Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1] 2 3 4 5 Next   Go Down
  Print  
Author Topic: Is 500 Watts worth the cost?  (Read 88501 times)
W2BLC
Member

Posts: 29




Ignore
« on: July 30, 2014, 02:26:33 PM »

This is an opinion and experience question for the 75 and 40 meter gang - not a scientific db gain question.

In your experience on 75 and 40 meters sideband, is the difference at the receiving end of the QSO at 500 Watts significantly improved using 500 Watts compared to 100 Watts? In theory, the gain should be a tad over 6 db.

To get this started, I have been making "with" and "without" the 500 Watt amplifier for several months. My findings have been dismal. Dismal in the number of stations reporting a real increase in received signal strength. Most reports indicate a difference on the S-meter, but not a difference in what is being heard. And, the meter difference is small.

This makes me think that - in most instances - the 500 Watt amplifier is not pulling its weight on a cost/value/performance scale.

I look forward to reading what others have experienced.

Bill W2BLC
Logged
AA4PB
Member

Posts: 14935




Ignore
« Reply #1 on: July 30, 2014, 03:09:48 PM »

6dB is only 1 S-unit on an accurately calibrated meter so I wouldn't expect to see much difference on the meter.
Logged

Bob  AA4PB
Garrisonville, VA
WB6BYU
Member

Posts: 18278




Ignore
« Reply #2 on: July 30, 2014, 03:33:43 PM »

When signals are S9 + 20dB, and the noise floor is S4, the amp won't make much difference.

When the signals are right at the noise floor, 6dB can make a big difference in reception.

Until conditions are poor enough that you are loosing intelligibility, adding an amp won't change
the percentage of your transmission that the other station can copy, even if the signal is stronger.
Logged
W7AIT
Member

Posts: 503




Ignore
« Reply #3 on: July 30, 2014, 03:41:54 PM »

500 WATT AMPS ARE ABOUT 6-7 DB GAIN.  FULL GALLON ADDS ANOTHER 4 DB, BUT FULL GALLON AMPS ARE AT LEAST DOUBLE THE COST.  JUST IN COST BASIS ALONE, FOR ME, THE 500 WATT AMP MORE THAN JUSTIFIES ITS COST AS IT HAS A HIGH REWARDS VS COST RATIO.

THE FULL GALLON AMPS ARE MUCH HEAVIER, TAKE UP LOTS OF SPACE, OFTEN REQUIRE 220 WIRING AND THE  COST ASSOCIATED WITH THAT, BEEFIER ANTENNAS AND RF PATH REQUIRED, THEY REALLY PLAY HAVOCK IF YOU HAVE TVI OR RFI, FAILURE RATES ARE ALSO VERY HIGH, MTBF MUCH LOWER, YOU GET PROBLEMS SUCH AS ARCING, MELTING OF TRANSMISSION LINE AND TRANSMISSION LINE COMPONENTS, TUNERS ETC., NEED A FULL GALLON RATED ANTENNA ETC. ALL OF THIS ARE REAL PROBLEMS WITH FULL GALLON AMPS.

MY EXPERINCE USING MY KPA500 AMP:  SOMETIMES NO DIFFERENCE, SOMETIMES IT MAKES ALL THE DIFFERENCE- CAN'T BE HEARD AT ALL WITH 100 WATTS BUT COPYABLE AND QSO COMPLETED WHEN AMP TURNED ON AND I HAVE THE BENEFIT OF THAT 6DB (1 S-UNIT), I MAKE THE QSO VS NOT MAKING THE QSO.

IF YOU THINK YOU WILL SEE HUGE INCREASES IN SIGNAL STRENGTH AMP ON VS AMP OFF, NO WAY, ITS EITHER 1 S-UNIT OR 1.5 S-UNIT AND THAT'S IT.

FOR YEARS I WAS PROPONENT OF 100 WATTS AND MAKE A BETTER ANTENNA BUT I'VE MAXED OUT ANTENNA HERE.  SO THAT 1 S-UNIT KPA500 MAKES ALL THE DIFFERENCE MOST OF THE TIME. 

I ALSO RUN MINE 18 HOURS A DAY, NO PROBLEMS.

FOR ME IT WAS A WISE PURCHASE WITH A HIGH BENEFIT COST RATIO.  I DID SPEND THE EXTRA MONEY AND BOUGHT THE ELECRAFT AMP, SOLID STATE, NO TUNE, BULLET PROOF, SELF PROTECTING AMP AND HAD NO PRIOBLEMS.  THIS VS THIRD ALS 600 THAT KEPT BLOWING UP THE POWER SUPPLY IN IDLE. 

