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Author Topic: Why can't HF amps above the legal limit made in USA be sold legally in USA  (Read 31420 times)
K6AER
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Posts: 5726




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« Reply #15 on: November 20, 2016, 09:51:28 AM »

Actually the Alpha 8410 now uses a pair of 4CX1500B's but that is because they get the tubes cheaper in bulk. The 8410 is still power supply limited to about 2 KW out.

It is interesting on the OM-2000+ the tetrode FU728F has a lot of gain. At 1800 watts out my amplifier needs only 26 watts of drive for about 18.3 dB of gain. At 1500 watts out the drive is at 19 watts for about 19 dB of gain.

Having an amplifier with lots of head room greatly helps the IMD numbers. At 1500 watts I tested the amplifier at 39, 44, 49 dB at the 3rd, 5th and 7th from the two tone signal source. A pair of IC-7300's were combined through a 90 degree hybrid with 6 dB pads on each feed for isolation.
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N4UE
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« Reply #16 on: November 20, 2016, 10:23:55 AM »

Go to the "XFORCE" website and check out the '48 pill' model.
Love to see the spectrum plot of that thing..... ha ha

ron
N4UE
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If you're not the lead sled dog, the view never changes......
ONAIR
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Posts: 3735




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« Reply #17 on: November 20, 2016, 03:18:02 PM »

There is a whole underground of CB " box builders"  throughout the US.  They build amps that dwarf anything available to hams.  I'm talking major triodes and tetrodes with handles.  Many which require a separate 200 amp service just for the amplifier.  The serious boxes start at 5kw and go up.  Cascading solid state devices in numbers of small travel size pain relief bottles, if you know what I mean.  A simple YouTube search

Its just crazy isn't it.  There are some real monsters going around on youtube, and the guys that build them seem to be lacking basic technical knowledge.

Somehow or another, they've learnt what to solder together to make things work, and then push poor tubes and transistors to within an inch of their life. 

Aside from the terrible in band distortion products (the out of band products can be cleaned up with a mere TVI filter, but I bet they don't bother with that), I'd hate to think about how much money they must burn through with replacement finals.

I often wonder if the amps even really make the claimed outputs - after all, it wouldn't be too hard to change the label on a bird slug... Which would explain the popularity of bird meters among the builders of those boxes...


   Some will make even MORE than their claimed outputs!  "Dave" will make an amp for about as much power as a CBer could ever possibly want!!   www.DaveMade.mobi/
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KM4AH
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Posts: 955




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« Reply #18 on: November 20, 2016, 03:42:01 PM »

Quote
The 8410 is still power supply limited to about 2 KW out.

They will do quite a bit more than that.
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NN2X
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Posts: 338




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« Reply #19 on: November 20, 2016, 05:59:15 PM »

The Amplifier that one could buy a few years ago, is the Aussie Amp, DX3SP  (Pair of 4CX 1500, well the Chinese version FU-728F...That has the HV in the supply to support 5KW...Desk top...

Today this company has been sold to a USA company called Dishtronix-

I own a Emtron Amplifier, (DX3SP), make no mistake about it, the best AMP, you can buy today...Dollar per watt, 4 year warranty, modular section, easy to trouble shooting...(I had owned QRO 2500 DX, Kenwood AMP, SB220, and a host of others)

 
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W4KVW
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Posts: 0




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« Reply #20 on: November 20, 2016, 08:24:58 PM »

There is a whole underground of CB " box builders"  throughout the US.  They build amps that dwarf anything available to hams.  I'm talking major triodes and tetrodes with handles.  Many which require a separate 200 amp service just for the amplifier.  The serious boxes start at 5kw and go up.  Cascading solid state devices in numbers of small travel size pain relief bottles, if you know what I mean.  A simple YouTube search

UNDERGROUND? They advertise all over the World Wide Web so they are far from Underground.They advertise some that exceed 50,000 watts but most are from 2500 to 10,000 watts & they have phone numbers & addresses listed for contact information as well as PayPal info for payment.The FCC does not care nor do they have the man power to do anything that would put even a small dent in that market because it has been unregulated for so long that 99% of the operators are running illegal power there & with poor band conditions they keep building them bigger & bigger thinking they can creat their own conditions.

