Colin,
Are you sayin, "he's a poet and didn't know it"?
LOL
Will
*********** REPLY SEPARATOR ***********
On 8/26/05 at 8:48 AM Colin Lamb wrote:
>When I see such lines as:
>
>It is not an old wives tale,
>that a poorly made choke will fail
>
>and
>
>to avoid burning your hair,
>park your resonances with care
>
>I see something poetic just behind the grid dip meter.
>
>C'mon, where are the poets when we need them.
>
>Colin K7FM
>
>-----Original Message-----
>From: Will Matney <craxd1@verizon.net>
>Sent: Aug 26, 2005 8:28 AM
>To: amps@contesting.com
>Subject: Re: [Amps] plate choke
>
>
>On 8/26/05 at 4:00 AM R.Measures wrote:
>
>>On Aug 26, 2005, at 12:48 AM, Alex Eban wrote:
>>
>>> The main problem stems from the 160 meters operation!
>>> For the higher bands, chokes are usually in the range of 68 to 100
>>> microhenries. These are easily wound in a solenoid manner and if you
>>> space
>>> wind the last 20 turns or so, chances are you get a choke without
>>> resonances
>>> in the ham bands. On the other hand for 1.8 MHz operation the coil
>>> inductance goes up in the millihenry range: a lot of turns, crammed
>>> together. This is prone to parasitic resonances and usually you will
>>> find
>>> that the better amplifiers DO NOT include the top band, or else, they
>>> have
>>> some queer arrangement, like two chokes in series or some oddly wound
>>> choke.
>>> I remember very well the one made by Barker and Williamson , wound in
>>> sections, each on of a different number of turns.
>>
>>I tested this idea by winding two chokes, One had a continuous
>>single-layer, and one had various gaps as per the Handbook. The
>>inductances were about the same and, to my surprise, so were the
>>resonances. This led me to conclude that end-to-end coils do not
>>decouple unless the gaps are quite substantial.
>>-- For maximal decoupling, chokes need to mounted at right-angles.
>>-- For maximal coupling, chokes need to be mounted end-to-end.
>
>
>Exactly! I always thought those coils were still way too close together to
>do any good. The gaps are only around 1/4-1/2" apart. The theory I'd say
>is correct, but the design was wrong. That can be proven using a dip meter
>running either paralell or at a right angle to a coil under test. At a
>right angle, the dip meter wont couple and work.
>
>>
>>> At some time Collins used
>>> them in military radios that covered 2 to 30 MHz continuously. I don't
>>> know
>>> whether someone is making them today. This was on of the main reasons
>>> that
>>> in military equipment (high power!) they dispensed with the choke and
>>> moved
>>> over to series feeding of the high voltage supply. The GRC 106 was one
>>> good
>>> example. It employed series feed of the 2400 VDC supply and took the
>>> power
>>> out through a link on the coil.
>>> Alex 4Z5KS
>>>
>>> --
>>> No virus found in this outgoing message.
>>> Checked by AVG Anti-Virus.
>>> Version: 7.0.344 / Virus Database: 267.10.15/81 - Release Date:
>>> 8/24/2005
>>>
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>
>>Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>>
>>_______________________________________________
>>Amps mailing list
>>Amps@contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>
>
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|