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eHam Forums => Amplifiers => Topic started by: W6UV on April 14, 2013, 09:49:33 PM



Title: Choosing a Legal Limit Amp
Post by: W6UV on April 14, 2013, 09:49:33 PM
I'm ready to buy a legal limit amp and have narrowed my choices down to a few. I want something closer to the high-end rather than the low end, so my list doesn't include any Ameritrons.

Prime considerations are durability and availability of tubes/transistors in the future. Here's my list, ordered by preference:

1. Alpha 8410. Alpha is a U.S. company with a very good reputation for building robust, quality products. For almost my entire ham career of 33 years, Alpha has been one of the gold standards. I see only two shortcomings with this amp -- the 4CX1000A tubes may become hard to get in the future, and the use of a microcontroller in the protection circuits may make this amp impossible to repair in the future if the microcontroller (or other components) are not available. Alpha has an excellent reputation for service and support.

2. Tokyo Hy-Power HL-2.5Kfx. SS amp that doesn't need tuning. All of my antennas have SWR < 1.5:1 where I operate, so I won't need an antenna tuner to keep this amp happy (for now). About $600 more than the Alpha 8410. Prime concerns with this amp are the availability of the ARF-1500 MOSFETS in the future and the availability of service since the company is in Japan. Another consideration is RTTY output is only 1KW with a 5 minute limit (I do RTTY contesting) -- the Alpha 8410 is brick-on-the-key 1.5KW all modes with no time limit.

3. Other tube amp, such as an Acom 1500 or Emtron DX-2SP. Concerns are with tube availability (FU-728F for the Emtron and 4CX1000A for the Acom) and support from Bulgaria or Australia.

Opinions on this list? Anything else I should consider?


Title: RE: Choosing a Legal Limit Amp
Post by: K2DC on April 15, 2013, 03:10:04 AM
The obsolescence issues you raise are true of any amplifier (or any other peice of electronic equipment), regardless of whether it's a tube or SS amp.  It's interesting that you didn't raise the microprocessor availability issue with the THP, as it has similar protection circuits.

Of your two prime candidates, I would definitely go with the Alpha.  Although bought used, I have a 78 and an 86 that have given me years of great service.  4CX1000's are readily available and reasonably priced compared to other higher power amatur amp tubes.  Given Alpha's known design and build quality and a set of spares, a new 8410 could easily outlive us all.

73,

Don, K2DC


Title: RE: Choosing a Legal Limit Amp
Post by: AD4U on April 15, 2013, 05:40:33 AM
Another option is trying to find a good used Alpha 77DX which will actually cost less than most if not all of the amps you mentioned.  Of course the 77DX is manual tune, which will (but should not) baffle some ops.  It covers 160 meters and 3-30 MHz continuous.  The HV filter cap is oil filled and should last a life time.  It will LOAF at the legal limit in ANY mode.  EIMAC 8877 tubes are still available. But then if you get an amp with a good EIMAC 8877 and if you don't abuse it, it will probably last a life time.  

It is probably the best HAM amp ever made.

Dick  AD4U


Title: RE: Choosing a Legal Limit Amp
Post by: W6GX on April 15, 2013, 04:53:59 PM
You didn't mention warm up time.  That three minutes may seem like eternity when a rare one is one the line.  Personally I prefer the 2.5 due to the no-tuning and no warm up time.  OTOH I don't do RTTY contesting so I'm not concerned with duty cycle.  For my operating style the 2.5 is a better choice.  If I were you I wouldn't want to run more than 1kw on high-duty RTTY into a trapped antenna.  The traps might be the limiting factor, not the amplifier.

Neither amps could do 6m.  That might be an important consideration if you are into VHF DX'ing.

73,
Jonathan W6GX


Title: RE: Choosing a Legal Limit Amp
Post by: K5RT on April 15, 2013, 07:04:43 PM
Check out the OM-2500A. It's definitely a high end legal limit amp


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV on April 15, 2013, 09:41:47 PM
You didn't mention warm up time.  That three minutes may seem like eternity when a rare one is one the line.  Personally I prefer the 2.5 due to the no-tuning and no warm up time.  OTOH I don't do RTTY contesting so I'm not concerned with duty cycle.  For my operating style the 2.5 is a better choice.  If I were you I wouldn't want to run more than 1kw on high-duty RTTY into a trapped antenna.  The traps might be the limiting factor, not the amplifier.

