[Boatanchors] SP-600 J-11

[James A. (Andy) Moorer]

My SP-600 page has a Java calculator on it that computes the correct
(fundamental) frequency and the harmonic number:

http://www.jamminpower.com/main/sp600.html

Having tried it, I will say that the higher-frequency crystals don't work
terribly well - anything over fundamental mode doesn't generate a very
strong signal out of the oscillator and the audible result is decreased
sensitivity. As an engineer, I can tell you that it is quite hard to make
one oscillator circuit that handles the entire 1-30 MHz range with no
coil-switching or tuning, so it is not surprising that it works better on
some bands than others.

Note that even when using the crystals, you still have to "tune" the radio
to the desired frequency to align the 2 RF amplifier stages.

Enjoy!

James A. (Andy) Moorer
www.jamminpower.com

----- Original Message ----- 
From: "jmfranke" <jmfranke at cox.net>
To: <boatanchors at mailman.qth.net>; <af4k at hotmail.com>
Sent: Wednesday, March 10, 2010 3:38 PM
Subject: Re: [Boatanchors] SP-600 J-11


> From: http://www.radioblvd.com/sp600_rebuild.htm
>
> The Crystal Controlled Switchable Local Oscillator ("X" option)
>
> This unit allows the operator of an "X" optioned SP-600 receiver to
> substitute a crystal LO for the regular LO for increased stability. Six
> crystal sockets allowed the user to install HC-6 crystals for fixed
> frequency operation. A six position switch allowed selecting any of the
> crystals installed. A vernier frequency control was also provided. The
> crystal switch and the frequency vernier were brought out as two extra
> controls added to the upper right section of the front panel.
>
> When selecting a Crystal Controlled LO frequency, only the LO is changed -
> you will still manually have to tune the receiver to the selected
> operating
> frequency in order to have the RF and Mixer stages also tuned correctly.
> You'll need to install the correct frequency HC-6 crystal which is not the
> same frequency that you want to tune in. The manuals will provide the
> formula to calculate the crystal frequency required for the desired
> receive
> frequency. Basically, 455kc or 3.955mc is added to the desired receive
> frequency to obtain the correct crystal frequency depending on the band
> and
> whether the receiver is operating single or double conversion. Also, on
> the
> higher frequency bands the result is divided by 3 or 4 for operation on
> the
> crystal frequency harmonic.
>
> John  WA4WDL
>
> --------------------------------------------------
> From: "Radios R. Me" <radios_r_me at yahoo.com>
> Sent: Wednesday, March 10, 2010 3:14 PM
> To: <boatanchors at mailman.qth.net>
> Subject: Re: [Boatanchors] SP-600 J-11
>
>> Thanks Bob - do you know if these are fundamental crystals that just run
>> at, or close
>> to the desiredreceive frequency? If so, are the FT243 types (if you
>> happen
>> to know!)
>>
>>
>> I had a couple of people asking me for crystals for their SP600 radios,
>> so
>> they
>> must be the versions of the radio that have the sockets in them
>> already...
>>
>>
>> 73 - Brian "Bry" Carling, AF4K
>> = = =
>> Please use my main e-mail address:  af4k at hotmail.com
>>
>>
>>
>>
>> ________________________________
>> From: rbethman <rbethman at comcast.net>
>> To: Boatanchors Mail List <boatanchors at mailman.qth.net>
>> Cc: Radios R. Me <radios_r_me at yahoo.com>
>> Sent: Wed, March 10, 2010 12:01:50 PM
>> Subject: Re: [Boatanchors] SP-600 J-11
>>
>> Bry,
>>
>> The Northern SP-600 doesn't have the module that is in the JX-17 for
>> crystal placement and selection.
>>
>> That module came along quite a bit after the "early" variation.
>>
>> They allow for fixed frequency use, I think.  Not having had one of
>> those, I can't really say.
>>
>> The Northern Radio contract, NO bsr 57519, apparently was in the '50s.
>> It had as part of the "system", two of their SP-600s, a LMO, Local
>> Master Oscillator, and speaker all in a rack.
>>
>> The LMO would set the frequency for BOTH receivers.  There were two
>> antennae, one attached to each receiver.
>>
>> Well, I got a bit long.  However, I do not see immediately, a way to
>> add this crystal module, and certainly have never seen them separate.
>> I believe that they were factory installed.
>>
>> Bob - N0DGN
>>
>> On 3/10/2010 10:57 AM, Radios R. Me wrote:
>>>
>>>Hi
>>>Bob - do you know if there is some scheme for adding crystals in the
>>>SP600?
>>>>I have had a few folks asking me about this lately.
>>>
>>>>If so, would they be for fixed frequency operation? extra bands or what?
>>>
>>>
>>>>73 - Brian "Bry" Carling, AF4K
>>>
>>>= = =
>>>>Please use my main e-mail address: af4k at hotmail.com
>>
>>
>>
>>
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