Discussion in 'Amateur Radio Amplifiers' started by WD5JOY, Oct 21, 2012.

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  1. WD5JOY

    WD5JOY Ham Member QRZ Page

    Old Senile Don is about make the purchase of an amp (thanks to the many folks out here who offered assistance in gathering info) - and I have ONE MORE query - so I best get it out of the way before I place my order!

    Fellow at a club meeting last evening said he dumped his old tube amp in favor of an Ameritron ALS-600 SOLID STATE AMP - runs about 500 to 600 watts with no tune-up etc etc. Just set the band-switch for proper frequency range -- hit the power switch and talk. QSY? Check band-switch, move it and talk. No tune up.

    Compared to the Ameritron 80B i was settled on, this does sound 'easier' -- but the idea of TRANSISTORS in an amp running 600 watts and at NEARLY TWICE the PRICE on a "watt per dollar" scale -- it seems a bit steep to me.

    SO? Anyone have experience with this little amp- possibly own (or previously owned) one? Thoughts on pro-con of transistors in HF amps?

    I see it as being easier to QSY if one does a LOT of frequency or band-hopping, but I am not sure I would be comfortable giving up the 400 watts or so --- BUT, the reduction in HEAT in the summer might be nice. In general -- I am torn and NOT overly-excited, but figured it worth a bit of input from ya'll.

    Thank Ya' - Thank Ya'!

    Don ..... WD5JOY
  2. KD0CAC

    KD0CAC Ham Member QRZ Page

    Here to see what is said about this amp , to find out more and confirm something I heard .
    If I remember correctly , I thought someone said the 600 does not do all modes - digital ?
    Also have read / heard that most all gain / affect of an amp is at or near 500-600 watts , maybe the main advantage of a larger amp would be that running 600 watts out of a 1,000 - 1,500 watt amp makes for longer life - not running all out ?
    Then the added cost of have a 75-80 amp power supply , again I would always like some head-room in running gear .
  3. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    I don't think SS amps are a FORGIVING as tube amps. I can load my SB-200, SB-230, or L7 into antennas no where near resonant and with HIGH SWR, and they just continue to play. Little hard on the tubes, but they keep chugging along. In a Solid State amp, the finals would go POOF and that would be that! Even with SWR protection circuits, they still seem to blow up.
  4. ZL2HAM

    ZL2HAM Ham Member QRZ Page

    Pros for tube amps: more forgiving of high SWR

    Cons for tube amps: warm-up time, re-adjusting plate and load after each band switch, generally heavy per watt, some tubes are becoming harder to acquire

    Pros for solid state amps: near instant-on-then-operate, some models have full-auto tuning (some include auto antenna tuner), generally lighter weight, generally more power-efficient (less heat generated per watt of output), more models available with effective internal protection circuitry, no tubes to burn out or periodically replace

    Cons for SS: much less forgiving of high SWR, more expensive per watt
    AE1N likes this.
  5. KJ3N

    KJ3N Ham Member QRZ Page

    Just a few thoughts...

    SS amps are great for quick QSY between bands. They have no warm-up time, unlike certain tube amps. They are, however pricey, compared to a tube amp for the same rated power output. They are not very forgiving when it comes to what they want to see as far as SWR is concerned. In most cases, they will fault on an SWR greater than 1.5:1. You'll either have to have very well matched antennas, or a pretty good tuner that can get the SWR below 1.5:1 in all cases.

    Tube amps are cheaper per watt, pretty forgiving on SWR, but a bit more time consuming if you do frequent band changes. If you take the time to make a tuning chart for your tube amp (similar to a tuning chart for a manual tuner), you can make band changes a bit more quickly.

    IMO, tube amps are generally easier to fix yourself. SS amps can be a little trickier to repair.

    Oh, and for the record, I have tube amps. I got to use a THP HL-1.5 for about 3 weeks. It was very nice, put I'll never be able to afford one of my own. Not sure I would want to. My AL-80B and Dentron DTR-2000L work just fine.

    Just thought of something else. Some SS amps have pretty noisy fans when they kick into "high gear".
  6. W4PG

    W4PG Super Moderator Lifetime Member 279 Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    That's it in a nutshell! Very nice!