Warm-up time is not much of a consideration, since I power up everything as soon as I go into the shack and the computer takes at least three minutes to boot and load everything. I don't do any operating until the computer is ready.

I'll look into the trap issue on RTTY -- didn't think about that. Worst-case RTTY contesting duty cycle is about 80% when calling CQ and getting no answers. With the traps up in the always prevailing breeze around here, there is some cooling that they'll get. Besides, if I blow the traps, that'll give me an excuse to try a different antenna. :D


Title: RE: Choosing a Legal Limit Amp
Post by: N0PQK on April 15, 2013, 10:00:24 PM
QRO Technologies makes some rock solid tube amps. You may want to look into one.


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV on April 15, 2013, 10:47:56 PM
QRO Technologies makes some rock solid tube amps. You may want to look into one.

Hmmmm. The HF-3KDX looks pretty interesting. How would it compare with the Alpha 8410?


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS on April 16, 2013, 03:59:44 AM
Alpha all the way , there is NOTHING better. You can get a great price on an Alpha 89 right now , older amp with a new style that packs it all. Indestructible and 1.5 KW all day long.


Title: RE: Choosing a Legal Limit Amp
Post by: KH6DC on April 16, 2013, 10:00:00 PM
The obsolescence issues you raise are true of any amplifier (or any other peice of electronic equipment), regardless of whether it's a tube or SS amp.  It's interesting that you didn't raise the microprocessor availability issue with the THP, as it has similar protection circuits.

Of your two prime candidates, I would definitely go with the Alpha.  Although bought used, I have a 78 and an 86 that have given me years of great service.  4CX1000's are readily available and reasonably priced compared to other higher power amatur amp tubes.  Given Alpha's known design and build quality and a set of spares, a new 8410 could easily outlive us all.

73,

Don, K2DC


I second the Alpha or Tokyo Hy-Power.  But another one you might take a look is SPE Expert.

73,

Delwyn, KH6DC


Title: RE: Choosing a Legal Limit Amp
Post by: NO9E on April 17, 2013, 07:12:36 AM
The choice depends on criteria.

1. Cost. Lowest? Good value? The best that there is?
2. Value of automation.
3. Willingness for risk taking.
4. Needed headroom.

Lowest cost with good value would be AL-1500. Alpha 8410 would extra higher quality. ACOM 2000 and Alpha 9500 seem both highly rated automated amps. OM3500 would add extra headroom. Expert 2k-fa would provide the highest level of convenience ( 6 automatically switched and tuned antennas to 2 radios) but with uncertain (but seemingly very high) reliability and less headroom while covering legal-limit 6m.   

I chose 2k-fa.

Ignacy



Title: RE: Choosing a Legal Limit Amp
Post by: W6UV on April 17, 2013, 09:00:11 AM
As always, one has a budget for such things. In my case, the Alpha 8410 is comfortably within my budget. The Tokyo HL-2.5Kfx is stretching it to the limit, but doable. The Alpha 9500 is outside my budget, as is the Acom 2000A and OM3500.


Title: RE: Choosing a Legal Limit Amp
Post by: PA1ZP on April 17, 2013, 09:05:28 AM
Hi All of you

Why not the Acom 2000?
Acom used to build amps for Alpha.

I hear great things of this amp.

maybe in the chaep range the AL82 with 2 x 3-500

I am using a AL572B and that produces more then 2 times legal limit in the Netherlands.
I do not use it much but I put in a new set of tubes 3 yrs ago and besides a set of warn tubes I had not trouble in 6 yrs of service.

Now I only put out between 400-500 PEP watts and that is enough though my antenna system for 10-40 mtrs can cope with 5 Kw PEP.

I used to use the AL572B daily but last few years only about 2 times a week for  few hours.
It does the job I needed it to do very good.

I never use it on CW because strange enough sigs on CW are always strong enough, so I can do without the amp.
A set of 4 new 572B tubes from China costed me 140 Euro's about  $200   

73 Jos


Title: RE: Choosing a Legal Limit Amp
Post by: W6GX on April 17, 2013, 10:46:16 AM
If you are still interested in the HL-2.5kfx I want you to be aware of some new developments in regards to this amp.

