The NE602 and NE612 are mixers with two pins for the internal Xtal oscillator.
And here there is an output pin and an input pin, and you can get some signal
from the output pin and give it to the input pin of the next mixer.
Groetjes Ben (in Turkije)
-------- Origineel bericht --------
Van:Joe Rocci <joe@xxxxxxxxxx>
Verzonden:Thu, 02 Jun 2016 13:50:48 +0300
Aan:minima@xxxxxxxxxxxxx
Onderwerp:[minima] Re: looking for HF1
What’s the NE602 for?
From: Ben Aupperlee
Sent: Thursday, June 02, 2016 6:40 AM
To: minima@xxxxxxxxxxxxx
Subject: [minima] Re: looking for HF1
Hello Joe,
YES, that is good news, and i think if you place 3 of those, they can do with
one Xtal, just you can use a NE602 with an external frequency source.
YES, again, here in T-land there is not a single part-shop, i have to go to
Germany by bus and import one box of components at a time. I can have
Conrad.com send me a few packages a year, but they do not have the right stuf
like these chips. What they do have are bfr93 transistors for 0,22 E and an
Arduino expander chip giving 8 more input/output pins.
I found an old module for TXBF TransmitterBandFilter
And i am translating the Dutch text. The bad news is it uses prefab inductors,
the good news is that you do not have to wind a single coil .
It works, as it was part of a project of wich 150 were build.
Regards Ben. PA9B (in Turkije)
-------- Origineel bericht --------
Van:Joe Rocci
Verzonden:Thu, 02 Jun 2016 13:22:40 +0300
Aan:minima@xxxxxxxxxxxxx
Onderwerp:[minima] Re: looking for HF1
Clippers, limiters or buffers won't cure spurious developed inside the chip.
Further, all of these circuits are highly non-linear so if another signal
leaks into it, intermodulation products will develop.
BTW, here in the US, Si570 is roughly $11 and Si5351 is a little over $1.
However, Si5351 requires a crystal and a couple caps. Cheap enough to use 3 of
them.
One other point Ben. The 1st IF doesn't have to be precisely 45 mhz, so you
can design around commonly available crystals. Since you're already designing
with parts that aren't commonly available at your corner hobby shop and will
require a mail order , let me suggest that fundamental mode crystals are
available to over 200 mhz and are very inexpensive.
Sent from my Verizon Wireless 4G LTE Tablet
-------- Original message --------
From: Ben Aupperlee <beninturkye@xxxxxxxxx>
Date: 06/02/2016 3:45 AM (GMT-05:00)
To: minima@xxxxxxxxxxxxx
Subject: [minima] Re: looking for HF1
Hello again, and again,
Can we run the oscillators at double the frequency and devide the output by
two, that gives the output block wave with hard hilevel and lowlevel, and a
reasonable duty cycle of 50%. That should do away with crosstalk.
Or just use two clipping amplifiers to get hard hi and low levels.
Regards Ben (in Turkije)
-------- Origineel bericht --------
Van:Ashhar Farhan
Verzonden:Thu, 02 Jun 2016 10:13:47 +0300
Aan:minima@xxxxxxxxxxxxx
Onderwerp:[minima] Re: looking for HF1
the 32 mhz is too close to the 30 mhz LPF filter's cut-off. the can
oscillators are quite noisy too. i think we can expend a few transistors and
keep it simple : use the Si5351 (if you want) or the Si570 (if you insist).
either way, the rest of the circuit will remain the same.
- f
On Thu, Jun 2, 2016 at 12:40 PM, Ben Aupperlee <beninturkye@xxxxxxxxx> wrote:
Hello everybody,
To solve this problem, I am thinking of my old HW101 from Heathkit, there we
had as input filter a tuned preselector, consisting of two tuned coils and a
tube inbetween, that was a good way of making life easy for the first mixer, a
homebrew diode ring. This preselector was used during transmitting as the
bandfilter to get rid of the unwanted sideband. I think if anything else fails
we could think of a modern version of this preselector, unfortunately, it
means a second (analog) tuning knop on the front panel. (Unless we can
figure-out a way to let the processor do this extra tuning).....
