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hypothetical 10 meter amp question

Oct 24, 2008
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I am know there are a LOT of those illegal 11 meter amps floating around. Is there one that I can get that is actually a decent amp to work 10 meters with?

I am not too interested in putting out a nasty signal on 10 meters. I like tube stuff and I am eye ballin a Midland K1313... can I clean that amp up a bit and use it on 10 meters? Maybe even 12 meters. I dont have any need to xmit on 11 meter frequencies but the amp's are plentiful and cheap. Plus I would like the little project.

I would like to build an HF amp myself but I want to get my feet a little more wet with tube stuff first.

If your on 11 meters please don't take offense to what I said. It's just not my thing since I have a ham license :)
 

Look for a good used AL-811. Barebones amplifier but if it's not abused it'll work 80 through 10 with no problems at all. I used one for several years.

And the AL-811 is "certificated" for Part 97 use.
 
I am aware of the power limits.... I plan on taking the general test after the first of the year :)

I "guess" I am open to transistor amp's.

The way I read part 97.315 is

"(a) Any external RF power amplifier (see § 2.815 of the FCC Rules) manufactured or imported for use at an amateur radio station must be certificated for use in the amateur service in accordance with subpart J of part 2 of the FCC Rules. No amplifier capable of operation below 144 MHz may be constructed or modified by a non-amateur service licensee without a grant of certification from the FCC.

(b) The requirement of paragraph (a) does not apply if one or more of the following conditions are met:

(1) The amplifier is constructed or modified by an amateur radio operator for use at an amateur station.

(2) The amplifier was manufactured before April 28, 1978, and has been issued a marketing waiver by the FCC, or the amplifier was purchased before April 28, 1978, by an amateur radio operator for use at that operator's station......"

So I think you(an amateur radio operator) can "modify" an amp that is in violation of part 97.315 for use at an amateur radio station.

I dont really want to start a part 97 debate :blink:
That's how I interpret it.
 
You can use whatever equipment you want, as long as it meets the emissions standards. You can turn a toaster into an amp if you want. That's the nice thing about amateur radio compared to the other services. If you want 10-12 meter only, take a look at the Texas Star amplifiers. They're not bad for what they are.

But I really like the suggestion of the AL-811. You can find them used for under $500 and then you don't have to mess with buying a power supply also.
 
I run a AL-811 for the home station, it is good bang for the buck if you are not looking for a kw + amp. I find that 600 watts on SSB will more often than not do the job just fine.
I run a Texas Star 500 in my truck on Ten Meters, works great, never had a single complaint about a dirty signal while on the air.

73
Jeff
 
I am aware of the power limits.... I plan on taking the general test after the first of the year :)

I "guess" I am open to transistor amp's.

The way I read part 97.315 is

"(a) Any external RF power amplifier (see § 2.815 of the FCC Rules) manufactured or imported for use at an amateur radio station must be certificated for use in the amateur service in accordance with subpart J of part 2 of the FCC Rules. No amplifier capable of operation below 144 MHz may be constructed or modified by a non-amateur service licensee without a grant of certification from the FCC.

(b) The requirement of paragraph (a) does not apply if one or more of the following conditions are met:

(1) The amplifier is constructed or modified by an amateur radio operator for use at an amateur station.

(2) The amplifier was manufactured before April 28, 1978, and has been issued a marketing waiver by the FCC, or the amplifier was purchased before April 28, 1978, by an amateur radio operator for use at that operator's station......"

So I think you(an amateur radio operator) can "modify" an amp that is in violation of part 97.315 for use at an amateur radio station.

I dont really want to start a part 97 debate :blink:
That's how I interpret it.

I agree completely that if you're licensed, you can modify equipment to your heart's content. Problem being that you may not have access to the equipment you really need to ensure that the signal you put on the air actually does meet the spectral purity requirements.

Lacking that equipment, or access to it, I wouldn't do it.
 
