[Milsurplus] SCR-269 & SCR-273 differences

[Bruce Gentry]

On 4/12/13 4:33 PM, Bruce Gentry wrote:
> On 4/11/13 7:02 PM, Dave wrote:
>> G'day all,
>>
>> I have a query about the differences between components of these two 
>> Radio Compass systems. SCR-269-* was used in aircraft with 12 or 24V 
>> electrics whereas the SCR-273-* appears to be (more or less) the 
>> equivalent for use in aircraft with only 12V electrics. The component 
>> of each system are as set out below - other components not mentioned 
>> such as cords and tuning cable/fittings are common to each system.
>>
>> The receivers do have different frequency ranges.
>>
>> My question is, why the different indicator units? I thought it might 
>> be just different illumination bulb voltages but the SCR-269 can be 
>> used on both 12 and 24v anyway. Functionally, can I use the 269 
>> indicators on the 273?
>>
>> I would like to build up functioning systems for both SCR-269 and 
>> SCR-273. I do have all the components for the 269 and I have the 
>> receiver for the 273
>>
>> I would be interested to hear from anyone who has spare components 
>> for the SCR-273 system particularly the control box BC-414. The two 
>> control boxes look identical except for the tuning ranges.
>>
>>
>> SCR-269 (12/24 volt)
>> Frequency ranges Band 1 - 200 to 410kc, Band 2 - 410 to 850kc, Band 3 
>> - 850 to 1750kc.
>>
>> BC-433* receiver
>> BC-434* control box
>> LP-21* loop antenna
>> BK-22* relay
>> I-82* indicator Navigators
>> I-81* indicator Pilots
>> PL-112 connector
>>
>>
>> SCR-273 (12 volt)
>> Frequency ranges Band 1 - 150 to 325kc, Band 2 - 325 to 695kc, Band 3 
>> - 695 to 1500kc.
>>
>> BC-413* receiver
>> BC-414* control box
>> LP-19* loop antenna
>> BK-21* relay
>> I-75* indicator Navigators
>> I-65* indicator Pilots
>> PL-117 connector
>>
>> Cheers
>> Dave
>> VK4KDP
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> In 1967, I got what was labeled a BC- 433 receiver from Fair Radio. It 
> used  24 volts DC as it's only power, had a dynamotor for high 
> voltage, and did not have any sort of automatic function. It was the 
> same size and had an almost identical case and front panel to the  
> ARN-7, but used a manually directed loop and had a "Left-Right" 
> indicator for the pilot, essentially a repackaged  MN-26.  Has anyone 
> ever seen one of these, even better, does anyone have one they are 
> willing to part with?    Thanks,
>
>  Bruce Gentry,    KA2IVY
>