GB3GQ Update, 3.408Ghz Mixing & Filters

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G8DKC
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GB3GQ Update, 3.408Ghz Mixing & Filters

Post by G8DKC » Sat Mar 31, 2018 12:01 pm

Many have gone before, but...

DTX-1 at 1.3Ghz mixing with ADF4351 at 2.108GHz, filters and mixer...

Amazed how well 3.408Ghz working across workshop, very low signal from horn across to Titanium C1W-PLL Lnb, still playing with levels and filters...

RPi animated test card very useful, https://wiki.batc.org.uk/RPi_Test_Card :)

Peter

G4WIM
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Location: Freckleton, Lancs

Re: GB3GQ Update, 3.408Ghz Mixing & Filters

Post by G4WIM » Sun Apr 08, 2018 8:48 pm

Sounds like what I did for taking GB3FT at 1.315GHz up to 3.406GHz for GB3FB - check out the latest BATC mag for the post mixer filter.

I have some firmware I wrote for an Atmega328 to control the PLL, PA cooling fans and other stuff if it's any use to you.

G8DKC
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Re: GB3GQ Update, 3.408Ghz Mixing & Filters

Post by G8DKC » Mon Apr 09, 2018 8:39 am

Hi Tim,

Yes I saw your line up and go back to your article, no good re-inventing the wheel :)

Was very lucky with a rare 3.4Ghz filter on EBay ~ 250Mhz band pass, but like your filter build.

Building in electrical equipment box, old Dell 12v 60A psu case and fan with speed control, pulling air from top of cabinet.

Pic attached...

Thanks for the firmware control offer, will see how my effort works out.

Pics to follow as I progress.

Peter
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G4WIM
Posts: 115
Joined: Thu Jan 29, 2015 8:36 pm
Location: Freckleton, Lancs

Re: GB3GQ Update, 3.408Ghz Mixing & Filters

Post by G4WIM » Mon Apr 09, 2018 9:37 am

Looks to be coming along nicely - suspect you have the same type of PSU which we use on FB / FT, sounds like a jet engine when its running so much so that Steve G3WGU built a sound box around it to keep it quiet as it resides in his attic !

Good find on the filter - be interested to hear more about that.

OK about the firmware, we also have DTMF control using another Atmega - one for encode and another for decode.
The control logic is yet another ATmega which controls which rx gets routed thru to the tx and finally there's a pi zero generating test card captions.

73 Tim

G8DKC
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Re: GB3GQ Update, 3.408Ghz Mixing & Filters

Post by G8DKC » Tue Apr 10, 2018 8:05 am

Re 3.4Ghz filter

RLC ELECTRONICS F-10842 9619 Marked 3.4Ghz Fc ~ 250Mhz Bandpass.

http://www.rlcelectronics.com/products/ ... lters.html

I did some "very rough" external measurements totally sealed, 5 rods by the look of it, and used calculator on...

https://www.changpuak.ch/electronics/co ... signer.php

In practice cleans up and good signal out.

Peter
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G8DKC
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Re: GB3GQ Update, 1.3Ghz IF

Post by G8DKC » Mon Apr 23, 2018 12:55 pm

DTX-1, 1.3Ghz driver and filter mounted on door.

Peter
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