Hello
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> 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> 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 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
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
Date: 06/06/2015 10:29 AM (GMT-05:00)
To: 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
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
Mike G1ZVN