- HL-2.5kfx will be replaced by HL-2500kfx.  I don't know the timing but Tom Rum (US rep. for THP) should know.  There's nothing wrong with the HL-2.5kfx other than the ARF-1500 won't do 6m.  THP felt that there's a demand for an amp. that will do 160-6m.  The HL-2500kfx uses six THP2933 PAs.  THP2933 is a custom and rugged version of the ST Micro SD2933.  You should expect a price increase on the HL-2500kfx.
- The weak dollar against the yen has hurt THP's margin in the last few years.  However the dollar has gained significant ground against the yen recently.  This means that there's a potential for a price discount for the outgoing HL-2.5kfx.  Contact Tom Rum or HRO for more details.  Dayton might be a good place to purchase either amps.
- Lastly, I typically don't buy used ham equipment.  I took exception to that rule and purchased my HL-2.5kfx used.  I knew the history of the amp. so that helped my buying decision tremendously.  The upside is that I saved $2000.  The dowside is that I don't have a factory warranty.  The amp. works like a champ (see my review of it on eham).  Used ones go for $4000 however I wouldn't buy one unless you know the amp. hasn't been abused prior.  Occasionally HRO will sell an open box HL-2.5kfx at a 10% and it comes with full factory warranty.

73,
Jonathan W6GX


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS on April 17, 2013, 11:56:05 AM
There is nothing more dreamy than a set of 3CX800A's tuned up. Get an Alpha 89


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV on April 17, 2013, 11:57:42 AM
Thanks for the info, Jonathon.

I don't do 6m, so that's not a consideration. Are the THP2933 MOSFETs used in the HL-2500kfx more rugged (able to withstand greater SWR) than the ARF-1500 in the HL-2.5kfx?


Title: RE: Choosing a Legal Limit Amp
Post by: N6AJR on April 17, 2013, 12:20:30 PM
I have had many many amps over the years. everything from sweep tube amps, to clipperton L to alpha 76a's, to ameritron 811's, 811H and als500, als600, als 1200 , IC 2-KL's tl922's and so on. The one I kept and use is an alpha 87a. full automatic operation, self tuning, autoband switch  and solid as a rock.  I got it for $5500 used, and never had a problem in 6 or 8 years I have had it.  Alpha may even have a used one or to in stock.  call alpha first and see what they have.  they are the absolute best I have ever owned.  Nice to look at too. good value for the $$$. great service.


Title: RE: Choosing a Legal Limit Amp
Post by: W6GX on April 17, 2013, 09:19:16 PM
Thanks for the info, Jonathon.

I don't do 6m, so that's not a consideration. Are the THP2933 MOSFETs used in the HL-2500kfx more rugged (able to withstand greater SWR) than the ARF-1500 in the HL-2.5kfx?

The ARF-1500 has a very high source-to-drain breakdown voltage of 500v.  The HL-2.5kfx operates at a drain voltage of 125v.  The issue is not how rugged the PA is but rather how good the protection circuitry is.  No matter how good of an operator you are you will make mistakes and cause a high SWR event.  Or you could experience an equipment failure that can also cause a high SWR event.  In solid state amps. the deciding factor is whether the protection circuitry could protect a catastrophic SWR event like a shorted antenna lead.  I know of someone who blew a pair of ARF-1500s when his antenna matching network arced and caused a short on the antenna lead at full power.  THP has made some production changes to the protection circuitry in the HL-2.5kfx and all newly produced units have the latest protection circuitry.  The PA's are always at risk with repeated high SWR events, no matter how good the protection circuitry is.  Running legal limit requires that you have a very robust system- coax, lightening arrestor, matching network, antenna switch, antenna balun, antenna traps, etc.  A blown balun or trap will cause a high SWR event.  A failed or poor quality antenna switch could cause a short on the antenna lead.  Under normal use the HL-2.5kfx could withstand a SWR of 1.8:1 without harm.  I hope this helps.

73,
Jonathan W6GX


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV on April 17, 2013, 09:52:00 PM
Running legal limit requires that you have a very robust system- coax, lightening arrestor, matching network, antenna switch, antenna balun, antenna traps, etc.

Point noted. I recently rebuilt my station from the ground up and everything is designed for the legal limit as a minimum, with most things designed for 2.5-4KW.