I ADDED THE KAT500 TUNER AND IT WORKS VERY WELL AGAIN BULLET PROOF, NO BURNED UP PARTS OR ANTENNAS. 

MY OBSERVATIONS.

YOU SITUATION MIGHT BE DIFFERENT.
Logged
W3RSW
Member

Posts: 602




Ignore
« Reply #4 on: July 30, 2014, 03:48:42 PM »

Might be worthwhile to ask those using 500 watt amps to turn them off and see the difference in summer conditions when background is noisier. Sometimes it just takes the fatigue out of listening.  Many running amps consider them "courtesy to the listener amps." In audio 3db is about the point of increase for a good perception that signal is louder. 6db sounds like a real increase and if that is above a constant background then the increase sure can't hurt.

No one seems to ask if 1500 is worthwhile (from a perception standpoint, cost another concern ,) and that is a few db above 500.

Many say that the first 500 is the most important. ..and at least cost for an amp along with the possible decrease in IM since the driver is running a somewhat reduced power than the normal 100.

Also in simply seeking out CQ's to answer, listeners really trend to answer the louder signals, especially when seen in spectrum on an SDR.  Human nature unless niche ops or contesting.
Hanging out with the gang on set frequencies also tends to influence one to keep up with the pack. Don't want any weak monikers attached to our lash up, heh, heh.

Oh, also meant to mention that 500 or 600 PEP ( what a good 500 w Rated amp ('7AIT's) delivers with little strain) is simply what a 100 watt AM transmitter of yore delivered along with the constant carrier suppression of background noise. Yes, having all 450 to 600 watts PEP in one sideband is superior in many respects and for far a lot of reasons at least approaches the common, medium power of the bulk of seasoned hams back in the days of AM.
« Last Edit: July 30, 2014, 04:04:40 PM by W3RSW » Logged

Rick, W3RSW
K6AER
Member

Posts: 5617




Ignore
« Reply #5 on: July 30, 2014, 04:04:01 PM »

Call CQ without the amp and then call CQ with the amp. I notice when calling with the amp I get a lot of replay's. With out the amp sometimes I call several times. Most hams have a very high noise level and their antennas are not efficient. Especially on 40 and 80.

As BYU had mention, it come down to carrier to noise ratio. When you signal is only 6 dB above the noise floor another 6 dB makes a a big difference.
Logged
W8MW
Member

Posts: 343




Ignore
« Reply #6 on: July 30, 2014, 04:34:12 PM »

>In your experience on 75 and 40 meters sideband, is the difference at the receiving end of the QSO at 500 Watts significantly improved using 500 Watts compared to 100 Watts?

52 years on 75 SSB.  Amplified signals deliver comfortable listening for your contacts.  If you become a regular in group or net operation, it's courteous for you to provide your buddies with enough signal they don't have to strain.   

I've heard exceptions.  People in an exceptionally good location or with an exceptionally good antenna can run barefoot and be competitive with the amplified crowd.  It's rare. 

73 Mike W8MW
Logged
WB2EOD
Member

Posts: 263




Ignore
« Reply #7 on: July 30, 2014, 05:08:07 PM »

From 100 to 500 watts yields 6db, about 1 s-unit. 
If the other operator is copying you at s2 or s3, 500 watts could be the difference between working him or missing him. 
The real "bang for the buck" is 600-800 watts, beyond which, the cost per watt rises dramatically.
Going from 800 watts to the legal limit will get you less than 1 s-unit which may not be worth the money. 
If you are working a station at the bottom of a pileup, extra power can give you a definite "edge"
Ameritron makes reasonably priced tube and solid state amplifiers that do 600 to 800 watts.
I own an AL-811H but I don't use it routinely. 
With all the power in the world, you can't work what you can't hear.

73
WB2EOD
Logged
KD8MJR
Member

Posts: 5449




Ignore
« Reply #8 on: July 30, 2014, 07:24:01 PM »

When signals are S9 + 20dB, and the noise floor is S4, the amp won't make much difference.

When the signals are right at the noise floor, 6dB can make a big difference in reception.

Until conditions are poor enough that you are loosing intelligibility, adding an amp won't change
the percentage of your transmission that the other station can copy, even if the signal is stronger.