As i think of this, i do have an old module from an earlier trx using
pindiodes to switch-in 7 bandpass filters, this might do, if i change the 6
meterband into 60. I still have the schematic somewhere . (4 and 10 MHz away
is far enough for even the sloppiest filter)
Another way is using one fixed oscillator block and two si570's or do some
more calculations and measurings and come-up with a number of low and hi-pass
filters.
My bet is for now on the si5351 using 2 out of 3, with an SMD oscillator block
of 32 MHz, using 42 MHz as first IF. And the tx bandfilter.
Regards Ben PA9B (in Turkije)
-------- Origineel bericht --------
Van:Ashhar Farhan
Verzonden:Thu, 02 Jun 2016 08:55:03 +0300
mailto:Aan%3Aminima@xxxxxxxxxxxxx
Onderwerp:[minima] Re: looking for HF1
The ideal case, of course, is that we use the Si5351 for all the three
oscillators. let me take one at a time
1. 1st oscillator : this is essential as the 1st oscillator needs to be
tunable. There is a subtle catch : if there is a leakage of the any other
oscillator into this, the output will certainly show up in the transmitted
signal. we can live with a bad receiver, we will be arrested for a bad
transmitter. so, this is legal stuff.
2. 2nd oscillator : I chose 45 MHz IF frequency as it is easily handled by
conventional HF methods and it is sufficiently above the HF range to be
cut-off with the usual LPF filtering. The oscillator needs to be around 55
MHz. The trouble is that overtone oscillators are very particular about being
tuned. i am looking at ways of avoiding critical tuning. but one main reason
that we should look at using Si5351 for this application is that the overtone
oscillator will be a no-brainer.
3. BFO : the bfo needs to be tunable over a small range to allow for the upper
and lower sideband selection. at present we are using a VCXO to do this.
having Si5351 do this will make things really simple.
now, here is the catch, BFO, if it leaks into the VFO (1st oscillator) will
show up as a strong carrier in the transmit output as it is inside the
front-end LPF's passband. The 55 MHz oscillator, when leaked into the VFO will
beat with the oscillator and produce a response that is consistenly 10 MHz
away from the signal. In fact, I faced this in the PCB that I designed for the
HF1. It works like this : let's assume that we are tuned to 14 MHz, our VFO
would be at 45+14 = 59 MHz. This 59 MHz will beat with the leaked 55 Mhz and
produce a transmission spur at 59-55 = 4 MHz.
So, that is the whole problem set. over to you guys now...
- f
On Thu, Jun 2, 2016 at 10:48 AM, Ben Aupperlee <beninturkye@xxxxxxxxx> wrote:
Hello Joe (and the whole bunch),
We can go for 2 out of 3, with possebly buffering or so, as there are little
SMD blocks containing Xtal and oscillator chip, virtually a one component Xtal
oscillator that can be useful for osc nr 2. Conrad.com sels them for 1 to 3
Euro, single item price. They only do not have the exact frequencies of 55 or
35 MHz, but I hope there are outlets that are better sorted.
But whatever we do here, it will not interfere with the construction and
layout of the motherboard , so that can go on. As long as we agree on the
interface with the motherboard, and stick to that.
I see this oscillator sub-board as a rectangular board, standing on one of the
long sides, not higher than 2 or 3 cm so it fits inside a shielding box, with
some pins in the motherboard, 3 pins for signal and close by 3 ground pins,
then somewhere on one end of the board power supply pins. The clock and data
lines comes directly from the digital board, mounted on the front panel and
housing the processor and LCD. And should be shielded from the analog part of
the set as this whole digital circuit radiates the 16 MHz clock frequency.
That is the reason I like to split the whole set in an analog and digital
part. (With a solid shield inbetween)
Somebody might contact the si manufacturer and ask if they have an application
note for this chip, exp