Clayton
W4KVW
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VK3BL
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Posts: 1789


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« Reply #21 on: November 20, 2016, 10:44:04 PM »

Its more of a matter that no one is producing new designs in the USA using the current popular tetrode - the FU-728F.

Once you figure in costs of quality control for imported Chinese tetrodes, I'm not surprised that many makers continue to use the good old triodes which only cost a little more. (These triodes are also made in China today.)

The EU manufacturers that make FU-728F amps, just moved to Chinese tetrodes once the ex-Russian tetrode stock became sparse.

My point was more that tetrodes with their higher stage gain are in some ways better suited to the task of QRO++.
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
N3QE
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Posts: 5587




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« Reply #22 on: November 21, 2016, 06:17:25 AM »

Its more of a matter that no one is producing new designs in the USA using the current popular tetrode - the FU-728F.

Once you figure in costs of quality control for imported Chinese tetrodes, I'm not surprised that many makers continue to use the good old triodes which only cost a little more. (These triodes are also made in China today.)

The EU manufacturers that make FU-728F amps, just moved to Chinese tetrodes once the ex-Russian tetrode stock became sparse.

My point was more that tetrodes with their higher stage gain are in some ways better suited to the task of QRO++.

It depends on how much "++" you want to be. 8877 based amps will develop 2.5kW just fine when driven with 100W which always seemed like a good match to me.

Certainly the west coast handbooks liked to show grid-driven tetrode amps that would take you from milliwatts to California Kilowatts.

The 3CX3000A7 owner might "want" a 400W exciter to get the full rated 7kW out, I will give you that!

Tim.
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W8JX
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Posts: 13268




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« Reply #23 on: November 21, 2016, 06:55:00 AM »

Many single-8877 amps can do 2.5KW out no problem.

This is pretty much true but few seem to understand that this is only about a 2db gain over 1500 watts and not worth the effort unless you have a ego issue like my amp is bigger than yours or they think 2db will make a difference when it will not 99% of the time. To many it is just a numbers game....
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Ham since 1969....  Old School 20wpm REAL Extra Class..
N3QE
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Posts: 5587




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« Reply #24 on: November 21, 2016, 07:19:19 AM »

Many single-8877 amps can do 2.5KW out no problem.

This is pretty much true but few seem to understand that this is only about a 2db gain over 1500 watts and not worth the effort unless you have a ego issue like my amp is bigger than yours or they think 2db will make a difference when it will not 99% of the time. To many it is just a numbers game....

I don't think it's a numbers game. The 8877 amp manufacturers certainly don't tout this ability in the ratings, in fact they do a very good job with being modest about it (perhaps just tradition back to the days when they did worry the FCC would shut manufacturing down).

Contrast that with every other amplifier out there (including OM Power's ratings, as well as solid state ratings) where they are running up the claimed power numbers as much as they can.

I think it's nice to have some reserve capacity. I know that when the meters on my amp go FULL SCALE that I goofed and left the exciter at 100W!
« Last Edit: November 21, 2016, 07:24:03 AM by N3QE » Logged
W8JX
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Posts: 13268




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« Reply #25 on: November 21, 2016, 07:24:44 AM »


I don't think it's a numbers game. The 8877 amp manufacturers certainly don't tout this ability in the ratings. Contrast that with every other amplifier out there (including OM Power's ratings, as well as solid state ratings) where they are running up the claimed power numbers as much as they can.

I think it's nice to have some reserve capacity. I know that when the meters on my amp go FULL SCALE that I goofed and left the exciter at 100W!

