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Author Topic: Amplifier suggestions  (Read 2871 times)
N6TRU
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« on: May 04, 2019, 06:11:21 PM »

Hello all, it's Truman N6TRU. I'm nowhere near able to afford an amplifier at the moment, however, I was looking for suggestions on the options out there. I would need an amplifier with some sort of tuner when considering the fact that I have an end-fed antenna and plan on continuing to use end feds. My questions are these:

Would it be better to get an ACOM 2100 and a Palstar HF-AUTO tuner, or buy an all in one unit made by SPE Electronics (The 1.5K-FA model)?

Second, would the tuner in the SPE Electronics 1.5K-FA be sufficient enough? (I think it can match 3:1 SWR)?

Any end fed antenna suggestions? I was looking at the Ultimax DXTREME. Ideal requirements would be the same as the amp (be able to run 1500W, and operate 160-6M) as well as fit in a relatively compact space (less than 80 ft). Is the Ultimax DXTREME a good unit?

Does anyone have any other suggestions either for the amplifier? The main requirements for the amp are these: It will have a tuner, ideally can do legal limit (1500W) and operate 160-6M, and, probably less importantly, can hook up to a Yaesu FT-991.

Thanks, Truman N6TRU

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KD8MJR
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« Reply #1 on: May 04, 2019, 11:12:59 PM »

What is your highest SWR that you have now?
I would get a separate Amp and Tuner and not go for the combination but I know others may have different advice.  Did you look at the reviews section under HF amplifiers?  There is a wealth of good info on which amps are better overall.  Lastly are you more interested in a tube amp or solid state?  These answers will help someone better qualified than me give you the best possible answer.


73s
Rob
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“A lie can travel half way around the world while the truth is putting on its shoes.”  (Mark Twain)
N6TRU
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« Reply #2 on: May 04, 2019, 11:58:54 PM »

I personally don't know the SWR measurements. What I do know is that I am currently using a Chameleon Antenna EMCOMM-II for operations, which is around 66 ft (I think). However, if I purchase an amp, the antenna will likely be around 70 ft (if I buy an Ultimax model). The most important question I want suggestions on is if it would be a better idea to buy the two separately, or buy them together in the SPE unit. I would prefer solid state amps.

Thanks, Truman N6TRU
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KE6EE
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« Reply #3 on: May 05, 2019, 07:40:05 AM »

The most important question I want suggestions on is if it would be a better idea to buy the two separately, or buy them together in the SPE unit. I would prefer solid state amps.

Buy separately by all means. One step at a time.

First put up as good an antenna as you can. Make sure you have designed your antenna system to handle
high power. Deal with the matching requirements of the antenna in the design.

Very short, and/or inefficient antennas with limited power specs don't really make sense for use with high power. Using high power in a densely-populated urban area may bring many problems when RF gets into places where it causes problems with others' electronic devices.

Second or third or fourth, likely not needed, consider an amp.


« Last Edit: May 05, 2019, 07:50:48 AM by KE6EE » Logged
K6BRN
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« Reply #4 on: May 05, 2019, 09:42:32 AM »

Truman (N6TRU):

Perhaps you should start by deciding what you will be using the amplifier for and go from there.  Because you may also need to upgrade your coax and antenna if you intend to run 1500 watts, high duty cycle modes, for instance.

Many, many antennas - those that are fed by baluns, matching transformers of any type, have traps... etc, are usually limited to about 600 watts or LESS of AVERAGE power.  Some will be fine for SSB at 1500 watts Peak Envelope Power (PEP), which usually has much less average power (Low effective duty cycle - if the speech processor is not turned up too high).  But the popular digital modes of today, like FT8, transmit at 100% output for significant periods, requiring a coax, antenna system AND amplifier to be rated for the average power they will demand.  

Most amplifiers cannot sustain their ratings at average power and have to be backed off a great deal when running these modes.  But a few do not.  Beware of any amplifier or antenna that is rated as "ICAS".  For an antenna, or at the box level for an amplifier, this rating is pretty meaningless.  Actual, practical capability of any box or antenna rated this way will be WELL below its "ICAS" rating.

So... what to do?  There is a significant cost/convenience breakpoint at about 500-600 watts for an amplifier.  Above about 600 watts amps get much more expensive and you WILL need to supply the amp with 240 VAC rather than 120 VAC.  Is your "shack" wired for this?  If not, this will be an added expense.  Above 600 watts you will likely have to upgrade your antenna and coax system, especially if the antenna is nonresonant/poorly matched (STRONGLY suggest you use a resonant antenna if you will be running significant power).

Perhaps staying at or below 600 watts is a less troublesome approach.  600 watts is a great deal of usable power, especially if you can find an amplifier that can provide this as average power.   On FT8, 500-600 watts will pretty much take you anywhere in the world, with ease.

In this league, two good choices come to mind.