That's exactly what I have also found.
Using a 500w amp in the right conditions is the difference between nothing heard and getting back a 44 or 54 report.
Logged

“A lie can travel half way around the world while the truth is putting on its shoes.”  (Mark Twain)
N3DT
Member

Posts: 1595




Ignore
« Reply #9 on: July 30, 2014, 07:28:33 PM »

100 to 500 W is 6.99dB, just over an S unit if it's calibrated right. 100 to 1KW is 10 dB, less than 2 S units if calibrated. 1500W is real close to 12 dB, or 2 S units.  Your choice.  The AL80B you can find for a buck a watt if you look around and it's really good for 800W, or 9 dB. It'll push a KW but who hears 1 dB?  How much do you want to spend, and don't forget all the peripherals that the extra power requires.  Improve the antenna first.  You can gain 2 S units going to a 70' inverted V vs. a ground mounted vertical or ground plane, I know I've tried them. Height is everything.  A beam will do even more if it's up enough.
Logged
N0NZG
Member

Posts: 127




Ignore
« Reply #10 on: July 30, 2014, 08:22:09 PM »

I have found that on the 75/80 meter rag chew nets were most of my communication is NVIS the first 500 to 800 watts makes all the difference. With 100 watts sometimes I am lucky if 10% of the check-ins  around the country can hear my station then when I turn on the amp I am guessing about 60 to 80 percent of the total check-ins can hear me.  On 75/80 meters I have a dipole that is only 20 feet off the ground.  Then on 40 meters I have a ground mounted vertical with about 40 radials. When on the triple H, W A S or other DX net I find an amplifier is mandatory.  IMHO unless you are going to blatantly disregard  the FCC power limitations most stations are well served with a 500 to 800 watt amplifier as others have said  going from 800 watts to 1500 watts will in 90% of all cases not make a difference on the receiving end.  Adding that extra power if fraught with challenges in the areas of feed lines, antennas, antenna tuners, the need for 240 volt power for your amplifier, a bigger dummy load etc. Most of the time my amp is running 800 watts output t ,however I will also admit when that rare DX station shows up I will like many others load my amp for as many watts as she will put out to get that contact.  Does it make much difference probably NOT ! 

73, Jeremy
Logged
KM3F
Member

Posts: 902




Ignore
« Reply #11 on: July 30, 2014, 09:07:34 PM »

Looking at it from a different perspective; if you go to 40m in the daytime and listen to the ECARS net on 7.255, you will hear a variety of power levels from which to help make a judgment.
Conditions have been unusually tough for quite some time.
The net controllers have a hard time with QRP and mobile station very often because the Mobiles and QRPS can hear but cannot be heard well .
This is an example of a mobiles with less than about a 5% efficiency out of 100 watts being about the same as a 5 watt QRP on a full size antenna with much higher efficiency.
I am not downing QRP or bare foot operation because under favorable conditions these stations put up a strong signal but also get lost to QSB conditions where the contact is lost to interrupt the activity.
Basically for this use you should use some power to help the net controller from missing you, poor copy, excessive noise on either end and excessive repeating.
Often when this is the case a relay is asked for.
There are di hard QRPers and low power addicts as a personal challenge but sometimes you have to be reasonable about it.
I would evaluate these kinds of issues after hearing them over a few weeks time then decide.
My preference is to have my AL80B on when working nets such as these..
Forget about the S unit gains or losses. Make your time and effort  worthwhile by being heard reasonably well.
I don't think we practice this hobby according to an S meter reading but by being heard and hearing the other end respond.
Good luck..
Logged
W6GX
Member

Posts: 232




Ignore
« Reply #12 on: July 30, 2014, 09:24:27 PM »

I work DX primarily and I enjoy working pile ups.  In a big pileup even a small increase in power makes a huge difference.  This is because there are hundreds of stations and you just need to be a tad louder then your signal will rise above the rest of them.  I went from 600w to 1500w (4db) and the difference is night and day in breaking a pileup.

73,
Jonathan W6GX
Logged
W8GP
Member

Posts: 353




Ignore
« Reply #13 on: July 31, 2014, 08:22:30 AM »

500 watts is worthwhile, but 800 is better. Whether it's worth the cost depends on the cost!
Logged
W8JX
Member

Posts: 13268




Ignore
« Reply #14 on: July 31, 2014, 08:50:42 AM »

500 watts is worthwhile, but 800 is better. Whether it's worth the cost depends on the cost!


800 is a good number and adds 9db. Going from there to legal limit adds only 3 db more. 
Logged

--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
Pages: [1] 2 3 4 5 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!