1500w Mobile
 

It's that mad time of year.

Wanting to move up from my current Metron mobile amp what thoughts on
basic layout of a 14v DC powered amp that could run the full legal
limit?

Would you run say, 16 Toshiba 2SC2879 devices (within their total
dissipation specs) to keep IMD halfway reasonable or would you
consider an on-board switcher PSU up to say 80-100v to use some more
modern FET's. Is this at all feasable?

Of course a 'stiff' DC supply is required whichever way you go and the
extra few dB in signal is questionable as to whether it's worth all
the trouble.

I think a Hi-Q antenna would handle the power so that's not a concern.

Your thoughts on "Son of Metron".

Phil G4ZOW

1500w Mobile
 

In article . com,
wrote:

Wanting to move up from my current Metron mobile amp what thoughts on
basic layout of a 14v DC powered amp that could run the full legal
limit?

Phil-

I'd say you would be better off with a portable generator riding along
to provide power to a 120 or 240 VAC amplifier. This would be easy if
you had a mobile home, since it may have the generator already.

For 1000 Watts DC, you would draw 71 Amps. Throw in an efficiency
factor and you might be up to 100 Amps. By going with the AC generator,
your current is more manageable with around 12 Amps at 120 VAC or 6 Amps
at 240 VAC.

Check out the Honda EU2000i generator, which is capable of supplying a
continuous 1600 watts at 120 VAC. It would be neat if you could mount
it outside and feed it from your vehicle gas tank. (It is also a very
quiet generator.)

Fred
K4DII

1500w Mobile
 

Hi Fred,

I hear what you say but I really don't wish to tow anything let alone
a genny.

I've experience with high output charging systems and split charging
circuitry and have no problems supplying a 'stiff' 14v at a few
hundred amps.

About the only good thing about running QRO on sideband is that the
'average' current drain is really not that high, even with say 50%
efficiency out of the amp. Peak current is pretty high but a couple of
decent quality batteries with a good charging system see that as no
real pain.

2 X 0 or 4 X 0 welding cable is the order of the day for minimal
voltage drop and a Leece or Electrodyne alternator.

Anyhow, let's see what others have to say.

Thanks again.

Phil G4ZOW

1500w Mobile
 

1500w Mobile
 

On Mon, 20 Aug 2007 14:05:13 -0700, John Smith I
wrote:

wrote:

...
Your thoughts on "Son of Metron".

Phil G4ZOW


Fill the trunk with batteries, run two 100 amp alternators in parallel,
solid state batteries switch for the batteries and buy plenty of 0 or 00
stranded wire and expect for a lot more people to hear you then you can
hear ... blah, blah, blah.

Put the extra batteries in series, so you can use some decent
amplifiers requiring 60-100 V. Since it is unlikely that you are going
to transmit all the time, the 12/60 V battery charger inverter can be
rated at a lower power level.

While it may be possible to build mobile antennas that efficiently
radiates most of the transmitter power at VHF/UHF and perhaps on the
upper HF bands, the efficiency of a mobile antenna on the lower HF
bands is very bad, most of the power would be dissipated in the
antenna structures.

On lower HF bands, the car body is not a sufficient ground plane, so
there might be high RF voltages in the car body compared to ground,
which could cause nasty RF-burns if operated on a parking lot and
someone touches the body of the car. Also the modern electronics in
most cars might not work in such environment.

Paul OH3LWR

1500w Mobile
 

On Mon, 20 Aug 2007 06:29:52 -0700, wrote:

It's that mad time of year.

Wanting to move up from my current Metron mobile amp what thoughts on
basic layout of a 14v DC powered amp that could run the full legal
limit?

Would you run say, 16 Toshiba 2SC2879 devices (within their total
dissipation specs) to keep IMD halfway reasonable or would you
consider an on-board switcher PSU up to say 80-100v to use some more
modern FET's. Is this at all feasable?

Of course a 'stiff' DC supply is required whichever way you go and the
extra few dB in signal is questionable as to whether it's worth all
the trouble.

I'd series the batteries for 24 volts at least. That makes a much more
manageable system.

I'm currently running a KW PEP out with just 4 transistors.


I think a Hi-Q antenna would handle the power so that's not a concern.

Your thoughts on "Son of Metron".

Phil G4ZOW

1500w Mobile
 

You can run anything you want as long as you have the resources. Some 50+
years ago, in an old Radio Handbook (Bill Orr?), there was (I think) a
discussion and photographs of a 1kw SSB transceiver and it was using a
water-cooled jacketed metal ceramic tube and for extra power, a three
phase arc welder generator under the hood. The rest was a piece of cake.

P.S. the circuitry was pretty simple, but watch out for the water cooling
and pump and reservoir (not for the faint of heart).

===== no change to below, included for reference and context =====

On Mon, 20 Aug 2007, wrote:

It's that mad time of year.

Wanting to move up from my current Metron mobile amp what thoughts on
basic layout of a 14v DC powered amp that could run the full legal
limit?

Would you run say, 16 Toshiba 2SC2879 devices (within their total
dissipation specs) to keep IMD halfway reasonable or would you
consider an on-board switcher PSU up to say 80-100v to use some more
modern FET's. Is this at all feasable?

Of course a 'stiff' DC supply is required whichever way you go and the
extra few dB in signal is questionable as to whether it's worth all
the trouble.

I think a Hi-Q antenna would handle the power so that's not a concern.

Your thoughts on "Son of Metron".

Phil G4ZOW

1500w Mobile
 

Thanks for the feedback, however I'm not so much interested in
charging systems as your views on generating the RF power out of solid
state devices.

Roger,

I appreciate the advantages of running higher voltage devices but
going that route I'd prefer to convert from 14 up to at least 50v.

Do you have details of your amp anywhere up on a web page by chance.

I believe G3YXM runs a similar system.

Anyone of you into high power solid state RF design?

Phil G4ZOW

1500w Mobile
 

On Aug 22, 5:56 am, Transmitter Man wrote:
Thanks for the feedback, however I'm not so much interested in
charging systems as your views on generating the RF power out of solid
state devices.

Roger,

I appreciate the advantages of running higher voltage devices but
going that route I'd prefer to convert from 14 up to at least 50v.

Do you have details of your amp anywhere up on a web page by chance.

I believe G3YXM runs a similar system.

Anyone of you into high power solid state RF design?

Phil G4ZOW

Phil, google on 'cb high power keydown shootout pills', or similar
combinations..

Just for a hint start with:
http://www.davemade.com/mobile.htm
and
http://video.google.com/videoplay?do...52407910943036

It's a big world and most of us hams have tunnel vision...

denny

1500w Mobile
 

Personally I doubt very much your Engine Management Control Unit will
stand up to the stray RF. ;-)

Larry VE7EA

1500w Mobile
 

Hi Denny & Larry,

I'm aware of the large amp's used on 27MHz and have a heavily modified
16 device 14v CB amp in my collection with a proper bias circuit for
SSB operation. However, it's still only suitable for 10 through 15m in
it's present configuration.

I took my blinkers off around 84 when I was in the states and drove
non-stop from one 'shootout' in Tyler TX to another in the Windy
City!

Larry, My HF mobile vehicle runs an early turbo diesel engine and was
built before engine management systems were introduced. Heck, being
diesel there's not even a traditional ignition circuit to interfere
with. Receive's also nice and quiet:-)

So, without increasing PA voltage it seems one's still stuck with a
bunch of bi-polars. How technology has move on in 25 years - not.

Phil G4ZOW