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Author Topic: TC-300, HF amplifier 150W  (Read 19468 times)
AA4HA
Member

Posts: 1640




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« Reply #15 on: November 12, 2013, 07:42:12 AM »

...
A ham can put the biggest piece of home brew crap on the air and it is legal.  Yet when someone buys something made off shore without the FCC acceptance label the sky is falling down.
...
The spectral purity of your signal is the responsibility of the operator.  No amount of harmonic filtering will cure signal IMD distortion from over driving an amplifier.
...
Here is an idea…Why not put one into operation and measure the two tone IMD and harmonic content. Look at the 1 dB compression point. Then if the amplifier needs a harmonic filter build one for the specific band of operation. Post the results and describe the project in the article section. Find out at what voltage the amplifier is most linear. Play with the bias to improve the amplifier IMD performance.
...
I look at this as a examination of human nature. If you have the talents to homebrew an amplifier then you probably have some basic understanding of amplifier design, operation and performance. These amateurs will usually be more capable of following best practices, in recognizing the different designs and limitations and in making the changes to get an amplifier working in a proper manner.

Conversely if you are buying a ready-made, off the shelf product you may have no real idea of what to test or how to test an amplifier. There are many amateurs who do not even own a voltmeter or wattmeter, much less a spectrum analyzer or how to measure IMD. They will probably never crack the case open on the amplifier and really just want a box that puts out power.

There is a big skills gap between an engineer-tech and an appliance operator. To be honest, maybe there should not be one rule that applies to everyone. We can either say that only triple-tested, CE and FCC stamped amplifiers (and radios) with >60 dB down should be certified and sold, with sealed chassis (no user serviceable parts inside) or we require that every amateur who buys a radio have at least an associates degree in electronics and a test bench full of gear.

That is the reality of the situation, very few amateurs who want a radio or an amp are going to have the skills or means to qualify that the device meets emission standards. That is why they ask questions here, to find out from "experts" if a device is appropriate.

I can go anywhere to hear a libertarian answer to "do what thou will" or parsing the letter of the law. Yes, sure, in theory that is all just great; you are indeed responsible for making sure that your station operates in accordance with rules & regs and best practices. How do we make that happen for all amateurs?
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
G3RZP
Member

Posts: 4959




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« Reply #16 on: November 12, 2013, 02:31:58 PM »

Well said, Tisha.

But there are those amateurs who are quite willing to ignore regulatory requirements. Firstly, the chance of being caught causing 'undue interference' is not that high, secondly, the authorities are pretty lax on enforcement on the amateur bands and thirdly, many of these products are low cost enough to throw away if the necessity arises.

When you have an amplifier with no output low pass filtering, you must remember that with a trapped beam, the second harmonic of 20m gets radiated well: with a 40m dipole, the 3rd harmonic of 40 gets radiated well....

So if you don't have an FCC or CE approved (genuinely approved, not just sticker applied!) amp and you don't have the technical ability or equipment to evaluate such a non-approved amp, what's the best thing to do? PASS BY and leave well alone!
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K2OWK
Member

Posts: 1077




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« Reply #17 on: November 12, 2013, 02:37:30 PM »


can go anywhere to hear a libertarian answer to "do what thou will" or parsing the letter of the law. Yes, sure, in theory that is all just great; you are indeed responsible for making sure that your station operates in accordance with rules & regs and best practices. How do we make that happen for all amateurs?
 

 
                                                                                               
 
That's easy, The FCC needs to enforce its rules and regulations. Some big fines for non compliance will straighten things out quick.

73s

K2OWK
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G3RZP
Member

Posts: 4959




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« Reply #18 on: November 12, 2013, 02:54:19 PM »

Except that resources for enforcement in the FCC, as in probably every other administration, are cut to the bone and then deep into it. So it tends to be cases of interference to primarily safety services that comes first, then to commercial users and from illegal broadcasters. In most countries,  amateur interference gets (unless it's to a safety or commercial user) little response - once described as 'you guys are sucking on the hind teat'.

That's the problem of not paying for a licence. That is why here, they made the ham licence free - no pay, no claim. I think the majority of UK hams would have been more than happy with a $75 annual licence fee that provided 3 or 4 dedicated guys to cover the country to fix RFI complaints - to and from amateurs - and even better representation at CEPT and ITU. But it would have needed a change in the law so domestic stuff such as plasma TVs and LED lighting had not to cause interference, and that would never have been politically acceptable.

Especially with all the 'green' crap we have these days - cut energy consumption but pollute the radio spectrum so low energy consumption is achieved cheaply....
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VK3ADU
Member

Posts: 1




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« Reply #19 on: February 06, 2014, 08:09:04 PM »

The TC 300 amp from China is the same product as the KL300 amp from RM in Italy.
The Chinese company appears to be a Motorola accredited vendor and have a very well equipped Lab. See their web site  http://www.hysct.com/
They use a West coast US company to do their certification testing. 
The cost of a TC300 is about $80.00 plus postage.

You can also go to the RM web site for a manual of the KL300.


 
73s
VK3PD
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YO9IRF
Member

Posts: 29


WWW

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« Reply #20 on: February 06, 2014, 10:33:49 PM »

Please ignore the CB type ratings, they're pretty much fantasy. That is about 1/3 of a linear amplifier, that would be good for about 100W in the end. You still NEED:

- idle current circuitry;
- switched low pass filtering;
- SWR and thermal protection;
- a heatsink, or at least a fan over it's case;
- remote PTT.

On CB, the small mobile resonant antennas make take the role of the low pass filters and they mostly use FM, wich is why no idle current is necessary. The SSB switch just adds a delay to the carrier operated relay, but it still remains in class C. The power transistors are rated at 70W each (140W max for the pair), but you will need to drop that to about 90-100 to keep the IMD within decent limits, and you will also loose a few watts (mostly the odd harmonics energy) in the low pass filters. The case (wich acts as a heatsink) is VERY undersized, after 10 minutes of normal operation it will be HOT; if you add a fan it will take longer to get to those high temperatures, maybe 45-60 minutes.
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AF4RK
Member

Posts: 39




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« Reply #21 on: February 12, 2014, 10:07:44 AM »

There is a fellow who tested the HLA 150 and found that it is clean below 100 watts. 150 watts is advertising. I used mine with a Flex 1500 and worked fine. I even looked at the output on a scope. It's got SWR fault protection and band filtering. There are RM amps that are CB quality. This is not one of them.
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G3RZP
Member

Posts: 4959




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« Reply #22 on: February 12, 2014, 12:24:13 PM »

How do you define 'clean'? What numbers for 3rd, 5th, 7th and 9th order IMD and harmonics on all bands?
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