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Author Topic: Choosing a Legal Limit Amp  (Read 18825 times)
W8JX
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« Reply #30 on: April 19, 2013, 07:54:57 AM »

8877's have a finite life based on cathode emissivity and it degrades over time regardless of being in standby or transmitting. Two tubes will last as long as one at legal limit. Also one tube can do 1.5kw 24/7 with ease if power supply is up to duty cycle too. You do not need two to do 24/7 but you do for 3kw and more 24/7.
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W6UV
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« Reply #31 on: April 19, 2013, 09:09:34 AM »

8877's have a finite life based on cathode emissivity and it degrades over time regardless of being in standby or transmitting. Two tubes will last as long as one at legal limit. Also one tube can do 1.5kw 24/7 with ease if power supply is up to duty cycle too. You do not need two to do 24/7 but you do for 3kw and more 24/7.

My friend has a car that develops 600 HP -- do you think that's excessive too since the speed limit here in California is 65-70 MPH?
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W8JX
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« Reply #32 on: April 19, 2013, 11:17:44 AM »

8877's have a finite life based on cathode emissivity and it degrades over time regardless of being in standby or transmitting. Two tubes will last as long as one at legal limit. Also one tube can do 1.5kw 24/7 with ease if power supply is up to duty cycle too. You do not need two to do 24/7 but you do for 3kw and more 24/7.

My friend has a car that develops 600 HP -- do you think that's excessive too since the speed limit here in California is 65-70 MPH?

Not the same. I have owned muscle cars in past too and played with them on strip but they did not perform well on street legally. The is only one reason to build/have a amp with two 8877's or three 3cx800's is because you plan to use the extra power regularly but far be it for anyone to openly admit doing it. I here a guy on 40m sometimes that is clearly running excess power and splattering all over too and get away with it but it does not make it right. Sorry if I seem a downer on this but I am "old school" and play by rules even when others do not.
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W6UV
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« Reply #33 on: April 19, 2013, 11:28:18 AM »

Quote
My friend has a car that develops 600 HP -- do you think that's excessive too since the speed limit here in California is 65-70 MPH?

Not the same. I have owned muscle cars in past too and played with them on strip but they did not perform well on street legally.

My friend's car (Ferrari 599GTO) is not a muscle car only designed to go fast in a straight line. It'll do 200+ MPH even though the speed limit around here is 65/70 MPH. This is exactly analogous to the 2x 8877 amps -- one doesn't use them to their full capabilities, but it's nice knowing that they can.
« Last Edit: April 19, 2013, 11:30:39 AM by W6UV » Logged
W8JX
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« Reply #34 on: April 19, 2013, 11:36:29 AM »

My friend's car (Ferrari 599GTO) is not a muscle car only designed to go fast in a straight line. It'll do 200+ MPH even though the speed limit around here is 65/70 MPH. This is exactly analogous to the 2x 8877 amps -- one doesn't use them to their full capabilities, but it's nice knowing that they can.

Poor excuse. They buy the twin 8877 to run them not idle them. Why else would you want a amp that wears out two $1000 tubes at same rate as a single tube amp if you do not plan to play them. 8877's wear out at same rate transmitting or idle.
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N4ATS
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« Reply #35 on: April 19, 2013, 02:48:53 PM »

I wonder back in the day,  when ham radio was being invented, if the inventors thought about a bunch of clowns in the future,  telling them their inventions were not good enough, changed their intentions?

I love my Camaro

« Last Edit: April 19, 2013, 02:59:32 PM by N4ATS » Logged
N4RSS
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Posts: 260




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« Reply #36 on: April 19, 2013, 07:10:54 PM »

My friend's car (Ferrari 599GTO) is not a muscle car only designed to go fast in a straight line. It'll do 200+ MPH even though the speed limit around here is 65/70 MPH. This is exactly analogous to the 2x 8877 amps -- one doesn't use them to their full capabilities, but it's nice knowing that they can.