Title: RE: Choosing a Legal Limit Amp
Post by: NK2F on April 18, 2013, 02:11:03 AM
You may want to take a look at Alpin 200, also a Bulgarian-made amp, on the same platform as the Alphas and Acoms. The Alpin brand is unknown in the US, but it is in Europe, with raving reviews in the German and UK publications. Distributed by EU dealers, direct to the rest of the world. CE tested and listed so you know you are not buying an IMD nightmare. Pi-L circuit has the ability to match loads to 3:1 so no need for an antenna tuner. Tons of high end protection circuits so the tubes will last forever. I measured over 2400W on 15m with about 70W of drive power. Best tuning indicator I have used, making manual tune as fast as automatic.

Take a look at http://www.alpinamplifier.com/index.php?option=com_content&view=article&id=3&Itemid=10  Note that the price for the US is 20% less (no sales tax) and shipping, at least to NYC area, is around $400, delivered in less than a week with no import duties or taxes of any kind.


Title: RE: Choosing a Legal Limit Amp
Post by: N4FBW on April 18, 2013, 05:29:54 PM
Getting service for a THP amp is not a problem. AVSL services THP products, just stop by the THP website for more information.


Title: RE: Choosing a Legal Limit Amp
Post by: AD4U on April 18, 2013, 05:35:59 PM
There is nothing more dreamy than a set of 3CX800A's tuned up. Get an Alpha 89

Except possibly a pair of 8877's in an Alpha 77SX.  I know because I have one.   HI   ;)

Dick  AD4U


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX on April 18, 2013, 05:37:48 PM
There is nothing more dreamy than a set of 3CX800A's tuned up. Get an Alpha 89

Except possibly a pair of 8877's in an Alpha 77SX.  I know because I have one.   HI   ;)

Dick  AD4U

And why would you have a pair of them unless you like running well beyond legal limit.


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS on April 18, 2013, 06:14:57 PM
Simple.....Head room

Unlike most over-rated amps...

Amateur Radio...Think Simplistic


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX on April 18, 2013, 06:40:04 PM
Simple.....Head room

Unlike most over-rated amps...

Amateur Radio...Think Simplistic

Head room, not likely when a single tube can close to 3kw with proper power supply.  Run as much power as you can afford and get away with it seems


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS on April 19, 2013, 04:05:30 AM
Opposite , run as easy as you can while maintaining full legal limit.


Title: RE: Choosing a Legal Limit Amp
Post by: AD4U on April 19, 2013, 05:21:53 AM
There is nothing more dreamy than a set of 3CX800A's tuned up. Get an Alpha 89

Except possibly a pair of 8877's in an Alpha 77SX.  I know because I have one.   HI   ;)

Dick  AD4U

And why would you have a pair of them unless you like running well beyond legal limit.


Why do you drive a car that can go faster than the legal speed limit?  It is because you drive 100 MPH every where you go??  I bought the 77SX in 1991 for $2000 because the owner had to sell it and I wanted to buy it.  I have ben offered and refused $5000.  Good investment??


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS on April 19, 2013, 05:45:36 AM
"Why do you drive a car that can go faster than the legal speed limit?  It is because you drive 100 MPH every where you go??  I bought the 77SX in 1991 for $2000 because the owner had to sell it and I wanted to buy it.  I have ben offered and refused $5000.  Good investment??"

Exactly and well put. Most of the amps on the market (cheap stuff like MFJ) may say legal limit or rated at 600 watts and yes , they can reach legal limit or 600 watts , but hold that power long? Most will melt down because to reach that limit , you have to go balls to the wall.

Alpha , set it at 1.5 KW , key it on FM, walk away and come back an hour later , still 1.5K



Title: RE: Choosing a Legal Limit Amp
Post by: AD4U on April 19, 2013, 06:47:07 AM
"Why do you drive a car that can go faster than the legal speed limit?  It is because you drive 100 MPH every where you go??  I bought the 77SX in 1991 for $2000 because the owner had to sell it and I wanted to buy it.  I have ben offered and refused $5000.  Good investment??"

Exactly and well put. Most of the amps on the market (cheap stuff like MFJ) may say legal limit or rated at 600 watts and yes , they can reach legal limit or 600 watts , but hold that power long? Most will melt down because to reach that limit , you have to go balls to the wall.

Alpha , set it at 1.5 KW , key it on FM, walk away and come back an hour later , still 1.5K



Agreed..........If anybody wants to run with the BIG GUNS in HAM radio, you DO NOT do it with an Alpha 77SX, except perhaps as a driver for the big amp.


Title: RE: Choosing a Legal Limit Amp
Post by: NN4X on April 19, 2013, 07:34:28 AM
Dishtronix Prometheus DX2400: It's the modern-day equivalent of the Alpha 77DX.


