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Author Topic: RM HLA 300 V Plus hf amplifier  (Read 26325 times)
K6AER
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Posts: 3499




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« Reply #15 on: March 13, 2012, 11:40:01 AM »

The ITU-R is an advisory body and is not binding in any legal sense. Each country has special circumstances. We have 2 million CB sets looking for a amplifier to mate with.

It does not matter what the mode the amplifier is operated in, it will still have to meet harmonic specs of TIA-603C USA (Commercial) if it has gain above 21.45 MHz. That is out to the tenth harmonic.

The FCC is concerned about out of band emissions. In band you can splatter all you want. The adjustment of the amplifier input is not a function of the device but of the person using the device. Most hams would fry the grids if there was not a grid trip on modern amplifiers. Modern amplifiers are hard enough to build and maintain a profit given most hams have no idea how to connect a linear and tune it properly. This is why new amps have so much fault monitoring.

Amplifiers are not considered emitters and do not come under the same technicals as transmitters.

The only part the FCC got wrong on amplifier requirements is the overly stringent case emissions requirements of -70 dBc (1 KW) being the same as the harmonics. As soon as you connect a amplifier to a local antenna your case emissions will only be down 10-20 dBc. This is what happens when you hand over a technical specification to a lawyer.

Also the FCC requires no gain in the 26-28 MHz region for any amplifier. I believe Europe does not have that requirement.
« Last Edit: March 13, 2012, 12:02:01 PM by K6AER » Logged
M0HCN
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Posts: 473




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« Reply #16 on: March 15, 2012, 11:53:16 AM »

That case emission requirement must be a bear to meet, box within a box anyone?

EU does not have any requirement not to provide gain at 11m, and most EU solid state amps will quite happily do so, particularly if they cover 10m, to do otherwise requires extra circuity (or code) for no benefit in the European market.  I suspect that many valve amps over here  have enough tuning range to get there on a nominally 10m setting as well.

The high power SSB on 11m is a US phenomenon as far as I can tell, it probably helps that EU CBs are FM only, so even where people are using amplifiers the opportunities for splatter are less as there is no envelope modulation.

73 Dan.
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G3RZP
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Posts: 4464




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« Reply #17 on: March 16, 2012, 01:43:26 AM »

Although ITU-R Recommendations are just that, by a very tortuous route through the Radio Regulations, SM329 applies. The Radio Regulations are international law - the Head of Delegation of the US delegation to a WRC is usually of Ambassador status. Even so, they get sent ecponomy class across the pond!
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ZENKI
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Posts: 916




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« Reply #18 on: March 16, 2012, 06:53:06 AM »

Regardless crudding the band up with a cheap CB amplifier is not the right thing to be doing on the hams bands. Increasing the noise floor of the ham bands just to accommodate cheap CB amplifiers  and new operators  budgets  is not smart. Whats going to be next, are we going to allow Class C amplifiers to be  used on SSB just because new operators cant afford a decent clean legal amplifier. We just opening a can of worms  by even discussing using these crap amplifiers on the ham bands. Why are we giving in  promoting the worst possible standards for the ham bands by using such equipment as the RM Italy amplifiers, is Dave Made and FAt Boy amplifiers the next kid off the block for new hams?


The ITU-R is an advisory body and is not binding in any legal sense. Each country has special circumstances. We have 2 million CB sets looking for a amplifier to mate with.

It does not matter what the mode the amplifier is operated in, it will still have to meet harmonic specs of TIA-603C USA (Commercial) if it has gain above 21.45 MHz. That is out to the tenth harmonic.

The FCC is concerned about out of band emissions. In band you can splatter all you want. The adjustment of the amplifier input is not a function of the device but of the person using the device. Most hams would fry the grids if there was not a grid trip on modern amplifiers. Modern amplifiers are hard enough to build and maintain a profit given most hams have no idea how to connect a linear and tune it properly. This is why new amps have so much fault monitoring.

Amplifiers are not considered emitters and do not come under the same technicals as transmitters.

The only part the FCC got wrong on amplifier requirements is the overly stringent case emissions requirements of -70 dBc (1 KW) being the same as the harmonics. As soon as you connect a amplifier to a local antenna your case emissions will only be down 10-20 dBc. This is what happens when you hand over a technical specification to a lawyer.

