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Author Topic: High Power, High Splatter  (Read 1600 times)
W8ZNX
Member

Posts: 1




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« Reply #15 on: October 31, 2008, 01:53:16 AM »

ad4u
you did say 5 kw dc into a dummy load

not 5 kw dc input to the final stage

high power has nothing to do with it

running 1 kw, 10 kw or 50 kw makes no matter

a 75 watt signal can be wide dirty
50 kw signal can be tight and clean

it all has to do with how it is run

along with
how well the receiver can handle strong signals
and does the op know how to use the receiver
lots of things can make a strong signal
seem to be wide when its not

was your noise blanker turned on
did you try turning back rf gain

oh by the way
the FT-897 does not have much of a receiver

and
yes SCUBA
do you have a call
all real ops
use their call letters

dit dit
mac
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K0WA
Member

Posts: 95




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« Reply #16 on: October 31, 2008, 07:02:30 AM »

KB9CRY - Damn Contesters....

Before you go damning people...maybe you should think a little.  Today's HF rigs and the technology they are using has been driven by contesters demanding performance.

Contesting has kept Ham Radio alive over the past several decades. - IMHO

Contesters are good ops...and most of them are great guys and gals.  They are very good ops.  I am sure there some bad apples, but I have found very few in the 40 years I've been contesting.

So, don't damn the people who operate the contests.

Lee - K0WA
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KB9CRY
Member

Posts: 4283


WWW

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« Reply #17 on: October 31, 2008, 07:47:59 AM »

I haven't seen your call much on eHam Lee.  I know others know that I'm a contester also and love it.
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VR2AX
Member

Posts: 589




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« Reply #18 on: November 01, 2008, 08:40:06 AM »

Assumptions are generally dangerous. And more often incorrect than correct

Illegality can take many forms. Some examples might be closer to the observer than the object of observation.  

So by whose standard is 1.5kw necessarily 'legal'? Some licences worldwide still limit power to 10 watts  or so, depending on class.

10 watts can splatter too.
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AA4PB
Member

Posts: 12854




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« Reply #19 on: November 01, 2008, 11:50:13 AM »

Any contester who is really splattering all over the band obviously doesn't know what he is doing. Splattering just wastes power. He'd make a lot more contacts with a clean signal.

On the other hand, it is quite possible that with a band full of strong signals the receiver just can't handle it and the stronger signals "appear" to be splattering. That's what they make RF gain controls and attenuators for (as well as the preamp OFF switch).
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SCUBA
Member

Posts: 74




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« Reply #20 on: November 08, 2008, 11:58:43 AM »

Hi K0BG, thanks for replying and thanks for other replies as well.  The extent of my involvement was amazement in the amount of spectrum the offending station was encumbering.

For readers who noted that I use a login in lieu of a callsign, I attempted to explain in this message thread:
http://www.eham.net/forums/SiteTalk/1415?page=2

Thanks again, and 73,
Jack
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K1DA
Member

Posts: 507




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« Reply #21 on: November 12, 2008, 02:20:19 PM »

   And it's always a "BROADCAST" transmitter that is the villain.  Darn few "Broadcast" transmitters have a bandswitch on the front which lets them go from 160 -10.  Most HF broadcast transmitters are single frequency devices.  I can think of a number of sources of "non-broadcast" high power shortwave transmitters
very few of which would occur to the new generation of crackerbox license holders, such as  ex-military, civilian point to point, airline (yes, the airlines once used hf ssb for many purposes) and maritime.  What I have  noticed is there is an inverse relationship between receiver quality and number of "splatter incidents" observed, not that a mal- adjusted transmitter system won't splatter.  SSB operators used to speak with some understanding of things like exciter output, power supply headroom, tube performance curves and such.  Now it's "I can get 1500 somethings out into a dummy load", so yes, there is some splatter on the bands.  
Just check your noise blanker before you jump on a guy.  
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W8JI
Member

Posts: 9296


WWW

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« Reply #22 on: November 13, 2008, 02:06:42 AM »

What a bunch of misinformation!!!!!

First, limiter and processors often REDUCE bandwidth by holding levels constant. They certainly do not have to increase bandwidth!!

You can have all the distortion you want in the speech amplfiers and microphones and it will not make the signal wide. The distortion has to be BEYOND the filter in the transmitter to create excessive bandwidth.

The filter is normally in the transmitter IF section, unless it is a DSP rig. In a DSP rig the only way to get distortion is AFTER or in the DSP system (it contains the "filter"), not from from the audio amps.

The reason 99% of stations have excessive bandwidth is they either don't know how to tune the amplifier, they use tetrode amps or cheap solid state 12 volt amps, or they have dicked up their radios.

For example, a well-known contester in this area was bringing me his FT1000MP's for service. EVERY radio he brought had the internal power limiting pot set to allow the radio to run 130 watts PEP or more. With a zero distortion audio chain, that radio would still have terrible IMD and splatter because the POWER level was set too high. I would turn the pots back to 100 watts and the next time I would see the radio it would be right back up to 130 watts or more.

I also would not go around handing out certificate of splatter with a radio noted for having a pretty poor receiver, and I would make sure my receiver noise blanker was OFF before giving any reports!!!

I agree there are a lot of trashy signals on 20 meters. I count about one out of four with grossly excessive bandwidth. But it is usually not anything but how they tune the amps or the type of amps they have. They can run any amount of processing they like BEFORE the filtering in the transmitter or power, and it will not cause bandwidth problems. The problem is caused by flat topping stages AFTER the filtering that sets the bandwidth.

If we can't get this right and understand what really causes the problems we will never solve the problem.

73 Tom
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N6AJR
Member

Posts: 9908




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« Reply #23 on: November 17, 2008, 06:15:52 PM »

I am also a causal contester, and armchair dxer.  I am a memeber of the northern california contest club.  it is a super bunch of some of the most  honorable folks I have met.  We like to contest. I find the thought of running an outlandish amount of power is silly.

In this weekends SweepStakes phone contest, I actuall turned my output down to less than 800 watts, why you ask??  

I am running a Alpha 87 a on the main rig, the orion, and  my friend was using about 800 watts on the FT 990 and al 1200 amp.   we could operate fine  with each other on different bands with full power but  then we kept getting those darn ESP calls returning all the time.

At limit with my 3 ele steppir, I put out a fair signal to the east coast, . Folks on a 100 watt radio and a dipole can hear me fine. but when they come back they can barely be heard out here.  

so if you cut the powe down by half,  a lot less ESP calls come in and I can run a little faster.  I may use 1500 watts on shooting DX, but in day to day and in a contest, I will usually run a lot less power than I could.  I don't know if this makes sense to you but it works for me.    all the knobs all the way to the right is not they way to keep you equipment from breaking or you fellow hams
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