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX 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.


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV 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?


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX 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.


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV 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.


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX 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.


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS 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



Title: RE: Choosing a Legal Limit Amp
Post by: N4RSS 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


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX 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.


Title: RE: Choosing a Legal Limit Amp
Post by: N6AJR on April 21, 2013, 05:48:32 PM
call alpha/ rf concepts and talk with them, they are the experts


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX 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...


Title: RE: Choosing a Legal Limit Amp
Post by: KD8MJR 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 ;)
I can do 900 watts with my 1.2kfx and even 1kw without problems but of course your mileage may vary.


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV 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.


Title: RE: Choosing a Legal Limit Amp
Post by: N4CR 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.


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS 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


Title: RE: Choosing a Legal Limit Amp
Post by: W8JX 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   


Title: RE: Choosing a Legal Limit Amp
Post by: K7KBN on April 22, 2013, 11:02:19 PM
Reminds me of a QST article from the early 60s.  Written by John Troster, W6ISQ (SK), it was a tongue-in-cheek look at "California Kilowatts".

One of the comments allegedly overheard on 75 meters was about the Collins KWS-1:  "It sure makes a dandy exciter for my amplifier!"

Another paragraph noted that a true California Kilowatt station uses silver dollars for key contacts...


Title: RE: Choosing a Legal Limit Amp
Post by: K6AER on April 23, 2013, 12:10:45 PM
The new Alpha amps don't go much over the legal limit. My 8410 would only do about 1900 watts. My buddies 9500 was about the same.

As for 8877 degradation, the tube will produce 1500 watts easily for 35 years. Key is not to exceed the grid current rating.

I would perfer to have an amplifier with at least 2-3 dB of head room. IMD will be much better with complex modulation.

Despite popular wisdom most 911 turbos just follow the car in front of them.


Title: RE: Choosing a Legal Limit Amp
Post by: N4ATS on April 23, 2013, 02:22:17 PM
Despite popular wisdom most 911 turbos just follow the car in front of them.

Soooo true

Bill


Title: RE: Choosing a Legal Limit Amp
Post by: W5ZL on April 26, 2013, 01:28:32 PM
Currently, I have 4 amplifiers.  The AL-811, a Heathkit SB-220 a converted SB-221 to 6M and an Alpha-9500 with an Alpha-4510 Power/SWR Meter which I have had for the past year and a half.  Before Alpha-9500, I had an Alpha-87A for about 3 years.  At this point, I have to force myself to use one of my other amps, otherwise, I would never turn on anything except the Alpha-9500; it is a sweet machine to operate.  The Alpha-9500 couldn't be easier to operate.  All you have to do is select the band on your Exciter, reduce power to about 15 watts out of the exciter, press the "Auto" button on the Alpha-9500, send a continuous wave signal from the exciter, bring up the exciter power to about 42 watts and you will be at 1500 watts PEP when you switch to SSB.  Turn off the "Auto" feature of the Alpha-9500 and begin to call CQ.  I know of some operators that tune/load their systems using the Alpha-9500 without starting out with low power, they set their exciter to about 45 - 50 watts and start talking SSB and let the firmware tune the Alpha-9500; personally, I don't see any reason to stress a piece of equipment just because it will take it.  I don't think you can find a better automatic tuning RF amplifier for the money anyplace.  It is my opinion that the Alpha-9500 is a lot sweeter tuning amplifier than the Alpha-87A; but, that is just one Old Man's opinion.

Good luck with the decision on the amplifer you finally decide to acquire.


Title: RE: Choosing a Legal Limit Amp
Post by: VK2ANS on May 01, 2013, 06:02:14 PM
Hi Guys, re the new THP HL-2500FX model; I last visited the THP factory last October and saw they had delegated mostly one engineer for each new amplifier model's development, with five or six amplifiers being under development. THP's best RF engineer, "the RF genius", is developing their new HL-2500FX. THP chose to change over to THP2933s because using six of them should (in their opinion and experience) prove to be much more rugged and reliable than continuing to use two ARF-1500s. The added bonus is the new HL-2500FX amplifier would also operate up on 6m, unlike the HL-2.5KFX. This new amplifier should be available soon, but I haven't checked with THP for a few months in this regard.
Lee. VK2ANS.   


