[Milsurplus] LO DF ing

[Richard]

One way to back-couple to the antenna is through tube inter-electrode 
capacitance, so a grounded grid stage would be better, but I thing stray 
coupling in the wiring would be more efficient.  I still think a 
properly operated regen won't radiate much if any.  it's weakly 
oscillating and lightly coupled to the antenna, so the modern 
superhetrodyne with a vigorous LO might be a better candidate.  Note 
that as frequency goes up this becomes a more serious problem, which 
points at tube capacitance and stray coupling.

Richard, AA1P


On 08/25/2016 03:38 PM, Mike Feher wrote:
>
> Unless those front end RF stages you are talking about were of the 
> grounded grid type, they had very little isolation of the LO. 73 – Mike
>
> Mike B. Feher, N4FS
>
> 89 Arnold Blvd.
>
> Howell, NJ, 07731
>
> 732-886-5960
>
> *From:*Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] *On 
> Behalf Of *Hubert Miller
> *Sent:* Thursday, August 25, 2016 3:34 PM
> *To:* Milsurplus at mailman.qth.net
> *Subject:* Re: [Milsurplus] LO DF ing
>
> The only instances i have read about where a regen receiver has been 
> heard at some distance has been something like “my Knight-Kit ‘Space 
> Spanner’
>
> was heard all the way across town”.  I suggest any receiver with an RF 
> stage, regen or super, could not be heard at any distance beyond 
> optical distance
>
> anyway. If this is correct, the only remaining case is where a simple 
> regen receiver with the oscillating detector coupled right to the 
> antenna. How many
>
> of these were still in use by 1940 is the question, and if any 
> remained, how quickly were they replaced. The SW-3s, Sargent 10s, 
> Marconi 730, International
>
> Marine Co. regens all did have RF stages. And as AF6IM pointed out, 
> getting a bearing on a weak signal is another challenge. It appears 
> the evidence for any successes
>
> using such technique is actually nonexistent and at best, highly 
> unlikely.  A part of folklore now about WW2, maybe.
>
> -H
>
>
>
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