[Johnson] Ranger/Valiant with Xtals

[Sherrill Watkins]

Dear Fabio: After reading the excellent comments of Mr. Ed Worst, I looked at
the schematic of my Valiant. It has a 25 pf and a 200 pf capacitor and a
0.005 capacitor all connected in series. One end is connected across the
crystal and the other end is connected to ground. The crystal and these
series capacitors are also shunted by a 33K ohm resistor to ground across the
control grid of the 6CL6 crystal oscillator, V3, tube. I do not know what the
series capacitance of this is but I suspect it is very close to that of the
Ranger? I also suspect that the E.F.Johnson Company would have designed the
Ranger and Valiant to both transmit on the same frequency using the same
crystal. - 73- Sherrill W. k4own.   

-----Original Message-----
From: Ed Worst [mailto:edworst at att.net] 
Sent: Monday, December 06, 2004 3:18 PM
To: Fabio Liberatori; Johnson List
Subject: Re: [Johnson] Ranger/Valiant with Xtals


Hello Fabio,

When you ordered the crystals, did you specifically state that they were for
the Ranger (or Valiant)?  Most crystals from that era were made to work on
the frequency specified with a "correlation capacitance" of - in the case of
the Ranger - 23pf.  This is the total capacitance that appears in parallel
with the crystal to form a high  Q resonant circuit.  I picked the values of
the capacitors (24pf and 200pf) off my schematic for the Ranger.  I no longer
have a Valiant, so I can't tell if it's the same or not.  If the crystal
wasn't fabricated with that correlation capacity, it could be off frequency,
or not even oscillate at all in that circuit.  You might be able to return
the crystals since everything (housing, blank, cover, springs) is re-usable.

Does everything work OK on 20m when you're in the VFO position?

Will the crystals oscillate in the 40m position?

Hope this is of some help.

73,
ed - k9ew

----- Original Message -----
From: "Fabio Liberatori" <liber.fab at iol.it>
To: <johnson at mailman.qth.net>
Sent: Friday, December 03, 2004 14:23 PM
Subject: [Johnson] Ranger/Valiant with Xtals


>
>      Hello,
>               I recently bought two 7.143 MHz xtals for 14.286 MHz use 
> in my Johnson transmitters, but no luck... Both do not oscillate, even 
> if they are of new production (fitted into the old FT-243 case).
> I checked the correct position on the xtal socket, of course...
> I did any other attempt I was able to imagine...  Cleaning contacts,
> changing position, and so on...).
>
> Is my 7.143 xtal frequency choice  wrong for 20 meters use ? Do I need 
> actually 14.286 MHz xtals ?
>
> Does anybody use Rangers and Valiants with xtals here on this 
> reflector ?
>
>      Any suggestion will be very appreciated,
>
>                 Fabio, I0LBE
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