Title: RE: Choosing a Legal Limit Amp
Post by: KC4MOP on May 03, 2013, 07:47:14 AM
I am thinking that the rage for MORE QRO is that there seems to be a lot more inconsiderate operators on the air now. The ops "playing the game" have to deal with tuner-uppers and ops who like to "Hold the Frequency". Complete silence until you ask if the frequency is in use and then they start to chatter. Or 250khz of band space and QSO's are happening within a 1kc of each other. It takes about 3-4 khz spacing for SSB, and 6khz, for an AM QSO. But no, you hear an AM QSO and there's SSB ops trying their damndest to talk over the AM QSO, either on freq or within 1 khz of the AM QSO.
I know it's a losing battle that whomever can put out the largest signal and be the channel master is the one who wins. Seems like a CB mentality.
Legal QRO, and make improve the antenna.


Title: RE: Choosing a Legal Limit Amp
Post by: AD9DX on May 06, 2013, 08:33:31 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.

I am sure you are loving it. I have an Alpha 76a that I sent to Dick Byrd to have it converted to use a pair of 3cpx800a7 tubes and a QSK relay. My previous amp was a Heathkit SB-200 and I couldn't be happier. Unless I can some day find a Alpha 87a or 9500 for cheap, it is the last amp I will e er have to buy.

I am sure that your 8410 will suit you the same way.


Title: RE: Choosing a Legal Limit Amp
Post by: KA7NIQ on May 19, 2013, 07:41:33 PM
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.
Thanks for saying, what needed to be said!
Too many Hams these days are running FAR in excess of Legal Power, and to make things even worse, these LIDS are widening their transmit bandwidths, all in the name of so called "Hi Fi Audio" (ESSB), and splattering away.




Title: RE: Choosing a Legal Limit Amp
Post by: KA7NIQ on May 19, 2013, 07:54:32 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   
Yeah, they blasted CB'ers for Roger Beeps and Echo Boxes, yet some of these ESSB Lids  are using a "touch of reverb" with bandwidth so wide, they occupy BOTH sidebands!
It has gotten so bad on 75 meters here in Florida, that power outputs far in excess of legal power are openly talked about.
Though these LIDS are already S9+ with 100 watts, they will run far in excess of legal power, even when conditions do not warrant it.
Speak your mind W8JX, I hear you, loud and clear!



Title: RE: Choosing a Legal Limit Amp
Post by: ZENKI on May 20, 2013, 04:42:56 AM
Nobody mentions how important  the issue of spectral cleanliness of amplifiers. Tubes and solid state amplifiers with poor IMD performance should really be placed at the bottom of your list.

You cant rely on the ARRL reviews to tell  you how clean the amp is. The ARRL simply ignores the issues and does not care if the AMP Is dirty. Every piece of crap spewing out IMD garbage is OK by them if they review it.
 An example is  the review of the Acom 1500 amp in this months QST. -27db 3rd order  and -49db 9th order. Rather unspectacular figures yet they say nothing about such amplifiers. A 8877 as comparison has superior IMD performance. The current batch of solid state amplifiers are also rather poor performers but the ARRL just keeps on reviewing like everything is well. Hear no evil see no Evil!

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.






Title: RE: Choosing a Legal Limit Amp
Post by: AD9DX on May 20, 2013, 05:40:21 AM
Nobody mentions how important  the issue of spectral cleanliness of amplifiers. Tubes and solid state amplifiers with poor IMD performance should really be placed at the bottom of your list.

You cant rely on the ARRL reviews to tell  you how clean the amp is. The ARRL simply ignores the issues and does not care if the AMP Is dirty. Every piece of crap spewing out IMD garbage is OK by them if they review it.
 An example is  the review of the Acom 1500 amp in this months QST. -27db 3rd order  and -49db 9th order. Rather unspectacular figures yet they say nothing about such amplifiers. A 8877 as comparison has superior IMD performance. The current batch of solid state amplifiers are also rather poor performers but the ARRL just keeps on reviewing like everything is well. Hear no evil see no Evil!

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.






My god this is the same topic you have posted in at least two different threads this morning. Why not try writing a letter to your senator.  The amps discussed meet or exceed FCC requirements. If you want companies to do better, petition the FCC to change their standards. 


Title: RE: Choosing a Legal Limit Amp
Post by: W5JON on May 20, 2013, 06:17:53 AM
Nobody mentions how important  the issue of spectral cleanliness of amplifiers. Tubes and solid state amplifiers with poor IMD performance should really be placed at the bottom of your list.

