Working on 10GHz

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radiogareth
Posts: 723
Joined: Wed Jan 06, 2016 9:46 am

Working on 10GHz

Post by radiogareth » Tue Jun 08, 2021 7:24 pm

Having recently received a spare Bullseye LNB ($29.99 delivered from RTLSDR shop via AliExpresss) I set about giving it some gain for portable use. From my stock I extracted a BNIB BSB Mini-dish and had a look at the kit contents. The original LNB was not plastic encased like the modern variety so suits a 22mm round 'pipe'.
Removing the plastic case from the Bullseye (6 plastic clips that can be gently prised open) revealed just that, a round body of approximately 22mm diameter, with some of a box assembly for the electronics getting slightly in the way. By splitting the original BSB LNB boss in half and carefully grinding away plastic (glass filled nylon I think, good stuff) it was possible to mount the LNB as BSB intended.
Mounting the dish on a suitable cross-bar and tripod, I pointed it at the sun and experimented with the angle until the centre cap was illuminated by the suns image. So pretty much at the focal point then :-)
With RX sorted I moved to TX, hoping to use my Pluto's 5th harmonic and amplifying it a bit. I recalled I bought a "dish feed to WG16" from Bob Platts about 20 years ago, this fits directly into the LNB mount with a few turns of tape to give the holder some grip. Just got to build/convert an old Gunn diode 10GHz cavity to SMA feed and I'll be good to go.
Both dishes can be mounted as shown, or a bi-quad feed for 3.4 can quickly be substituted to the TX dish
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if I want to use 9cms.
All good stuff....
Gareth

g4eml
Posts: 417
Joined: Thu Apr 26, 2018 9:36 am

Re: Working on 10GHz

Post by g4eml » Tue Jun 08, 2021 10:42 pm

Hi Gareth,

Looks good.

Using the 5th harmonic of the Pluto is fine for local testing but it needs a very large amount of gain to get to usable levels. 30dB will give you about 1mW which would be enough for line of sight paths.

Colin.

g4eml
Posts: 417
Joined: Thu Apr 26, 2018 9:36 am

Re: Working on 10GHz

Post by g4eml » Wed Jun 09, 2021 10:04 am

You may be able to make use of the original BSB LNBs by cutting the amplifiers from the boards. I made a good preamp by doing something similar.

The SU-02 ‘Franco’ boards are also a good source of amplifiers. Franco is still selling them at rf-microwave.com but his minimum order amount and high delivery charge makes them awkward to get in the U.K. I wonder if anyone has any sitting unused in a drawer?

The only easy to use and easy to obtain MMIC device with gain at 10GHz is the NLB310 but you will only get about 8dB per device. Mouser sell them.

Colin.

G4HTZ
Posts: 184
Joined: Sat Aug 02, 2014 4:21 pm

Re: Working on 10GHz

Post by G4HTZ » Wed Jun 09, 2021 10:56 am

g4eml wrote:
Wed Jun 09, 2021 10:04 am
You may be able to make use of the original BSB LNBs by cutting the amplifiers from the boards. I made a good preamp by doing something similar.

The SU-02 ‘Franco’ boards are also a good source of amplifiers. Franco is still selling them at rf-microwave.com but his minimum order amount and high delivery charge makes them awkward to get in the U.K. I wonder if anyone has any sitting unused in a drawer?

The only easy to use and easy to obtain MMIC device with gain at 10GHz is the NLB310 but you will only get about 8dB per device. Mouser sell them.

Colin.
Colin
I have a few of the Franco boards …never used …as supplied from Franco when I bought a few to make an order up .
£6 a board posted if anyone interested
If not can stay in the draw :D
Steve G4HTZ
Great Wakering Essex JO01JN

g4eml
Posts: 417
Joined: Thu Apr 26, 2018 9:36 am

Re: Working on 10GHz

Post by g4eml » Wed Jun 09, 2021 4:30 pm

Hi Steve,

Thanks for the offer. I don’t need any myself at the moment but they might be useful for Gareth.

Colin.

radiogareth
Posts: 723
Joined: Wed Jan 06, 2016 9:46 am

Re: Working on 10GHz

Post by radiogareth » Wed Jun 09, 2021 7:44 pm

Yes please Steve, a couple of Franco boards would be a great start. Send me a PM with payment details (PayPal or bank transfer) and I'll get onto it.
Thanks
Gareth

radiogareth
Posts: 723
Joined: Wed Jan 06, 2016 9:46 am

Re: Working on 10GHz

Post by radiogareth » Wed Jun 09, 2021 7:48 pm

g4eml wrote:
Wed Jun 09, 2021 10:04 am
You may be able to make use of the original BSB LNBs by cutting the amplifiers from the boards. I made a good preamp by doing something similar.

The SU-02 ‘Franco’ boards are also a good source of amplifiers. Franco is still selling them at rf-microwave.com but his minimum order amount and high delivery charge makes them awkward to get in the U.K. I wonder if anyone has any sitting unused in a drawer?

The only easy to use and easy to obtain MMIC device with gain at 10GHz is the NLB310 but you will only get about 8dB per device. Mouser sell them.

Colin.
Good idea Colin, I have 4 of them to experiment with! RX side is fine, but at these signal levels I assume even 'RX' parts can be pressed into service in the early TX chain.
Gareth

radiogareth
Posts: 723
Joined: Wed Jan 06, 2016 9:46 am

Re: Working on 10GHz

Post by radiogareth » Wed Jun 09, 2021 7:53 pm

SMA to WG16 transition made and set up, such as I can. MER 17 at 40m down the garden.....
Its a start ;-)
Gareth
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g4eml
Posts: 417
Joined: Thu Apr 26, 2018 9:36 am

Re: Working on 10GHz

Post by g4eml » Wed Jun 09, 2021 10:54 pm

Gain is gain. You will probably find the receive amplifiers will give a few milliwatts on transmit when saturated.
You will probably need a negative bias supply. Have a look at the data for the Franco boards for some ideas.

Colin.

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