Also the FCC requires no gain in the 26-28 MHz region for any amplifier. I believe Europe does not have that requirement.
« Last Edit: March 23, 2012, 02:18:28 AM by ZENKI » Logged
ZENKI
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Posts: 916




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« Reply #19 on: March 16, 2012, 06:58:00 AM »

On a related note, anyone can now download the ITU standards such as SM329 without registering or paying now. Maybe if more hams actually  read SM329 they would not be so reluctant about mandatory IMD standards.

We want to fight things like BPL and we dont have the common sense to see that the  widespread use of poor IMD CB amplifiers could make the same mess of the bands, some hams just dont get it!


Although ITU-R Recommendations are just that, by a very tortuous route through the Radio Regulations, SM329 applies. The Radio Regulations are international law - the Head of Delegation of the US delegation to a WRC is usually of Ambassador status. Even so, they get sent ecponomy class across the pond!
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K6AER
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Posts: 3499




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« Reply #20 on: March 16, 2012, 12:28:34 PM »

The largest problem, “crudding the band”, are not reworked CB amplifiers. Half the hams on the air would not know where to start in connecting an amplifier.

Your on the air crud comes from;

•   To much mic. compression.

•   To high a mic. gain.

•   Over emphases low end audio response.

•   Excessive wide SSB transmissions.  (3KHz is plenty)

•   Overdriving the amplifier and expecting the ALC to remove the distortion.

•   Trying to get the last 5% out of the amplifier output.

•   Loading a 50 ohm amplifier output into ladder line.

•   RF into the audio because your G5RV is just above you in the attic.

•   Leaky coax connection (bad connectors) which were not a problem at 100 watts but now are at 1KW.

I will bet you dollars to donuts there are 10 more I forgot.
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KW6LA
Member

Posts: 91




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« Reply #21 on: March 16, 2012, 04:04:23 PM »

< < CB amplifiers could make the same mess of the bands, some hams just dont get it! > >

ZENKI…………………………………… I just don’t get it ?? I have been a Ham way to long and can’t tell you the last time I chase down someone using a dirty CB Amp on HF.

As Mike posted the top ten reasons above………. I have to listen to every time I get on the air ! Can you start Bashing those guys a little more and worry less about a guy
using a RM Italy to power up ones QRP/ CW Rig. I didn’t see a CB Amp on Mike’s list, so I don’t think he is going Atomic over this being a major problem on the air. Sure
some might be running dirty, but don’t stand on my foot ! Let see how many other Hams have had continuous trouble with CB Amps on HF ?
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G3RZP
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Posts: 4464




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« Reply #22 on: March 17, 2012, 04:48:06 AM »

There is a problem with ITU-R Rec SM.329 applied to amateur service equipment at UHF and above. If you ran CW for EME at 10 GHz and 500 watts, the way SM.329 is written you would have an impossible job to meet it because of phase noise - or of measuring it if you did.

The European interpetation of SM.329 is ERC-REC 74-01, and it takes phase noise into account in setting the levels.
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V47JA
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Posts: 104




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« Reply #23 on: March 17, 2012, 05:49:44 AM »

Hi,

1.  Mike is absolutely right on with his list.
2.  I am surprised it took ZENKI four days to post one of his name calling rants against RM Italy.

73,

John
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K1ZJH
Member

Posts: 949




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« Reply #24 on: March 17, 2012, 07:34:25 AM »

The largest problem, “crudding the band”, are not reworked CB amplifiers. Half the hams on the air would not know where to start in connecting an amplifier.

Your on the air crud comes from;

• I will bet you dollars to donuts there are 10 more I forgot.


11: Improper tuning and load setting.

Unfortunately, you are right. Many of the crudiest signals are from stations with higher end equipment.
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M0HCN
Member

Posts: 473




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« Reply #25 on: March 17, 2012, 09:43:17 AM »

Yep amplifiers are largely an irrelevance as long as we are leaving so much of the transmit chain under manual control.

It is not actually that hard to design an audio frequency limiter working in the analytic domain that will successfully limit the peak envelope of the resulting SSB signal (Note that a limiter working in real as opposed to analytic space will NOT do the right thing), without requiring any ALC feedback loop at all, particularly in a world increasing using DSP in the transmit path. The SSB envelope is bounded by sqrt (I^2 + Q^2), not by |I|.