You cant rely on the ARRL reviews to tell  you how clean the amp is. The ARRL simply ignores the issues and does not care if the AMP Is dirty. Every piece of crap spewing out IMD garbage is OK by them if they review it.
 An example is  the review of the Acom 1500 amp in this months QST. -27db 3rd order  and -49db 9th order. Rather unspectacular figures yet they say nothing about such amplifiers. A 8877 as comparison has superior IMD performance. The current batch of solid state amplifiers are also rather poor performers but the ARRL just keeps on reviewing like everything is well. Hear no evil see no Evil!

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.






My god this is the same topic you have posted in at least two different threads this morning. Why not try writing a letter to your senator.  The amps discussed meet or exceed FCC requirements. If you want companies to do better, petition the FCC to change their standards. 


AD9DX,
Thank you , thank you, I also have become very tired of Mr. (I have no callsign), (one tune) Zenki.  To him IMD is the ONLY thing that matters, and his one man campaign of criticizing almost every amplifier made today for IMD is getting real old. Zenki, you have made your point HUNDREDS of times, give it a rest. 

John  W5JON  -  V47JA 


Title: RE: Choosing a Legal Limit Amp
Post by: W6UV on May 20, 2013, 08:03:21 AM
If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.

Zenki,

Your comments would carry a lot more weight if you posted your call sign (as you claim to have) rather than hiding behind an anonymous screen name. If nearly everyone else on eHam posts using their call sign, why can't you? What do you have to hide?


Title: RE: Choosing a Legal Limit Amp
Post by: K5RT on May 21, 2013, 04:25:26 AM
I'm wondering if Zenki might be WB2WIK. To me, his words (not to mention this subject), sure sound like Steve talking.


Title: RE: Choosing a Legal Limit Amp
Post by: K6AER on May 21, 2013, 02:42:47 PM
Trust me Steve is not Zinke. Steve is proud of his call and has been a ham for too long to go chasing windmills.


Title: RE: Choosing a Legal Limit Amp
Post by: KA7NIQ on May 21, 2013, 02:57:16 PM
Trust me Steve is not Zinke. Steve is proud of his call and has been a ham for too long to go chasing windmills.
I totally agree!
Besides, I know Steve as much more of an
Antenna Elmer type, then an Amplifier IMD type of guy.


Title: RE: Choosing a Legal Limit Amp
Post by: W5JON on May 21, 2013, 04:45:18 PM
Trust me Steve is not Zinke. Steve is proud of his call and has been a ham for too long to go chasing windmills.
I totally agree!
Besides, I know Steve as much more of an Antenna Elmer type, then an Amplifier IMD type of guy.


I have known Steve, WB2WIK for 45 years, and I can assure you he is not Zenki.  However I have read that Zenki is N2NEP. 

However that being said, AD9DX is exactly correct when he wrote to "Mr. NO CALLSIGN Zenki : "The amps discussed meet or exceed FCC requirements. If you want companies to do better, petition the FCC to change their standards".  Zenki has beaten his multi- year one man IMD campaign to death.

73,

John



Title: RE: Choosing a Legal Limit Amp
Post by: W6UV on May 21, 2013, 05:48:09 PM

However I have read that Zenki is N2NEP. 

Nah, Zenki is really Kurt N Sterba's evil twin.


Title: RE: Choosing a Legal Limit Amp
Post by: ZENKI on May 23, 2013, 01:42:41 AM
IMD is not the only issue, but hey the impact of any  amplifier with bad IMD performance affects all ham operators. Do you want the ham bands to sound like the CB band thats full of splatter?

The importance of the IMD issue is also this. There is little point in buying a state of the art transceiver with high performance when a bad IMD amplifier makes performance numbers largely irrelevant. Do  hams actually understand this
point or are we just brain dead CB operators who cant understand this simple point.

While I might be  ranting and raving continuously on this issue, its a point in radio physics thats important  for maintaining  the excellent weak signal performance of the ham bands. Look at the ham bands in suburban areas
its almost  a  waste of time using HF in many suburban locations because of noise pollution. What leg do hams have to stand on when they cant even keep their own act clean? So we going to turn the bands into splattered filled bands full of IMD and splatter from poor amplifiers such as CB amplifiers  that cause excessive  splatter.  We have a duty of care to pass on  to the next generation of hams a set of standards that  define how we enjoyed the ham bands in the past, operating on bands free of QRM caused from operators and other man made sources..