No its a number game for sales make no mistake. Some might use guise of "head room" but a pair of 3-500z's can do 1.5kw pretty easy and for a lot less cost and last just as long or longer but they would not have the "head room" for sales hype as few amps use high enough plate voltage to properly exploit a pair of 3-500's. A 8877 is a good tube but it is getting too pricey.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KM4AH
Member

Posts: 955




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« Reply #26 on: November 21, 2016, 09:47:15 AM »


I don't think it's a numbers game. The 8877 amp manufacturers certainly don't tout this ability in the ratings. Contrast that with every other amplifier out there (including OM Power's ratings, as well as solid state ratings) where they are running up the claimed power numbers as much as they can.

I think it's nice to have some reserve capacity. I know that when the meters on my amp go FULL SCALE that I goofed and left the exciter at 100W!

No its a number game for sales make no mistake. Some might use guise of "head room" but a pair of 3-500z's can do 1.5kw pretty easy and for a lot less cost and last just as long or longer but they would not have the "head room" for sales hype as few amps use high enough plate voltage to properly exploit a pair of 3-500's. A 8877 is a good tube but it is getting too pricey.


I think the AL-82 is the only pair of 3-500's that will actually do 1500 watts. QRO might have , but I think he is quit.
I can't think of any other that had the power supply to do it. More like 1200-1300 .
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W8JX
Member

Posts: 13268




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« Reply #27 on: November 21, 2016, 10:52:21 AM »


I don't think it's a numbers game. The 8877 amp manufacturers certainly don't tout this ability in the ratings. Contrast that with every other amplifier out there (including OM Power's ratings, as well as solid state ratings) where they are running up the claimed power numbers as much as they can.

I think it's nice to have some reserve capacity. I know that when the meters on my amp go FULL SCALE that I goofed and left the exciter at 100W!

No its a number game for sales make no mistake. Some might use guise of "head room" but a pair of 3-500z's can do 1.5kw pretty easy and for a lot less cost and last just as long or longer but they would not have the "head room" for sales hype as few amps use high enough plate voltage to properly exploit a pair of 3-500's. A 8877 is a good tube but it is getting too pricey.


I think the AL-82 is the only pair of 3-500's that will actually do 1500 watts. QRO might have , but I think he is quit.
I can't think of any other that had the power supply to do it. More like 1200-1300 .

I agree. The AL82 is arguable one of the best amps of its type out there still in production. It has a decent power supply and a higher plate voltage than other amps which increases output a bit with same drive and it also uses OEM spec cooling on tubes.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KM1H
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Posts: 5281




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« Reply #28 on: November 21, 2016, 10:58:36 AM »

Quote
It is interesting on the OM-2000+ the tetrode FU728F has a lot of gain. At 1800 watts out my amplifier needs only 26 watts of drive for about 18.3 dB of gain. At 1500 watts out the drive is at 19 watts for about 19 dB of gain.

Is the FCC's stage gain rule still in effect? It killed the NCL-2000 and other tetrode amps and led to GG triodes taking over.


Quote
I think the AL-82 is the only pair of 3-500's that will actually do 1500 watts. QRO might have , but I think he is quit.
I can't think of any other that had the power supply to do it. More like 1200-1300 .

The Viewstar 2500A which became the B&W PT-2500A easily did 1800W with 2X  3-500s and the AMp Supply LK-500 series used 3 and a no tune version was available; with 200W drive those 3 tubes would be up and puffing bright red on voice peaks.

Some of the Henry amps would do 1500 or more.
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W8JX
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Posts: 13268




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« Reply #29 on: November 21, 2016, 11:29:31 AM »

Some of the Henry amps would do 1500 or more.

I had a chance to buy a Henry (a 4k I believe) 25 years ago for 900 bucks. I passed it up because it almost sounded like a vacuum sweeper when running because of fans. I saw it do 3300+ watts into a dummy load with blowing a gasket doing it. I wished I had bought it and sat on it. It would have fetched a tidy profit today.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
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