decided that I will apply a drop of silver epoxy to the spot, then place the diode in situ using a head magnifier, then check with the microscope viewer and nudge the diode if necessary; I will then apply another small dollop of glue to each end of the diode. Sound like a good plan?
Dan

[VK2GG]

More news on the microscope front - Peter YGM has acquired a lower power scope which should be ideal - plus it's image is NOT upside down. He just needs to fashion a solid plate - that part was missing!
Pete has also made a couple of Procom dish feeds for 76ghz. Same method will be utilised on 122 and 241ghz - just need the WG7 and 5 and flanges.
We are nearing the fun stage! (I will tell you whenit starts)
Dan

[VK2GG]

Latest News!
The little diodes have been glued on!
Now to test if a DB6NT/DL2AM system will rival a VK3XPD system and actually work!
Dan GG