I've read some on this subject but claim no expertise on said subject. What I have read indicates that you probably could get away with using the amp along with a low pass filter inline on 10m & 12m. The problem with adding a good low-pass filter, is that will only help on 17, 15, 12 and 10 meters and won't do a thing for 20, 30, 40, 80 or 160 meters. The second harmonic of 14 MHz is within the passband of all the HF LPF's on the market (or any you would likely build), and will blow right through the filter. I seem to remember a discussion with some guys on 40m one day of some figures published in QST that indicate that you'll see most LPF's don't cut off until at least 40 MHz, meaning that even 17m and possibly 15m are questionable when using them, as their second harmonics might blow right through them as well. Ameritron produces the ARF-1000 Ameritron

which is a switchable filter, I haven't talked to anyone who has used one of these, much less than with one of these types of amps. That might be another approach as well. I'm sure the ARF-1000 has some limitations as well.

Just My 2 cents FWIW.;)
 
Agreed that you will need a good LPF. Just where that lower cutoff freq is is another thing. Obviously a normal LPF is no good for anything below 17m for reasons you said.Generally what is needed is a bandpass filter for each band and those can either be purchased from a couple online retailers or built and you can build some very good filters but it is not easy. As for the run of the mill LPF's ,I use a Barker & Williamson FL10/1500 and it's upper cutoff freq is right around 32 MHz. I measured it myself and it is a steep and deep drop off above that. I remember one time I accidently left it inline and could not figure out why I could not hear the local 6m repeater on my HF/6m radio yet the handheld picked it up on the ducky antenna. Of course the filter works in BOTH directions. :headbang
 
A 10m transistor amp isn't going to put out harmonics on any band below it. Just use a 30mhz cutoff low pass filter and call it good if you're going to use a decent quality transistor amp like a Texas Star. The 2nd order IMD products wont' be much to begin with because of the push/pull configuration. The 3rd order IMD will be will within FCC specs. I have looked at a TS 500 on a Spec Analyzer. I know it will be within specs if you do that.
 
A 10m transistor amp isn't going to put out harmonics on any band below it. Just use a 30mhz cutoff low pass filter and call it good if you're going to use a decent quality transistor amp like a Texas Star. The 2nd order IMD products wont' be much to begin with because of the push/pull configuration. The 3rd order IMD will be will within FCC specs.

I believe the problem is when using a "10m" amp on 20 or 40m etc. Some will function fairly well down there due to the broadband input/outputs but the drive requirements go way down as they generally offer much more gain on those bands.
 
I believe the problem is when using a "10m" amp on 20 or 40m etc

I tried that too. Remember Justin? He tried to modify one (extensively) for me and he couldn't make it work. Long story, but just don't try it. It won't work with that amp. You might be able to get it to work down to 20m. That's about it. You can get other amps to work down there (of course) just not the Texas Star stuff.

BTW, a long time ago I emailed the maker of Worth-More Electronics about building me an external band switchable band pass filter and he said he would do it. I don't remember the cost though. Actually, this would be a fun project to build...I just don't have the time to research the details (and I don't really have a need anymore!)

Anyway, the question the thread was about was for 10-12 meters only, so I really doubt using at lower frequencies is going to be an issue.
 
Anyway, the question the thread was about was for 10-12 meters only, so I really doubt using at lower frequencies is going to be an issue.

True.I should have noted that my comments were mainly directed at Eduk8tr since he is the one that mentioned using them on other than 10-12m.

BTW, I have a little two pill 2SC2879 that will amplify as low as 80m but it requires about one watt for full power out down there. :unsure: Sure makes driving a bit touchy. I have thought about installing a gain flattening filter on the input to even out the drive levels from 80-10m and playing around a bit with a simple Pi type filter on the output in a separate box sort of like what is in an antenna tuner or in the output of a rig with tube finals. It would offer a decent level of bandpass filtering I would think.Somewhere in an ARRL Handbook there was a broadband HF amp with pretty even drive requirements from 80-10m. Hmmmm......I may have found myself a little project to work on this winter.
 

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