[Collins] Split Mode

[Garey Barrell]

Yeah, but back then MANY SSB DXpeditions would transmit just below 
14.200, which was "out of band" for US  SSB Hams, and listen just above 
200.  So the split was only 5-10 kHz but just happened to be across the 
"Collins Line"!   There must have been at least "some" DXpeditions using 
other than Collins!!

I know I called more than a few locals on the telephone who were sending 
their call on SSB and covering up the CW DX at the bottom of the band!  
The usual response was "d'oh! that #%*^#& cable again"....  :-)

73, Garey - K4OAH
Atlanta



Dr.Gerald N. Johnson wrote:

>Back in the days when the S-line was king, the DXpedition would have been using one too and so would not have split outside a standard 200 KHz range. Most often only a 5 to 15 Khz split. Doing a 200 KHz plus split is making the DXpedition look like a band hog.
>
>73, Jerry, K0CQ, Technical Advisor to the CRA
>Dr. Gerald N. Johnson, Electrical Engineer
>
>
>  
>
>>------- Original Message -------
>>    
>>
>>From    : Garey Barrell[mailto:k4oah at mindspring.com]
>  
>
>>Sent    : 2/14/2006 10:57:44 AM
>>To      : collins at mailman.qth.net
>>Cc      : 
>>Subject : RE: Re: [Collins] Split Mode
>>
>>    
>>
> >
>Dr. Gerald N. Johnson wrote:
>
>  
>
>>On Tue, 2006-02-14 at 09:59 -0500, Garey Barrell wrote:
>> 
>>
>>    
>>
>>>Henry -
>>>
>>>This was a common problem back in the 60's.  You were transmitting at 
>>>14.040 MHz.  The problem is that with the S-Line you have to remove the 
>>>cables and replace the 100 ohm dummy load in the transmitter to operate 
>>>split across a bandswitch division.   We used to hear quite a few 
>>>Collins stations calling a DX station on SSB, down at the bottom of the 
>>>CW band!  None of the other brands (Drake, Heath, etc.) had the problem, 
>>>because they had 500 kHz bands.
>>>
>>>73, Garey - K4OAH
>>>Atlanta
>>>   
>>>
>>>      
>>>
>>It isn't necessary to remove ALL the cables. Just the crystal oscillator
>>cable between transmitter and receiver, and then plug the transmitter
>>oscillator internal short cable to the transmitter first oscillator
>>jack. That jack is J7 in the transmitter. Its OK to unhook that cable
>>    
>>
>>from the Jack J1 in the receiver and put in the dummy load but not
>  
>
>>absolutely necessary.
>>
>>That simple change will let you use separate crystals for transmit and
>>receive and to split any amount. But if you switch to transceive on the
>>transmitter you probably won't receive and transmit on the same
>>frequency because of the differences between the crystals even for the
>>same band segment.
>>
>> 
>>
>>    
>>
>Dr. Jerry is of course correct!  :-)   I didn't recall the specific 
>cable, I'm more familiar with the Drake scheme.   As he says, without 
>the crystal oscillator cable you are relying upon the two crystals in 
>the receiver and transmitter to be on the same frequency for "true" 
>transceive. 
>
>This was the downside of the Drake system prior to the C Line.  There 
>was a trimmer in the receiver to "net" the receiver crystal to the 
>transmitter crystal for transceive.  Only problem was that as soon as 
>the temperature changed a bit, the crystals had different T/C curves and 
>moved apart, (or not!).  Drake's answer in the late "A" and all "B" 
>series was color coded crystals characterized for similar T/C slopes.  
>The "letter" at the end of serial numbers (Red, Green, Blue and Yellow,) 
>id'd the crystal in each receiver and transmitter and if you had the 
>same letter on both, they tracked well enough over temperature.  In the 
>"C" line the two oscillators were coupled together with a new cable, 
>enabling a sort of phase lock between the two oscillators and solving 
>the problem.
>
>73, Garey - K4OAH
>Atlanta
>
>______________________________________________________________
>Collins mailing list
>Home: http://mailman.qth.net/mailman/listinfo/collins
>Help: http://mailman.qth.net/mmfaq.html
>Post: mailto:Collins at mailman.qth.net
>
>
>
>  
>