On 06/06/2015 05:16 PM, Arv Evans wrote:
HelloYes, but across the winding loads the transformer, alters impedances
Might the resistors be replaced with a bifilar transformer connected as
center-tapped? Maybe the balancing pot could them be between these
two windings?
Arv K7HKL
_._
On Sat, Jun 6, 2015 at 2:20 PM, allison <ajp166@xxxxxxxxxxx
<mailto:ajp166@xxxxxxxxxxx>> wrote:
On 06/06/2015 01:28 PM, Ashhar Farhan wrote:
allison,
which transformer should take the trimpot? the LO transformer?
- f
I've done it on both but I find the one on the LO end, assuming the
center tap at the other end is the IF port.
Allison
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
