[minima] Re: A (temporary) solution to my mixer problems
- From: Joe Rocci <joe@xxxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Wed, 22 Oct 2014 06:23:54 -0400
Both the KISS and the diode DBM operate using the switching principle. The
FET-based switching mixers MIGHT be less sensitive to reactive load swings, but
I've not seen any work that proves this quantitatively.
I think the move to a packaged mixer is good idea. In this rig, a known good
mixer is the lynch-pin of performance, so getting that variable out of the mix
is essential to getting a design nailed down. BTW, this ebay seller has had
Minicircuits JMS-1 level 7 mixers listed at $15 for 10 pcs for months:
http://www.ebay.com/itm/10-pcs-JMS-1-MINI-CIRCUITS-FREQUENCY-MIXER-2-500MHz-SMD-FREE-SHIPPING-/121157563325?pt=LH_DefaultDomain_0&hash=item1c358db3bd
This part is very similar to the ADE-1. At $1.50 ea, it's hard to pass up. I
purchased a set a few months back and they work well.
Joe
Sent from my tablet
-------- Original message --------
From Steve VK2SJA <vk2sja@xxxxxxxxxxx>
Date: 10/22/2014 12:55 AM (GMT-05:00)
To minima@xxxxxxxxxxxxx
Subject [minima] Re: A (temporary) solution to my mixer problems
But that's not a switching mixer. So my limited understanding is that now
you would need to add a diplexer and buffer amp between mixer and crystal
filter.
Over to Farhan on this one.
> Gang,
>
> After looking at the RF386 this afternoon I came to the conclusion that my
> only problem was my Minima. With -30 dBm on the output my signal was just
> too low, even for the RF386.
>
> I looked into the recent discussions about mixers and wanted to build one
> of them but I do not have the IC you discussed and I could not find a
> clear
> call on which one of the JFET mixers was the best.
>
> So I took a step back and realized that (to me) this project is more about
> building a working radio than running lots of mixers experiment. I
> completely removed the KISS mixer from my Minima and replaced it with one
> of the ADE-1 mixer that I had ordered a few months ago.
>
> My output is now at -15dBm @14.250 and -26@34.25.
>
> [image: Inline image 1]
>
> I should now have plenty enough power to drive the RF386!
>
> I think we should recommend this solution to new builders who are just
> getting started, at least until we have a good mixer that can easily and
> repeatability be built with good performance.
>
> I paid $15 for 4 of them on eBay. $3.5 a piece.
>
> Thoughts?
>
> 73,
> thomas
>
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