Poor excuse. They buy the twin 8877 to run them not idle them. Why else would you want a amp that wears out two $1000 tubes at same rate as a single tube amp if you do not plan to play them. 8877's wear out at same rate transmitting or idle.




Talk to the hand
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W8JX
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« Reply #37 on: April 19, 2013, 07:31:16 PM »

My friend's car (Ferrari 599GTO) is not a muscle car only designed to go fast in a straight line. It'll do 200+ MPH even though the speed limit around here is 65/70 MPH. This is exactly analogous to the 2x 8877 amps -- one doesn't use them to their full capabilities, but it's nice knowing that they can.

Poor excuse. They buy the twin 8877 to run them not idle them. Why else would you want a amp that wears out two $1000 tubes at same rate as a single tube amp if you do not plan to play them. 8877's wear out at same rate transmitting or idle.




Talk to the hand

Nah, They do not buy for head room, they buy them break the limit. And ham radio used to be such a honorable "honest" hobby too. A few years ago I watched a US ham try to buy the 8kw amp Emtron had on display and it was not for headroom.
« Last Edit: April 19, 2013, 07:33:19 PM by W8JX » Logged

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N6AJR
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« Reply #38 on: April 21, 2013, 05:48:32 PM »

call alpha/ rf concepts and talk with them, they are the experts
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W8JX
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« Reply #39 on: April 21, 2013, 07:40:36 PM »

call alpha/ rf concepts and talk with them, they are the experts


And ask them about what? What the "limit" really is? They make good money of amps that will exceed legal limit easily so what do you think they are going to say?  Duh...
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KD8MJR
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« Reply #40 on: April 21, 2013, 08:14:52 PM »

I own a Tokyo hy power 1.2 Kfx and its a work of art in the interior. It's pretty hard to blow this thing up because the protection is so good. You cannot go wrong with a THP amp and the owners of the 2.5 kfx say that it's not called a 2.5kfx for nothing Wink
I can do 900 watts with my 1.2kfx and even 1kw without problems but of course your mileage may vary.
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W6UV
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« Reply #41 on: April 22, 2013, 01:16:42 PM »

Thanks for all of the comments and advice.

I bought an Alpha 8410 at the Visalia DX convention over the weekend. The show special was a free set of spare 4CX1000A tubes for the amp.
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N4CR
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Posts: 1668




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« Reply #42 on: April 22, 2013, 02:21:17 PM »

And ask them about what? What the "limit" really is? They make good money of amps that will exceed legal limit easily so what do you think they are going to say?  Duh...

I'm surprised you can still walk with a chip on your shoulder that is as big as the one you carry.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
N4ATS
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Posts: 812




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« Reply #43 on: April 22, 2013, 03:36:11 PM »

"I'm surprised you can still walk with a chip on your shoulder that is as big as the one you carry"

Common problem now-adays , it ain't like it used to be where everyone was friendly to eachother.

W6UV , you did the right thing and you will LOVE your new Alpha , it will last you for years. It will load up easy and cruize at full output, all day long.

Hope to hear you on 3.950

N4ATS
« Last Edit: April 22, 2013, 03:41:39 PM by N4ATS » Logged
W8JX
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Posts: 5877




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« Reply #44 on: April 22, 2013, 03:59:52 PM »

And ask them about what? What the "limit" really is? They make good money of amps that will exceed legal limit easily so what do you think they are going to say?  Duh...

I'm surprised you can still walk with a chip on your shoulder that is as big as the one you carry.

No chip, just old school and do not like companies that exploit loop holes for profit. Truth is though they pretty much gutted FCC enforcement in first part of last decade and commercialized Ham Radio by removing code requirement to boost sales and profits. If you have the coin you can by any amp you want for ham use it seems.   Funny thing is for years they slammed CB for running amps and yet amps that that can make "illegal" power for ham use are okay. Bizarre   
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