[600MRG] Amp

[Charles Conner]

GREETINGS folks:    I hear a lot of chatter about this "Linear and that "
linear.

JMA, If your linear is really linear, the efficency is around 30% .
If the same linear is operated as Class C, the "bias" has to be 4 times
more than the bias value above (AB1 ??) Only then will the effiency
approach 70 %. Clean CW signals work well with "linear"s . The CW
signal should  be as clean as any other good  mode. If you want to hear
some distortion of digital signals, Just listen for over driven inputs
with any mode. , including CW.

PS;  Surplus or new distortion measurement are available to measure
any mode of distortion. A good scope is good to see distortion also.
JMOP es 73,   Charlie, K0NG   ..


On Mon, Aug 3, 2015 at 2:59 PM, <kl7aj at acsalaska.net> wrote:

> Your mileage may vary here:
>
> When I was working at HIPAS, we had an experimental VLF setup for some
> data exchange.  We used a loaded 30 foot vertical driven directly with a
> pulse generator.  The Q of the antenna (in the 180kHz range, as I recall)
> was so high that it was a pure sine wave being emitted from the antenna.  I
> would imagine tthat 90% of the antennas used on this experiment would
> exhibit the same properties!   Of couse you want to check it out, but I
> think you'll see the same thing.
> Eric
>
>
> On Mon, 3 Aug 2015 14:55:11 -0500, John Langridge <kb5njd at gmail.com>
> wrote:
>
>> Please remember that at HF, at least, clicks can be not only accentuated,
>> but
>> even generated, by propagation effects. In my 59 years as a ham, I have
>> heard this effect often. I spend most of my ham time on CW.
>> Ken, you make a really good point here... Taking it a few steps further.
>> While the engineer will want to optimize ad infinitum, at the end of the
>> day its going to be a mountain out a mole hill because few stations will
>> actually be loud enough on a consistent basis to be a real issue. And
>> thats another point that has been made time and time again over the years
>> on the topband reflector. While key clicks can impact anyone, the most
>> egregious offenders are the ones that are the loudest... right or wrong to
>> ignore? that's a different question entirely...
>> I've never heard anyone with key clicks on 630m after being on the air
>> just
>> about every night since 2012... and its not because there is no CW
>> running... its because signals are either sufficiently weak that the
>> clicks
>> are not heard or they are not present.
>> 73,
>>
>> john
>>
>>
>>
>>
>> On Mon, Aug 3, 2015 at 2:40 PM, Kenneth G. Gordon <
>> kgordon2006 at frontier.com>
>> wrote:
>>
>> > On 3 Aug 2015 at 15:03, Jim Miller wrote:
>> >
>> > > The way I'm thinking about this is the drive to the finals (FETS
>> usually)
>> > > needs to be hard and square at 472khz in order to achieve the desired
>> > > minimum switching transition times. >
>> > I'm sorry, but I am not following you: the first question that hits me
>> is
>> > "Why?". > What type of amp are you suggesting? Why does it REQUIRE a
>> > square-wave input?
>> >
>> > > This means the drivers need to hit the
>> > > finals with a 472Khz square wave. Anything less than a square wave at
>> > this
>> > > point will result in excessive power dissipation if this is a
>> continuous
>> > > occurrence. Obviously not desirable. >
>> > Again, I am not following you here. The amp in question sounds rather
>> odd
>> > to me. >
>> > It sounds to me that rather than an amplifier, you are essentially
>> using a
>> > switching-power supply to drive an antenna. >
>> > > OTOH a finely shaped, e.g, raised cosine (ok, I know its not
>> optimal..)
>>
>> > RF
>> > > envelope coming into the amp will have around a 5ms period of rising
>> and
>> > falling
>> > > signal. How the predriver, driver and final stages deal with this ramp
>> > will
>> > > determine whether or not "key clicks" will result. >
>> > ALL amplifiers tend to "sharpen up" the wave-form applied to their
>> inputs. > Linear amplifiers tend to do this to a lesser extent, but it can
>> still
>> > happen with
>> > them too. >
>> > > It seems to me that the amp will necessarily sharpen those
>> transitions in
>> > > order to ensure than switching time at 472khz is minimized and
>> therefore
>> > > produce broader CW signals than if a linear was used. >
>> > Well, I must again ask, what kind of "amplifier" is this? It sounds
>> rather
>> > odd
>> > to me. >
>> > > This should be easy to test on the air. I have a P3 and I'm used to
>> > seeing
>> > > "clicky" CW all the time in contests. I usually see a handful of
>> 2-3khz
>> > > signals each time and occasionally a 5khz monster. >
>> > Please remember that at HF, at least, clicks can be not only
>> accentuated,
>> > but
>> > even generated, by propagation effects. In my 59 years as a ham, I have
>> > heard this effect often. I spend most of my ham time on CW. >
>> > Ken W7EKB
>> >
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