[ARC5] "ARC-5" Market Value - It's Crazy

[Joel R Roberts]

I just happen to have a QF-1 sitting in my radio room looking for a job. 
Better blow the dust off and see what we can do.....Joel KB0FPT

On 8/10/2015 8:21 PM, Phillip Carpenter wrote:
> The best reference for adding a Q multiplier to a Command Set receiver is: "Using the Q Multiplier with Military Receivers", by Don Stoner, CQ February 1957, pages 60-64. Figure 5 on page 60 lists all the coils needed for each of the different IFs of all the Command Set receivers. The basis of the Q multiplier is a Heath QF-1 that uses a 12AX7. I may very well try this simple circuit on my BC receivers.
>
> 73s,
>
> Phillip W4RTX
>
> Sent from my iPhone
>
>> On Aug 10, 2015, at 8:35 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
>>
>>> On 10 Aug 2015 at 17:52, Phillip Carpenter wrote:
>>>
>>> See: "Transistorized Q Multiplier", QST January 1958. Uses a CK768 PNP junction
>>> transistor (NTE100, 2N482, 2N309, 2N308).
>>>
>>> Phillip
>> That's it. Thanks, Phillip.
>>
>> One thing to remember about that circuit though, is that it uses "parallel" feed
>> of the DC to the transistor. My friend tried to use a modern 10 mH choke
>> there, and its "Q" was so high that the "Q" multiplier oscillated at something
>> like 10 KHz instead of 455 KHz. He had to go to a series DC feed, and that
>> fixed it.
>>
>> He told me that in his RME-69, it works very well.
>>
>> Ken W7EKB
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