Re: Scatterpoint Activity column
Paul Randall G3NJV
Hi, I intend to mix down to 2m and bought a TOKO 5HW-73050A-735 filter off eBay for 3 quid to give the mixer a better chance.
What mixers are you guys planning to use?
Sent from my Samsung Galaxy smartphone.
-------- Original message --------
From: "John E. Beech" <john@...>
Date: 18/05/2020 22:26 (GMT+00:00)
Subject: Re: [UKMicrowaves] Scatterpoint Activity column
Tnx fer that Andy. In that case I might try a very simple Schottky diode mixer for starters. I've got a series of 3dB, 6 dB & 10 dB BNC attenuators I can clag in to see how much I need & then build a dedicated attenuator.
de John G8SEQ
> -------Original Message-------
> From: Andy G4JNT <andy.g4jnt@...>
> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
> Subject: Re: [UKMicrowaves] Scatterpoint Activity column
> Sent: May 18 '20 18:46
> The output of any LNB is so high you'll need attenuation rather than
> The broadband noise output over the complete IF band from 600MHz to
> 2GHz or so is so high, it can run into compression in some mixers.
> DBMs shpuld be OK, but the I/Q downconverter I used to get to 28MHz
> required at least 10dB attenuation of the 739MHz input to stay
> comfortably in the linear region.
> Don't forget image filtering if you use a simple mixer - otherwise you
> throw away 3dB S/N on every signal you hear
> On Mon, 18 May 2020 at 17:57, John E. Beech <john@...> wrote:
> > Hi John,
> > I don't know if this is of any interest, but while I have been
> > trying to revive my SSB electronics L 23 S TVTR, my brain went into
> > overdrive. Having recently bought a NanoVNA, I now have an easily
> > programmable LO with which to make a simpler SDR for QO-100. My LNB
> > puts out 739 MHz. By injecting 739 MHz into a suitable mixer ( ie a
> > copy of the Rx mixer in the L 23 S, I down convert the 739 MHz to
> > baseband to use with some existing software I have.
> > But there are more questions than answers. Will I need any
> > amplification/filtering at 739 MHz before the mixer or will it have
> > sufficient gain? Should I put an audio buffer amplifier between the
> > mixer and the sound card input. Has anyone already done this or am I
> > barking up the wrong tree?
> > de John G8SEQ
> >> -------Original Message-------
> >> From: John Worsnop <johnworsnop@...>
> >> To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
> >> Subject: [UKMicrowaves] Scatterpoint Activity column
> >> Sent: May 18 '20 17:45
> >> GE All,
> >> I've had no contributions for the Scatterpoint activity news this
> >> month so far, so it'll be "The G4BAO report" unless I get
> > something
> >> before lunchtime Wednesday.
> >> Doing anything interesting? made any out of the ordinary QSOs?
> >> switched the rig on instead of checking the web for activity? had
> > a
> >> QSO that didn't involve exchanging "59007 IO92WI" ?
> >> ;-)
> >> Send it to me at the above address before Wednesday Lunchtime and
> > the
> >> UKuG will put your name in lights............
> >> 73
> >> John