Question about double balanced mixer

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aldo
Posts: 8
Joined: Tue May 16, 2017 8:43 am

Question about double balanced mixer

Post by aldo » Thu Nov 02, 2017 12:00 pm

im newbee and i have a question about a double balanced mixer i see on the net this mixer :

LO,RF 8-12GHz
LO+10dBm
IF 0.03-4GHz
Double Balanced mixer

this mean that LO support 8-12ghz oscilator
RF : 8-12 ghz
IF : 0.03-4ghz

exemple if we have a QPSK modulator give RF out on 955mhz we must conect this OUT to RF or IF ? the goal is to reach the 3 cm band so this mixer is good or not i have some problem to understand IF and RF
the LO im using adf 5355 board .

pls who can put a small tutorial to make me understand how mixers work .

g0mjw
Posts: 907
Joined: Sat Sep 20, 2014 9:15 am

Re: Question about double balanced mixer

Post by g0mjw » Thu Nov 02, 2017 12:27 pm

Aldo,

Normally if you are mixing up you feed the modulated input signal into the IF port, the LO into the LO port and get the output from the RF port.

So in your case, you put your 995MHz into the IF - this is OK as it allows 30MHz to 4GHz. You put your 9.4 GHz LO into the LO port at 10dBm and you should find you get out signals at the sum and difference frequencies. You need to use a filter to select the 10 GHz signal you want.

IF power should not be more than about 0 dBm. Conversion loss will be about 7 dB so you will get about -7dBm out.

Mike

G4GUO
Posts: 626
Joined: Tue Feb 16, 2010 12:51 pm

Re: Question about double balanced mixer

Post by G4GUO » Thu Nov 02, 2017 4:32 pm

The other problem you will find is that the output of a Chinese ADF5355 board is only about -8dBm from the doubler port.
That is not enough to drive the LO of the mixer you have, it will cause poorer IMD performance and a far higher conversion loss
and may not work at all.

- Charles

aldo
Posts: 8
Joined: Tue May 16, 2017 8:43 am

Re: Question about double balanced mixer

Post by aldo » Thu Nov 02, 2017 10:39 pm

G4GUO wrote:The other problem you will find is that the output of a Chinese ADF5355 board is only about -8dBm from the doubler port.
That is not enough to drive the LO of the mixer you have, it will cause poorer IMD performance and a far higher conversion loss
and may not work at all.

- Charles

thanks exactly i buy a chineese board from alibaba arround 70 usd , and its not working at all so any idea or shematics for a working oscilator with pll please or other devlopment board who can work well for me

thx

aldo
Posts: 8
Joined: Tue May 16, 2017 8:43 am

Re: Question about double balanced mixer

Post by aldo » Sun Nov 05, 2017 9:08 pm

Hello who can help to make a 10 ghz Tx ? my QPSK modulator deliver 955mhz-1240mhz i want to convert and go to 10ghz but i dont find the good way to start my project , any help pls ?

g8gtz
Posts: 1162
Joined: Wed Apr 07, 2010 6:26 pm

Re: Question about double balanced mixer

Post by g8gtz » Mon Nov 06, 2017 4:13 pm

Hi Aldo

There are 2 ways you can get on to 10GHz from 900MHz - the first is the "build it yourself" approach exactly as you described in your previous posts and the ADF43xx is the best oscillator solution but you will need amplification on the LO and the final signal.

The other way is to buy a unit (new or secondhand) from DB6NT or other manufacturers. There was a talk on 10GHz at the BATC CAT17 - you can watch it here: https://www.youtube.com/watch?v=L-6bKaFhkEY

73 Noel - G8GTZ

G4GUO
Posts: 626
Joined: Tue Feb 16, 2010 12:51 pm

Re: Question about double balanced mixer

Post by G4GUO » Mon Nov 06, 2017 5:43 pm

As far as amplifiers are concerned I looked at using
https://www.minicircuits.com/WebStore/d ... VA-183A%2B
The devices are relatively cheap but when I got a quote from China to get a batch of
boards made using the correct Rogers material they wanted a lot of money $400 mainly
because the quantity 10 was so small.

It was suggested I get some boards made using thin FR4 as the tracks would be so short.
I didn't pursue that though.

I have some sample AVA-183A ics but without suitable boards they are not much use.

- Charles

aldo
Posts: 8
Joined: Tue May 16, 2017 8:43 am

Re: Question about double balanced mixer

Post by aldo » Mon Nov 06, 2017 8:00 pm

g8gtz wrote:Hi Aldo

There are 2 ways you can get on to 10GHz from 900MHz - the first is the "build it yourself" approach exactly as you described in your previous posts and the ADF43xx is the best oscillator solution but you will need amplification on the LO and the final signal.

The other way is to buy a unit (new or secondhand) from DB6NT or other manufacturers. There was a talk on 10GHz at the BATC CAT17 - you can watch it here: https://www.youtube.com/watch?v=L-6bKaFhkEY

73 Noel - G8GTZ
Hello do u think about this ? if yes wich amplifier must use please

question : LO and mixers for analog and digital are same ? !!
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