On the higher cost, very high performance and ease of use side is the solid-state  Elecraft KPA-500.  It can be ordered with the KAT-500 matching tuner.  Both connect to the Yaesu FT-991 or -991A seamlessly and follow it from frequency to frequency and band to band like a puppy, very automatically.  The KAT-500 tuner is compact and can match a wide range of loads (but you should have an antenna system that does not require this or feeding it with coax will become problematical).  The amp can sustain its full 500 watt output rating for a long time (average power) without breaking a sweat (it can really do about 600 watts - the very rare amp that is actually conservatively rated by its maker - but I run mine at 500 watts, a good practice, knowing it has plety of headroom).  It runs off of 120 VAC or 220 VAC - whatever you've got.  Its compact, high quality and available in what I would call  "Lego" kit form - no soldering, easy to put together.  Or you can get it fully assembled.  It's the best amp in this class.  But it's pricey:  about $2,700 for the amplifier/tuner pair.  You DO get what you pay for with this product.  Sometimes you can find them for a bit less on the used market - but they go FAST, for a reason.  BTW - I use an FT-991 + KPA-500/KAT-500 at QTH #2 - works GREAT!

On the low end, the Ameritron (MFJ) AL-80B tube amp is a good choice.  With it's pretty robust 3-500Z tube that is still available from China, it can also sustain 600 or more watts longe enough to maintain FT-8 or CW QSOs at that output level.  New, its not cheap, either - about $1,600.  But they are OFTEN available on-line, used for half or 2/3 of that price (check HRO).  As long as the antenna/feedline SWR is not over 3:1, you probably will not need a separate tuner - the manually tuned output tank circuit and tough tube will handle the mismatch - but much over that and the output bandswitch contacts may burn up .  You WILL need to learn to tune up a tube amp, and you will need to retune it every time you make a significant frequency change.  And the tubes ARE consumables, so buy a spare.  The newer Chinese ones do not seem to last as long as the original Eimacs.  Be aware that if you buy new, MFJ has what seems like a tradition of including some not-so-delightful manufacturing defects for you to discover and fix.  Usually, a used amp will have been "sorted" by the previous owner.

Have fun looking!

Brian - K6BRN
« Last Edit: May 05, 2019, 09:58:37 AM by K6BRN » Logged
K6AER
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« Reply #5 on: May 05, 2019, 10:05:42 AM »

As others have mentioned it is best to have a separate antenna tuner from the amplifier. Amplifier antenna tuners have very limited range. The reason for a separate antenna tuner is under high power when feeding high impedance antennas, the voltage on the feed line can be quite high.

An end fed antenna will work well on 40-160 meters but on the higher bands of 10-20 meters the success of a QSO is very low.  As for 6 meters, especially at this point in the sun spot cycle, a beam is needed for operation in that band.

A typical end fed balun is a 9:1 ratio with the output impedance being 450 ohms. At 1500 watts the peak voltage would be around 800 volts. Your common mode currents on the coax will be brutal.

When running power, it is best to use resonate feed antennas well away from the shack.

Solid state amplifiers cannot handle moderate to high levels of VSWR. They have to reduce power or fault to the bypass mode.

When running power, the whole shack needs to be configured for your power level. Coax, antenna switches, AC power feeds as well as the antenna have to be able to handle the power both from a continuous duty mode as well as peak RF voltages. RFI in the shack will also cause problems not to mention common mode RF coming back into the shack from an end feed antenna.

The most important item not mentioned is what is your local noise floor. If the local noise floor is high your radio experience will be quiet frustrating. If you have a high noise floor this need to be address first. It will do you no good to have a great signal if you cannot hear the contact.

If you can find a local elmer to help you through this process. This is the time to have an experienced ham to look at your installation area and make suggestions.
« Last Edit: May 05, 2019, 10:24:17 AM by K6AER » Logged
K6BRN
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« Reply #6 on: May 05, 2019, 11:10:20 AM »

Hi Michael (K6AER):

Just a few clarifications... SOME end feds can do VERY well at 20M and above, like my favorite EFHW-8010 or -4010.  A lot depends on installation.  These antenna have 49:1 matching transformers and minimal to no common mode issues.  They are a GREAT way to start a ham shack (yes, I'm a "Fan Boy" and have five of these across 3 QTHs and portable travel).  But their Achilles Heel is power. The highest power versions can only handle about 300 watts on FT8, before they overheat (matching transformer).

Nonetheless, I think I've got about 4-5,000 FT8 contacts alone on these, worldwide, from 10M down to 160M (the 160M contacts are with a EFHW-16040-2K).  And FT8 is a "young" mode.

That said, I also have a multi-band Yagi and a vertical at QTH#1.  The Yagi is the best performer by far, on the bands it covers.  The vertical is used almost exclusively for that elusive and constrained band, 60M.

You are absolutely correct about solid-state amps.  They have broadband outputs and do not have manually tuned output tank circuits that can also do some impedance transformation, the way tube amps do.  So the solid-state amps are routinely used with auto-tuners, internal or external, to do the job.  My Quadra's internal unit works fine, is automatic and fast, even at 1 KW output.  Same with the the KPA-1500, SPA amps and many others.  But they are NOT designed for use with ladder line - only coax.  If you are using ladder line, its probably because you are driving a non-resonant antenna with significant power (more than QRP) where coax losses and potential failure due to VERY high SWR is important.  In THAT case, using an external tuner (often manual) is definitely THE way to go.   Just like you, I generally prefer to use a resonant antenna and avoid this issue.

