Hello Dan ,
could you pleas check the link ?
I was not able to find the page .
73-Claudio
-----Messaggio originale-----
Da: [email protected] [mailto:[EMAIL PROTECTED] Per conto
di Daniel Jackson
Inviato: domenica 6 agosto 2006 16.14
A: [email protected]
Oggetto: [Spam] [soft_radio] Re: Huff & Puff News!
Claudio I1RFQ And Others Hello!
{A 455kHz and 10.7Mhz Huff and Puff VFO Stabilizer Scheme: ka9rza}
This is a better stabilizing and i.f. mixing scheme which I have
currently been working here. I think this one will be used allot and I
leave it up to you to make your stabilizer circuit better with time.
Updated file:
http://f1.grp.
<http://f1.grp.yahoofs.com/v1/4PXVRJwnBiyB8gXRzZS5g9RWbo5NCT1jPeZ6f0vsVrj2Nn
LvWYASyQv2vjX_iZR6Ex-pMU5zcyAX_oMY7h2N8B-ZqNnimPGuUzUTE-Y/Push%20Pull%20VFO%
20Sychronizer.zip>
yahoofs.com/v1/4PXVRJwnBiyB8gXRzZS5g9RWbo5NCT1jPeZ6f0vsVrj2NnLvWYASyQv2vjX_i
ZR6Ex-pMU5zcyAX_oMY7h2N8B-ZqNnimPGuUzUTE-Y/Push%20Pull%20VFO%20Sychronizer.z
ip
In the past 24 and 48 hours I have made the circuit operate even
more ideal. So I am moving onto Mosfet and IC quadrature detector
ideas and I will use the H&P model here to tune those detectors with.
The better scheme today (with the current H&P "Push Pull VFO
Synchroizer.zip" test model) for better purposes is as follows:
I have converted the H&P's VFO tuned circuits down frequency to tune
around the RF region of 455 kHz to 1455 kHz and then mix that with a
very common CB radio 10.240 MHz PLL crystal to tune around in the 10.7
MHz receiver i.f. regions, with around 1 MHz bandspread tuning there
about: to 11.695 Mhz. So far it is running very well over here at 455
kHz under digital/crystal control.
10.240 MHz + 0.455 MHz = 10.695 MHz
10.240 MHz crystals are common in crystal grab bags specials and can
be ordered in bulk from allot of places. And they are likewise cheap
since there is massive use and manufacturing of these 10.240 MHz
crystals. Also, the main tuning capacitor can be the common high
quality medium wave broadcast variables of the 1/4" tuning shaft
types. Or good quality transmitter tuning types in the regions of
approximately 360pF to 580pF per ganged section.
Now 455 kHz is somewhat more stable in itself in a VFO making drift
smaller. VFO stablilty tends to increase with lowering the frequency
and near the VLF regions it can be fairly good. Here the H&P
frequency locks appear closer together and the inbetween regions are
better controlled in terms of random hertz wise drift. The random
motioned is slower here, and so the digital control is better for
those frequencies that are not in true lock regions. {It satisfies me
now that I have a useful and stable scheme worked out for others to use.}
Adding a little digital control to 455 kHz up to 1455 kHz then is
the way to go with this circuit (that is not based upon a 38 kHz watch
crystal such as the more current H&P designs are doing). And again
the 10.240 Mhz crystals are very common to obtain. Likewise the 10.7
MHz i.f. is very common also, and so; I will make a quadrature
detector this way, where the detector operates around the 10.7 MHz
i.f. of allot of receivers. It should tune around up and down the
region fairly good in very fine hertz terms over 1 Mhz. With
selectable rate and period adjustments. And its strength is that it
works in a common i.f. scheme of frequencies.
So I want to tune the VFO from 455 kHz to 1455 kHz. Resulting in
tuning in the 10.7 MHZ i.f. region after mixing with 10.240 MHz:
from: 10.240 MHz + 0.455 MHz = 10.695 MHz
to: 10.240 MHz + 1.455 MHz = 11.695 MHz
The economy of the idea is in the details of the mixing frequencies
in that they can also result in mixing a 455 KHz i.f. up to the 10.7
Mhz i.f. and tuned then with the mixed VFO in that region of a single
10.7 Mhz region quadrature detector. So one model can both tune 10.7
MHz and 455 kHz i.f. receivers.
And lastly the 10.240 MHz crystal LO IN to the VFO/10.7 MHz mixer
will be slightly adjustable +/- about 3 Khz to make good use of all of
the hard frequency lock ups the VFO now has through applied digital
control. Hence making possible fine tuning resolution in all
frequency positions.
This gives us two options of use; and then, there is also the third
option of custom building a receiver front end of your own to mix the
bands you want to 10.7 Mhz for tuning and detection.
The file on the "Push Pull VFO Synchroizer.zip" has had the
transistor Q1 updated to a more rugged 2N3734 (NTE324) with changes
also in the supporting resistors to make the circuit stay in there
without becoming faulty. And so I found out I had to change that via
the hard way. Likewise I have introduced some decoupling capacitors
in the new resistor made filtering scheme to make simple RC types of
filters to attenuate ringing and other undesirable mixing products and
RF feedback paths between the chips.
This should then be enough information for anyone to begin to make
good use of. I have given out allot of views lately but this seems to
be the better use of them and so I will just let folk experiment and
make changes to suit there needs and when I have something more to
report on the circuit idea and its perfomances then I will but, for
now, this is sign off time on this topic.
Dan ka9rza
[Non-text portions of this message have been removed]
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