    I have a SS amp, a PW-1 but it seems to have pretty darn good protection for SWR. I've had the wrong antenna inline a few times and it cut the power way back and prevent bad things from happening. So, if you so run with a SS amp, make sure it has some sort of protection for high SWR.
  7. W9GB

    W9GB Ham Member QRZ Page

    Don -

    The Ameritron/MFJ ALS-600 has been in production for about 20 years, and works best with a 50 ohm antenna system with 2:1 or less, across the frequencies you intend to use.
    You will need an antenna tuner (rated for 700 watts) IF you desire wide frequency agility.

    The ALS-600 (first yr. production) that I have personally seen (owned by retired engineer) had the classic MFJ QA issues:
    Poor paint finish, joints missing solder or poor soldering, failed/bad RF transistor when new, etc.
    These issues were eventually resolved over a six month period -- 2 shipments and various parts shipped back/forth.

    We may see a "Flip" from Tube to Solid-State for new amplifier purchases as soon as next 5 years.
    Broadcasters are already there ... and LDMOS is the 3rd or 4th generation of solid-state.

    Economics (price), Ease of Use, and Quality will be the major drivers of the Flip.
    IF China decides to improve quality of Glass tube production -- expect to see price DOUBLE per tube.
    KE0XS likes this.
  8. KH6AQ

    KH6AQ Ham Member QRZ Page

    I have had four tube amps and three solid state amps. I would not buy another tube amp and my favorite SS amp is my ALS-600.
  9. KM3F

    KM3F Ham Member QRZ Page

    I own both types and like the operation of both.
    Reasons are for tube amps the higher power and all self contained, less sensitive to SWR and any errors or issues plus use with antenna matching on different bands.
    Like the solid states for smaller sizes, work at vhf/uhf and seperate power supply use with any that are the same voltage and current plus being more portable when desired and no need to seperate antenna matching on those bands.
    I can repair both types as well.
    Good luck.
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    My take is similar: SS amps are fine but unless they have an auto-tuner built in (the PW-1 does, the VL-1000 does, some others do; but the ALS-600 does not) you'll likely end up needing a tuner unless your antennas are well matched. Easy to do on 30-20-17-15-12-10, not quite as easy to do on 40, much less easy on 80 and nearly impossible on 160.

    I like tubes. Unlike some others who may have had bad experiences, I really never have and all my amps (six of them) use tubes; four homebrew amps, two commercial ones.

    My old 2m and 70cm kilowatt amps use 4CX250Bs and have been chugging along since the 1970s with the same tubes in them (Eimac tubes, also from the 1970s) with a zero failure rate.

    My 4-1000A amps (homebrew) use tubes that were "pulls" when I got them, in the 1980s and those "pulls" (used tubes, purchased for $100 each) still work perfectly and put out 1500W just as they did in 1984 when I built the amps.

    My 6m 8877 amp (homebrew) also uses a "pull" I bought for $125 in 1988 and has never missed a beat, still runs 1500W output just as it did 24 years ago.

    My 3-500Z amps use Chinese tubes from RF Parts and I've never actually had one fail yet. My AL-80B uses an RF Parts (Chinese) tube and has not gone soft nor failed in any way in the several years I've owned it. I use it almost every single day, maybe 2 hours a day or so. I don't use it on RTTY or FM, and very rarely on AM, so it's mostly low duty-cycle stuff (SSB and CW) and that may help.

    As noted, a decent pi-network following a decent tube can handle a lot of mismatch issues without need for an external tuner. My little AL-80B easily tunes into a 5:1 SWR on 80m or 160m, where that is a fairly typical mismatch when you deviate a lot from the antenna resonant frequency, and has never arched or failed. Loading into a really high-Z mismatch could cause loading cap arching, but it's never occurred with mine.

    On 40m and higher frequencies I could use an SS amp just as well, as all those antennas are well enough matched across the bands that no tuner would be needed; but on 80/75m, and even more so on 160m, that would be difficult to achieve, and I'd need a tuner.
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