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Author Topic: 100 or 200 watt radio  (Read 14438 times)
KB3FFH
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« on: October 11, 2012, 11:26:39 AM »

Is it worth it to spend the extra money to purchase a 200 watt radio instead of a 100 watt radio? I think a 200 watt radio I saw was $600 more than the 100 watt version. Thanks Bill
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KE4YOG
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« Reply #1 on: October 11, 2012, 05:41:37 PM »

I use the TS480HX. I really enjoy the rig. I feel the extra 100 watts helps at times but I am not sure it is 600 dollars worth. I started with a Kenwood TS2000. I worked plenty of DX with it but the receive is so much on the 480. I would say spend the extra on antenna. I just looked at the 480 at AES. The difference for a new radio is 150.00 dollars. That would put 450.00 into antenna upgrade. Just my opinion.
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WX7G
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« Reply #2 on: October 11, 2012, 07:48:02 PM »

$600 will almost buy you a brand new Ameritron AL-811 ($709 at DX Engineering), 600 watt amplifier.
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W8JX
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« Reply #3 on: October 11, 2012, 08:11:24 PM »

Is it worth it to spend the extra money to purchase a 200 watt radio instead of a 100 watt radio? I think a 200 watt radio I saw was $600 more than the 100 watt version. Thanks Bill

What rigs you talking about?
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W4DBV
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« Reply #4 on: October 13, 2012, 11:30:17 AM »

That depends upon whether half an "S" unit is worth the difference in price to you. 
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VE3FMC
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« Reply #5 on: October 13, 2012, 12:09:06 PM »

$600 difference, what rig are you looking at?

In Canada I can buy the 200 watt version of the TS-480 for $100 more than the 100 watt version.

But as noted if the difference is $600 then buy a 100 watt radio and put that $600 into an amp and you will gain 500 + watts.
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AG6WT
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« Reply #6 on: October 13, 2012, 01:22:52 PM »

$600 difference, what rig are you looking at?

My guess is that Bill is looking at the FT-2000 vs FT-2000/D. The D model is the 200 watt model and costs about $600 USD more.
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W6UV
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« Reply #7 on: October 15, 2012, 12:38:23 PM »

If you're into high duty cycle modes like RTTY, then a 200 watt rig will probably let you run at 100 watts all day long, while running a 100 watt rig at 100 watts may quickly overheat.
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WX7G
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« Reply #8 on: October 15, 2012, 12:59:45 PM »

If you're into high duty cycle modes like RTTY, then a 200 watt rig will probably let you run at 100 watts all day long, while running a 100 watt rig at 100 watts may quickly overheat.

Cranking a 200 watt transmitter down to 100 watts does not decrease the power dissipated. It does cut the DC-RF efficiency.

The final amp might have a DC input power of 400 watts for 200 watts RF output and a DC input power of 300 watts for 100 watts RF output. In both cases the amplifier dissipates 200 watts.

It's easy to test this by recording the DC input power to a transceiver as the RF output power is reduced. Subtract the receive current to obtain more realistic transmit current. Then calculate the DC-RF efficiency and power dissipated.
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WB8UHZ
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« Reply #9 on: October 15, 2012, 03:53:16 PM »

  No you are only talking about 3db more in signal which is a half S-unit, the lowest amount noticeable at the receiving end to tell any difference. Save the money.
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W8JI
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« Reply #10 on: October 15, 2012, 08:21:53 PM »

I like 200W radios with AL1200 amplifiers, or 3-500Z amplifiers. 100W radios are plenty for 8877 amplifiers.

In a linear amplifier when quiescent current is small compared to operating current, efficiency decreases by the square root of power change. Half the power is sqrt .5 = .707 of original efficiency. 1/4 the power is sqrt .25 = .5 of original eff.

Let's say the input power is 400 watts for 200 watts out, 50% eff, linear stage, and negligible quiescent current.

400 input 200 output  = 200W heat =50% eff
346.4 input 150 output  =196.4 w heat = 43.3%
282.9 input 100 output =182.9W heat  = 35.35% eff
200 input 50 output = 150W heat =25% eff

Heat does not drop much in the PA with power reduction, but it does in the power supply!  1/4 the power is half the supply heat.



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K3CXG
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« Reply #11 on: October 19, 2012, 11:49:55 AM »

If I were in your shoes, I'd get the 100 watt version, and spend the extra money on a good antenna.  200 vs. 100 isn't as important as how you launch your signal.  If you're on some acreage out in Howard County, you might want to put up at least a small tower.  I'm in a subdivision in Frederick County, with restrictions, so it's stealth all the way.

73,  Mike K3CXG
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WX7G
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« Reply #12 on: October 19, 2012, 01:39:04 PM »

KB3FFH, you must ask yourself these two questions:

If I buy the 100 watt radio will I regret not going for the 200 watt version?

If I buy the 200 watt radio will I regret not going for the 100 watt version?
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W6UV
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Posts: 538




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« Reply #13 on: October 19, 2012, 11:05:49 PM »

If you're into high duty cycle modes like RTTY, then a 200 watt rig will probably let you run at 100 watts all day long, while running a 100 watt rig at 100 watts may quickly overheat.

Cranking a 200 watt transmitter down to 100 watts does not decrease the power dissipated. It does cut the DC-RF efficiency.

The final amp might have a DC input power of 400 watts for 200 watts RF output and a DC input power of 300 watts for 100 watts RF output. In both cases the amplifier dissipates 200 watts.

Sure, power dissipated as heat isn't a linear function, so reducing power output from 200 watts to 100 watts won't cut dissipated power in half, but it's not going to dissipate the same amount of power as heat as at 200 watts out either.

I know someone who ran a test with a 200 watt rig (an Icom IC-7700). He ran it at 200 watts in RTTY into a dummy load and the the rig started cutting back power at 8 minutes into the test. When he reduced output to 100 watts, it never cut back the output power. So in this particular case, running at 100 watts output was enough of a reduction that the rig never needed to cut back power.
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WX7G
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« Reply #14 on: October 20, 2012, 05:40:46 PM »

Can you test this with your radio?  From the TX current at full and 1/2 power subtract the RX current. Calculate PA dissipation and post your results for another data point.
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