Anyhow hams who argue against IMD performance I am sorry to say are dummies and simply dont get  it.. They rush out bragging about their wonderful transceivers with sky high receiver numbers and cant even understand
that these radios are useless unless transmitters are clean. Its even more importance on the VHF bands. But hey   I can understand when people dont have the brains to understand a simple issue like IMD and splatter and carry  on like dumb CB'ers with all knobs to the right splattering everyone with  bad equipment choices. A not very ham friendly spirit that preserves the excellent resource called the HF bands in a pristine condition free of crud. Hams who cause excessive  splatter due to poor operating practices and  poor equipment choices are no better than a dumb CB'er who gives no thought to what they are doing nor care too understand the impact of what they doing.

So  you can throw all the mud in my direction, I dont mind. At the end of the its only  you who looks bad because you so ignorantly  dont fully  understand  the importance of the issue. There are a great  number of hams who have technical expertise who understand this issue and say nothing. Its only the loud mouth know nothings who make the same old lame attacks about no callsign or other trivial  rubbish. Why dont  you address the issue of IMD and  show us your genius and explain why amplifiers with poor IMD  has no impact on hams and the ham bands. I would be interested in your arguments.  I am sure so would many hams would also be interested in another view rather prattling on about nothing. Nobody else can produce a counter argument as to why a crap IMD CB amplifier  or any crap amplifier for that matter is good for the ham bands. The floor is yours SIR! 

When the ITU considers these standards necessary for professional HF users, I cant take comfort that I am on the right side of the argument. How confident are you in your argument against the best possible IMD standards?


Nobody mentions how important  the issue of spectral cleanliness of amplifiers. Tubes and solid state amplifiers with poor IMD performance should really be placed at the bottom of your list.

You cant rely on the ARRL reviews to tell  you how clean the amp is. The ARRL simply ignores the issues and does not care if the AMP Is dirty. Every piece of crap spewing out IMD garbage is OK by them if they review it.
 An example is  the review of the Acom 1500 amp in this months QST. -27db 3rd order  and -49db 9th order. Rather unspectacular figures yet they say nothing about such amplifiers. A 8877 as comparison has superior IMD performance. The current batch of solid state amplifiers are also rather poor performers but the ARRL just keeps on reviewing like everything is well. Hear no evil see no Evil!

If I was shopping for a decent tube or solid state amp I would by the model that produces the cleanest signal. Clean means no tetrode amplifiers, poorly designed solid state and CB amplifiers. Manufacturers like Tokyo High Power and other are stuffing industrial RF fets into their amplifier designs. These FETS are not linear RF devices meant for linear SSB service. The outcome is a dirty amplifier designs  that have poor IMD performance that is  no better than a crap CB amplifier.






My god this is the same topic you have posted in at least two different threads this morning. Why not try writing a letter to your senator.  The amps discussed meet or exceed FCC requirements. If you want companies to do better, petition the FCC to change their standards. 


AD9DX,
Thank you , thank you, I also have become very tired of Mr. (I have no callsign), (one tune) Zenki.  To him IMD is the ONLY thing that matters, and his one man campaign of criticizing almost every amplifier made today for IMD is getting real old. Zenki, you have made your point HUNDREDS of times, give it a rest. 

John  W5JON  -  V47JA 
[/quote]


Title: RE: Choosing a Legal Limit Amp
Post by: W5JON on May 23, 2013, 08:42:03 AM
Zenki,

The point that I, and others have tried to make, and one that you continuously choose to ignor is, PETITION THE FCC.

For years you have been on this anonymous rant on IMD, but have chosen to not to PETITION THE FCC, to change the IMD standard.  When an amp discussed on Eham meets or exceeds FCC requirements. If you want companies to do better, PETITION THE FCC to change their standards, to meet what YOU perceive a "acceptable".

On almost every amplifier topic, here comes Zenki with a comment, on how this, or that amplifier does not meet YOUR IMD requirements.  You have made your point HUNDREDS of times. We get the message, IMD is bad, and only you realize that, so PETITION THE FCC to change their standards. That is how a "Standards" CHANGE WORKS, not years of ranting on Eham.

Sorry, but I just realized, the FCC does not accept anonymous petitions.
......
John W5JON