On 06/06/2015 01:28 PM, Ashhar Farhan wrote:
allison,
which transformer should take the trimpot? the LO transformer?
- f
On Sat, Jun 6, 2015 at 10:11 PM, allison <ajp166@xxxxxxxxxxx
<mailto:ajp166@xxxxxxxxxxx>> wrote:
The mixer as shown will has a higher conversion loss as most diode
mixers. Its difference is
lack of tapped coils that are also loaded by the resistors. That
loading may improve port
matching, however, the price paid in resistive losses to LO power
are about 6db.
I've never seen that commercially used.
I'd go trifilar as well. HINT: if the center tap of one of the
trifilar windings is interrupted by
a 100ohm pot with the wiper to ground you can achieve a greater
degree of balance
with typical results in the 50db or greater range. Tentec uses
this in some of their radios.
Especially handy for balance modulator where any improvement of
carrier to sidebands
is an advantage.
Allison
On 06/06/2015 12:26 PM, beninturkye@xxxxxxxxx
<mailto:beninturkye@xxxxxxxxx> wrote:
Hi Joe,
The resistors are 47 Ohm so you run up considerale losses, apart
from that, the resistors must be non inductance types and really
equal to eachother as the balance depend on that.
I really would take trifilar.
Typed on my Asus Zenfone 5.
Regards Ben PA9B.
ASUS'umdan gönderildi.
-------- Origineel bericht --------
Van:Joe Rocci
Verzonden:Sat, 06 Jun 2015 18:32:26 +0300
Aan:minima@xxxxxxxxxxxxx <mailto:Aan:minima@xxxxxxxxxxxxx>
Onderwerp:[minima] Re: Modified Diode Mixer
Ben
If the resistor values are large enough, you could minimize
additional conversion loss at the expense of more LO voltage. One
might also use RF chokes. All that said, I agree that trifilar
windings would be better.
Joe
W3JDR
Sent from my Galaxy Tab4 10.1 4G LTE Tablet
-------- Original message --------
From: beninturkye@xxxxxxxxx <mailto:beninturkye@xxxxxxxxx>
Date: 06/06/2015 10:29 AM (GMT-05:00)
To: minima@xxxxxxxxxxxxx <mailto:minima@xxxxxxxxxxxxx>
Subject: [minima] Re: Modified Diode Mixer
Dear mike,
In this mixer you have resistors loading the input and output so
you must expext some more signal loss than the usual 6 dB, so
think of 9 dB.
I would opt for trifilair windings.
Regards Ben PA9B
-------- Origineel bericht --------
Van:M
Verzonden:Sat, 06 Jun 2015 14:36:06 +0300
Aan:minima@xxxxxxxxxxxxx <mailto:Aan:minima@xxxxxxxxxxxxx>
Onderwerp:[minima] Modified Diode Mixer
Hi all,
I came across a modified diode mixer in an old Technical Topics in
Radcom (May 05), designed by G3UUR. It looks easier to build than the
mixer in the Minima 3 schematic, since it uses bifilar rather than
trifilar windings. I haven't built it, but would be interested to
hear if it has any disadvantages. I've attached it, and put it on my
site, psk-31.com <http://psk-31.com>
Mike G1ZVN
