[ARC5] ARC5 Digest, Vol 105, Issue 155

Thu Oct 25 22:32:20 EDT 2012

On Mk II sets, the dyno runs all the time. The dyno only spools up
transmit on the Canadian Mk III sets with the Vibrator PS.

-John

==============

> Hi guys i had a 19set #2 M xyl and 3 cats were in the basement when i
> sterted the dynamotor the cats took off to hide under a bed my xyl shook
> her head as she left the basement owell      73    darryl    ve3cpo
>
> On Thu, Oct 25, 2012 at 12:53 AM, <arc5-request at mailman.qth.net> wrote:
>
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>> Today's Topics:
>>
>>    1. Re: Why an UNUN? (Neil)
>>    2. Re: Why an UNUN? (Neil)
>>    3. Re: Why an UNUN? (Mike Feher)
>>    4. Re: Why an UNUN? (J. Forster)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Thu, 25 Oct 2012 15:58:21 +1300
>> From: "Neil" <neilb at ihug.co.nz>
>> Subject: Re: [ARC5] Why an UNUN?
>> To: "arc5" <arc5 at mailman.qth.net>
>> Message-ID: <338D1B49C9D640969376EEC1D3C96068 at neilb>
>> Content-Type: text/plain;       charset="iso-8859-1"
>>
>> > The 13 seems a bit high. Is there a lower limit given also? I don't
>> have
>> > that manual to hand.
>>
>> I've seen a figure of 5 ohms, but I can't recall where.
>> Most likely on this very forum.
>>
>> 73 de Neil ZL1ANM
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Thu, 25 Oct 2012 16:03:13 +1300
>> From: "Neil" <neilb at ihug.co.nz>
>> Subject: Re: [ARC5] Why an UNUN?
>> To: "arc5" <arc5 at mailman.qth.net>
>> Message-ID: <DDCC699C353D4EEFA36F27E37DD44CA0 at neilb>
>> Content-Type: text/plain;       charset="iso-8859-1"
>>
>> > A transmitter does not present a "load" as such to the input end of a
>> > transmission line.
>>
>> Actually it does, to the power reflected from a mismatch.
>> And in the real world, there is ALWAYS reflected power,
>> no matter how minute.
>>
>> 73 de Neil ZL1ANM
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Wed, 24 Oct 2012 23:38:11 -0400
>> From: "Mike Feher" <n4fs at eozinc.com>
>> Subject: Re: [ARC5] Why an UNUN?
>> To: "'arc5'" <arc5 at mailman.qth.net>
>> Message-ID: <[email protected]>
>> Content-Type: text/plain;       charset="us-ascii"
>>
>> About 25 or more years ago I bought a mint WS-19 at the Vienna hamfest.
>> I
>> just had to put it on the air. Read up on it and I figured I at a
>> minimum
>> needed a 1to 4 matching transformer. So, I built one. A simple coaxial
>> on a
>> toroid and placed it in a small box. Right away I was able to load up my
>> WS-19 and worked all over the place with it. Never used a series
>> capacitor.
>> When I got a BC-474A, I also used it with it with amazing results.
>> Again,
>> no
>> capacitor. Then came a brand new TCS, and, same results. In my opinion
>> it
>> is
>> the simplest, no mod, remedy to get a rig designed for a short antenna
>> on
>> the air.
>>
>> Mike B. Feher, N4FS
>> 89 Arnold Blvd.
>> Howell, NJ, 07731
>> 732-886-5960
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Wed, 24 Oct 2012 21:51:50 -0700 (PDT)
>> From: "J. Forster" <jfor at quikus.com>
>> Subject: Re: [ARC5] Why an UNUN?
>> To: "mac" <w7qho at aol.com>
>> Cc: ARC-5 List <arc5 at mailman.qth.net>, Mike Hanz
>>         <aaf-radio-1 at aafradio.org>
>> Message-ID:
>>         <1154.12.6.201.149.1351140710.squirrel at popaccts.quikus.com>
>> Content-Type: text/plain;charset=iso-8859-1
>>
>> >
>> >
>> >
>> >
>> >
>> > On Oct 24, 2012, at 6:45 PM, J. Forster wrote:
>> >
>> >>
>> >> Not really.
>> >
>> >
>> > Yes really
>> >
>> >
>> >>
>> >> A transmitter, like a battery or other power supply, can be modelled
>> >> as a
>> >> Thevinin Equivalenrt, an ideal Voltage Source in series with an
>> Output
>> >> Impedance.
>> >
>> >
>> > The equivalent circuit of a class C amplifier would look like an AC
>> > (RF) voltage source with a very low internal resistance.
>> >
>> >
>> >
>> >>
>> >> There is a circuit theory theorem that, for maximum real power
>> >> tranfer,
>> >> the load impedance should be equal to Complex Conjugate of the source
>> >> impedance.
>> >
>> > We're not talking about maximum power transfer here.  A Class C amp is
>> > designed to provide a particular power output at a high efficiency,
>> > not maximum power transfer which results in an efficiency of 50% .
>> > You''re thinking of class A.
>>
>> The class of the amplifies has nothing to do with the conditions for
>> maximum power transfer fron the transmitter tank to the antenna.
>>
>> -John
>>
>> ====================
>>
>> > This means equal to, if the source and load are purely resistive.
>> >
>> >>
>> >> This means if one is inductive, the other must be capacitive, and the
>> >
>> >
>> > We keep the load resistance seen by the PA tube purely resistive here
>> > with our resonant tank circuit.   In practice we strive to present the
>> > amplifier with a purely resistive load if possible. Small values of
>> > reactance reflected into the tank circuit can be accommodated by
>> > tuning adjustments.  In those cases where the reactive components are
>> > too large external antenna 'tuners" are employed.
>> >
>> >
>> >> inductive reactance equals the capacitive reactance.
>> >>
>> >> This means if the source is complex (resistive + inductive), the
>> >> load must
>> >> have a load where the resistive componants are equal and the
>> >> capacitive
>> >> reactance is equal, and opposite, to the source inductive reactance.
>> >>
>> >> ie:  The L & C are resonant at the operating frequency.
>> >
>> > See above
>> >
>> > Dennis D.  W7QHO
>> > Glendale, CA
>> >
>> >
>>
>>
>>
>>
>> ------------------------------
>>
>> _______________________________________________
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>>
>> End of ARC5 Digest, Vol 105, Issue 155
>> **************************************
>>
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