[Boatanchors] Cheap & Easy Selectivity

[Carl]

Gimmick is more correctly applied to any capacitor created by using 2 wires 
as the plates. Tightly twisted is simply one of several configurations. The 
term can be stretched a bit when a vacuum tube plate is used as one of the 
capacitor plates.

The term goes back to the early 30's at least.

Carl
KM1H

----- Original Message ----- 
From: "J. Forster" <jfor at quik.com>
To: "Carl" <km1h at jeremy.mv.com>
Cc: "Boatanchors" <boatanchors at mailman.qth.net>
Sent: Thursday, August 20, 2009 6:13 PM
Subject: Re: [Boatanchors] Cheap & Easy Selectivity


> The term 'gimmick' is more usually applied to a pair of solid, insulated
> wire (like hookup or magnet) twisted together fairly tightly. One pair of
> ends are the capacitor terminals. The other ends are just cut off.
>
> The capacitance may be adjusted down by snipping bits off the unconnected
> ends, or by untwisting a bit.
>
> -John
>
> =================
>
>
>
>> Its also called a "gimmick" capacitor. Its even used in commercial 
>> radios.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message -----
>> From: "rbethman" <rbethman at comcast.net>
>> To: "Boatanchors" <boatanchors at mailman.qth.net>
>> Cc: "AI2Q" <ai2q at roadrunner.com>
>> Sent: Thursday, August 20, 2009 2:51 PM
>> Subject: Re: [Boatanchors] Cheap & Easy Selectivity
>>
>>
>>> The Handbook say to use a "short wire", attached to the grid, and add a
>>> small amount of capacitance, creating feedback by bring the loose end in
>>> near proximity to the plate lead.
>>>
>>> This is a paraphrased condensation of the several paragraphs.
>>>
>>> Bob - N0DGN
>>>
>>> AI2Q wrote:
>>>> Sounds like what a Q-multiplier box does.
>>>>
>>>> Vy 73, AI2Q, Alex
>>>>
>>>> ----- Original Message ----- From: "rbethman" <rbethman at comcast.net>
>>>> To: "Boatanchors" <boatanchors at mailman.qth.net>
>>>> Sent: Thursday, August 20, 2009 2:19 PM
>>>> Subject: Re: [Boatanchors] Cheap & Easy Selectivity
>>>>> The 1948 ARRL handbook hits it in Chap 5,  High Frequency Receivers,
>>>>> Improving Receiver Selectivity, IF Amplifiers, then under a minor
>>>>> heading:  Regeneraton.  pp115-116.
>>>>>
>>>>> This is essentially ADDING Regen to a Superhet.
>>>>>
>>>>> Bob - N0DGN
>>>
>>> ______________________________________________________________
>>> Boatanchors mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Boatanchors at mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>> ______________________________________________________________
>> Boatanchors mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Boatanchors at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>
>