Power on 2M

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G3VZV
Posts: 21
Joined: Mon Feb 25, 2008 12:38 am

Re: Power on 2M

Post by G3VZV » Sat May 18, 2019 8:23 am

Hi Gareth,

The best filtered pre-amp for 2 metres is this one from David G0MRF https://shop.amsat-uk.org/G0MRF_2m_Filt ... 28541.aspx

It was originally designed for an early SDR dongle that suffered badly from out of band overload.

detailed notes are here https://ukamsat.files.wordpress.com/201 ... _notes.pdf

It might not have the 55dB gain that Noel was talking about but it will be amplifying only the signals that you want!

good luck

Graham G3VZV

g8gtz
Posts: 1137
Joined: Wed Apr 07, 2010 6:26 pm

Re: Power on 2M

Post by g8gtz » Sat May 18, 2019 8:33 am

Looks interesting Graham

And I wasn't implying you need 55dB of gain but you do need something...

73
Noel

radiogareth
Posts: 304
Joined: Wed Jan 06, 2016 9:46 am

Re: Power on 2M

Post by radiogareth » Sat May 18, 2019 8:46 am

Thanks, one of the Amsat units ordered :-)
On a related note, using other software for RX it crossed my mind that as SDRAngel does DVBS (video here https://www.youtube.com/watch?v=Bb8S_J9 ... Eu&index=2) and that my Pluto does 70MHz upwards I thought I'd give it a try.
Undoubtedly powerful but the GUI is very tricky for me, I could not get copy across the shack although the Pluto is clearly picking up something. I've had a quick download of Marks software but I can't select a device. So much to try, but good fun trying...

Gareth

G4FRE
Posts: 86
Joined: Fri May 26, 2017 6:57 am

Re: Power on 2M

Post by G4FRE » Sat May 18, 2019 9:33 pm

I have used the g3sek 144MHz dg8 preamplifier in front of my tuner on 2m to successfully receive Noel and Mike. I also have a dg8 modified for 6m with 2 outputs and a dg8 modified for 4m with 2 outputs, both of which work well rejecting out of band signals
Dave
G4fre
Last edited by G4FRE on Mon May 20, 2019 2:42 pm, edited 1 time in total.

radiogareth
Posts: 304
Joined: Wed Jan 06, 2016 9:46 am

Re: Power on 2M

Post by radiogareth » Sun May 19, 2019 4:16 pm

Well success at last, out first 2-Way DATV contact on 2M, in fact our first DATV contact. I put up my portable 12 element ZL and tried adding a cavity filter then +18db of gain but MiniTiouner just couln't get a picture. Plugged into the Portsdown RTL with preamp and NO filter, +13dB signals at 125 SR. I could receive Martin at 250sr and occasionally at 333sr, he has a bit more erp than me.
Dongles not that bad at all after all.
Onward to boxing and switching and making things a bit safer!!

Thanks to the people who work to make this possible with hardware and software :-)

Gareth

M0YDH
Posts: 155
Joined: Sat Dec 31, 2016 5:59 pm

Re: Power on 2M

Post by M0YDH » Tue May 21, 2019 8:00 pm

Hello Noel
The DG8 pre-amp is available as a short kit from SDR-Kits
https://www.sdr-kits.net/DG8-Pre-Amp-2M-Short-Kit

Any Mini-Circuits parts may require an EZ Samples application on their website to get them. FOC. It's been a while since I read the DG8 manual and I can't remember what's in it.

Regards
David M0YDH

G4FRE
Posts: 86
Joined: Fri May 26, 2017 6:57 am

Re: Power on 2M

Post by G4FRE » Wed May 22, 2019 7:49 am

All the other parts needed for the preamp are available from Farnell. The sdr-kits page refers you to the construction guide which in turn refers you to Ian's web site article at http://www.ifwtech.co.uk/g3sek/vhfdx/dg ... p-v7-4.pdf

Dave
G4fre

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