Quote
When running power, the whole shack needs to be configured for your power level. Coax, antenna switches, AC power feeds as well as the antenna have to be able to handle the power both from a continuous duty mode as well as peak RF voltages. RFI in the shack will also cause problems not to mention common mode RF coming back into the shack from an end feed antenna.

Exactly.  And 600W out is a major breakpoint between "Should" and "Must".

Best Regards,

Brian - K6BRN
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N9AOP
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« Reply #7 on: May 05, 2019, 11:16:11 AM »

If you decide to get an ACOM 2100 you can beat the crap out of it and it will still work--not so much with the SPE.  As others have said, try to cross paths with as many other hams with amps and learn from their success and failures.
Art
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K6AER
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« Reply #8 on: May 05, 2019, 12:31:56 PM »

I forgot to add.... if you buy an HF amplifier, buy a bunch of clip-on Ferrite Chokes. A package of 20 will cost about $20 from Rad Shack.com.
« Last Edit: May 05, 2019, 12:37:37 PM by K6AER » Logged
N6TRU
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« Reply #9 on: May 05, 2019, 01:33:02 PM »

I have a couple things to add:

First, I have a difficult lot to fit antennas into, so I don't have 130ft of room.

Second, my main goal with an amplifier is to be able to be able to be heard by DX traffic, (and of course be able to hear them). I was thinking of 1.5 kW power because I would like to have the versatility to do so, but then again, I would probably typically remain around the 500W-1000W range, or just whatever I feel I need for that contact.

I have one more question about these amps. Are you able to set the exact power output, such as on the radio? For example, 95W then to 100W. Or is it more like (500W to 1000W)?

Thanks, Truman N6TRU
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KE6EE
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« Reply #10 on: May 05, 2019, 03:19:25 PM »

First, I have a difficult lot to fit antennas into, so I don't have 130ft of room.

Second, my main goal with an amplifier is to be able, I would probably typically remain around the 500W-1000W range, or just whatever I feel I need for that contact.

I have one more question about these amps. Are you able to set the exact power output, such as on the radio? For example, 95W then to 100W. Or is it more like (500W to 1000W)?

If you lack room for a 130 ft. antenna horizontally, you may well be able to put up an efficient vertical antenna that
is just 40 ft. high. You will, however, have to figure out a method for providing grounding or a counterpoise or
radials. There are designs for very compact counterpoise systems for low band antennas. Google is your friend.

Getting DX with or without a high power amp will depend on your antenna. Put your thinking into installing the most
efficient antenna you can construct given the practical limitations of your location. Given size limitations you will probably have to limit your DXing to higher bands (e.g. 20M).

Google "linear amplifier." Get to know the basics because amps, as noted above, require some understanding and care
for safe and effective installation and use. Do you have access to 240V? That is a primary question. Linear amp outputs
are proportional to the input power; thus you control your output by limiting your input to the amp,
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N6TRU
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« Reply #11 on: May 05, 2019, 03:44:35 PM »

As of now, my ham shack is located in the living room of the house, where there is only 120V. However, I believe the laundry room close-by has 240 Volts(?). I was looking up verticals, and I found one made by Zero-Five which is 43ft tall and 10-160m. To be perfectly honest, I'm a younger ham, and my parents are unlikely to put an antenna on the roof. However, I might be able to get it to work out.
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K6BRN
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« Reply #12 on: May 05, 2019, 06:47:07 PM »

Truman (N6TRU):

I wouldn't count on drawing power from tbe dryer outlet, especially if you are at home with Mom and Dad.  It could get pretty awkward around laundry time, especially.

As for an antenna that occupies little space, a decent vertical really needs a good radial field.  And if you dont have the room, things get difficult.  An EFHW-8010-2K end fed wire antenna can be bent into various shapes, like a V, to conserve space, and still work well.  Its also nearly invisible.  There are also compact Yagis that you could put up.  Look at the Mosely on-line catalog.  They have LOTS of choices and the catalog is fun to go through.

So.. the amp will probably take a while.  But if you find a good, digital mode ready radio, like the Yaesu FT-991 and add a good power supply, some coax and a simple antenna like tbe EFHW-4010 or -8010-2K, you'll pretty much be able to work the world on FT8 or FT4, with "just" 100 watts.

I do, when I travel.  Usually takes about 30-60 minutes to set up (hey, I'm OLD), then I'm off and running.

Best to you and your family...

Brian - K6BRN
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K6AER
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« Reply #13 on: May 05, 2019, 08:47:49 PM »

I have this vision of a 10/3 yellow romex running from the laundry room through the house.
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N2SR
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« Reply #14 on: May 06, 2019, 01:45:47 AM »

I have this vision of a 10/3 yellow romex running from the laundry room through the house.

Yellow is 12 gauge.   Orange is 10 gauge. 

Regardless, running a "tap" off the dryer is unwise, and does not conform to the NEC anyway.   

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If no one is doing it that way, there is a probably a very good reason.
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