[Amps] Serious design stage

R.Measures r at somis.org
Thu Apr 22 09:18:18 EDT 2004


On Apr 21, 2004, at 3:35 PM, AA6DX wrote:

> Hmmm.  OK .. guess everything is bigger in Tejas ... including Ohm's=20=

> law!
> HIHI ...
> Let's do a "what-if" ...   IF you had 24=AF VAC Single ~ --- you ran =
it=20
> down
> 25' of #16 copper ... and you were running a "Tejas KW", of 5.7 KW=20
> input,
> key down (say, FM, RTTY, Digital, AM, or CW with a brick on the key) =
--
> which should get the 1.5KW legal output rather handily, actually more=20=

> like
> 3+KW .... a single 4-1=AF=AF=AF does 2.5 KW handily, capable of a wee =
bit=20
> more ...
> depending on amp design, of course ...   THAT would require 25 amps. =20=

> So, we
> have 24=AF V, 25 amps, 25 feet of "waaaarrrrr" ...  AWG 16  ---   the=20=

> voltage
> drop would be ...   tah dah!   6.1 volts.

=F0  With a resonant-choke filter, pretty close.  With a C-filter, not=20=

even in the ballpark.  Phil knows the score.


> 233.9 VAC delivered to the xfmr.   Do the math, Phil ...
> By the way, of course, on the OTHER hand, by increasing the wire size=20=

> to
> #1=AF,   there is considerably less voltage drop .... you get 4.6 more
> olts  -  All the way to 238.5 at the business end!  Mind you, this is
> assuming you're running over 5KW input to the amplifier.    About 1=AF=AF=
=20
> Volts
> on the output side  -----  again, if you are running 5.7 KW.  By the=20=

> time
> the rest of the power supply components get into the mix ... the caps,=20=

> the
> choke(s), the diode losses, the bleeders, metering, etc .... that=20
> voltage
> difference is essentially nil.   (With number 4, you would only lose=20=

> about
> 1/2 volt.)
> But, you are correct ... if one is to run a 4CX-1=AF=AF=AF=AF at full =
tilt,=20
> you need
> some serious "waarrrrr".  Holy Cow, the filaments require over 56=AF=20=

> watts! As
> to rewiring the ham shack ... does the term "3-Phase" strike a bell?

=F0  Maybe for the 8171's big brother, the 8281, but the li'l brother =
can=20
be run easily on SSB from 1-phase 240v -- provided it is tuned up with=20=

a tuning-pulser.

> You might want to consider some other coax too .. Andrews line, with=20=

> dryer!
> The first FM transmitter that I was chief for used one of these ...

=F0  For 20m, RG-213 can handle an 8171 on anything but full-bore RTTY.

> Cheers, tnx conversation ..
>
>
> From: "Phil Clements" <philk5pc at tyler.net>
> To: "AA6DX" <aa6dx at pacbell.net>; "Jim Isbell"
> <millenniumfalcon at cableone.net>; "Mail list Amplifiers"
> <amps at contesting.com>
> Sent: Wednesday, April 21, 2004 2:19 PM
> Subject: Re: [Amps] Serious design stage
>
>
>>
>>
>>
>>> Hmmm .. just wonder why the large wire requirement, Phil?  We are
>> not
>>> connecting a restaurant size `lectric range here.  Assuming we are
>> talking
>>> AWG size wiring, the current carrying capabilities @ 230-240 VAC,
>> single ~
>>> is about:
>>> #4 =3D 37,000 watts
>>> #6 =3D 27,000 watts
>>> #10=3D 13,800 watts
>>> #16=3D 5,750 watts
>>> (Approximately, safely ... your mileage may vary!)
>>> Is that not correct?
>>
>> That is not correct because you did not specify a length.
>>
>> I don't like warm wiring inside my walls, so I spring for a few bucks
>> more for cable
>> when I wire a ham shack. My service here is 37 kva from the street
>> transformer.
>> The power company chose to run size 0 wires for the 50 foot run to my
>> service
>> entrance panel. I guess we are conservatives down here in Texas!
>>
>> The bottom line is that you do not want anymore system voltage drop
>> than is absolutely
>> necessary.
>>
>> I was also advising the wire size not for a 4-1000A, but for the
>> monster transformer
>> the guy has there. If Rich convinces him to try a 8171 amp at a later
>> date, he will not have to
>> rewire the ham shack.
>>
>> (((73)))
>> Phil, K5PC
>>
>>
>>
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
Rich Measures, AG6K, 805.386.3734.  www.somis.org/



More information about the Amps mailing list