Once you have a band limited signal that is limited so as not to cause overload on envelope peaks when converted to SSB, then adding a front end audio AGC/Compressor/Gate arrangement is not really rocket science, and you can if you must, expose those controls to the user without any risk that they will be able to cause out of channel problems.

It is only ham gear that provides the controls to allow AKTTR to cause interference, everyone else, even if they provide the knobs, includes circuitry to keep the user from screwing up adjacent channels.   

An additional refinement would be to measure |I|, |V| at the output of the PA then |Z| could be trivially calculated which could be used by the baseband DSP to throttle the drive power so that operation into 1.5:1 or worse would still be clean.

None of this is rocket science, and some of it is merely trivial software changes to any rig using DSP based phasing or weaver method SSB generation, yet removing the ability to have screwing up with the audio controls cause problems other then your own intelligibility would be a huge win. 

Amplifier IMD is actually a second tier problem compared to exciter IMD especially exciters that fall to bits when operated by the technically ignorant.

Regards, Dan.
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WB2WIK
Member

Posts: 20565




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« Reply #26 on: March 22, 2012, 09:05:31 AM »

I've been corresponding with the FCC about external amplifiers and received this message regarding external amplifiers that are market for sale to amateurs in the U.S.:

Quote
Hello,

Section 2.1049 applies to Certification.  Part 97 devices do not require Certification except for amplifiers.  What we are looking for in amplifier Certification are intermodulation products and notching of the 26-28 MHz band.  Technical and Certification requirements are in Sections 97.315 and 97.317.

Regards,

Andy Leimer
FCC/OET/EACB

So, I had to dig through 47 CFR 2.1049, which led me to 2.1046(b)(3), which states:

Quote
(3) As an alternative to paragraphs
(b) (1) and (2) of this section other
tones besides those specified may be
used as modulating frequencies, upon a
sufficient showing of need. However,
any tones so chosen must not be harmonically
related, the third and fifth
order intermodulation products which
occur must fall within the ¥25 dB step
of the emission bandwidth limitation
curve, the seventh and ninth order
intermodulation product must fall
within the 35 dB step of the referenced
curve and the eleventh and all higher
order products must fall beyond the
¥35 dB step of the referenced curve.

So, it seems that IMD product measurement and verification are part of the external amplifier certification process.  I think. Tongue

If so, the amplifier that's subject of this thread wouldn't meet the certification requirements when operated at its stated power output (and earlier in Part 2, Subpart J it does specify that amplifiers must be tested at 1500W output, or their maximum rated output power, whichever is less).

Anybody know more about that?
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K6AER
Member

Posts: 3499




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« Reply #27 on: March 22, 2012, 12:15:29 PM »

Steve,

The rated output is for test certification only. In that the amplifier meets all related FCC requirements   at rated output or below. The amplifier can be capable of more output than the rated output. I have tested amplifier for certification that were capable of almost 3 dB more output.
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WB2WIK
Member

Posts: 20565




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« Reply #28 on: March 22, 2012, 03:06:26 PM »

Steve,

The rated output is for test certification only. In that the amplifier meets all related FCC requirements   at rated output or below. The amplifier can be capable of more output than the rated output. I have tested amplifier for certification that were capable of almost 3 dB more output.

Mike, that makes sense.  In fact, it makes a whole lot of sense since almost any kind of amplifier probably is more linear and has better IMD performance when throttled back from "max."

Unfortunately "marketing" often wins over "engineering," and crazy claims are made.  I just reviewed the old Henry 3K-A manual for a local guy who just bought a used one, and see even Henry went wild the the specs on that amp.  "2000W PEP output" are listed all over the place, and that output is even specified for RTTY. Tongue

Its power supply can probably do that just fine, but you're pushing a pair of 3-500Zs up there.

When doing the external amplifier certification routine for a Part 97 amp, is IMD included in the measurement and data?

I've overseen a lot of "certification testing" for various products, but never a ham amplifier, so this is unclear to me.
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K6AER
Member

Posts: 3499




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« Reply #29 on: March 22, 2012, 07:15:07 PM »

Steve,

No IMD, its not on the FCC RADAR. They only care about out of band harmonics, case emissions and operation (positive gain) in the 26-28 MHz band.

Case emissions is strange. They must think we don't use antennas.
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