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

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I have five (with toobs) and like them all.

    The tube PA transceivers I've owned all had better IMD performance than my modern SS transceivers do; in fact my old FT-102 (never should have sold that) measured IM3 & IM5 at -47 dBc or lower (IM7 and beyond were well below that). I've never had an SS transceiver that clean.

    But that was then and this is now. My SS TS-850S measures about -30 dBc for IM3. The K3 is around there also (although I don't have one to measure, I'm just going by the ARRL report for that).

    As operators we place a lot of value in receiver performance and probably less than 1% of all hams have any ability to measure TX performance much beyond output power.

    Marketing is great stuff.:eek:
  2. WA7PRC

    WA7PRC Ham Member QRZ Page

    The Chinese 3-500ZGs in my SB220 have been fine for over 5 years, with almost daily use. I read many amplifier email reflectors, and haven't noticed any chronic problems with them. Most failures seem to have been due to gassy tubes that've been sitting a long time -- common to all 3-500Zs.

    Anode/collector/drain dissipation is about the same, for a given power level and class of operation. Just don't use tubes that eat a lot of filament power (toobs with directly-heated cathodes such as 3-500Z, etc). The 3-500Z consumes 5V x 14.5A = 72.5W. The 3CX800 uses 13.5V x 1.5A = 20.25W. The popular Russian GS-35b (PDISS=1500W) pulls only 12.6V x 3A = 37.8W. Tube or transistor, if you want cool operation, you want to consider water cooling.
  3. N2EY

    N2EY Premium Subscriber QRZ Page

    What's the answer, then? IOW, what should hams do?


    It occurs to me that we may be seeing an historical cycle.

    In the 1920s and 1930s, few hams ran high power. The tubes and parts to do so were just too expensive. The situation hit bottom during the Great Depression, both because many hams were struggling just to live, but also because the 1929 regulations required pure DC and a cleaner signal than ever before. There weren't many high-power tubes to choose from, and the cost of a power supply and other parts was considerable.

    High power 'phone was even rarer, because of the cost of a high power modulator.

    Of course some hams got creative and pushed things a bit. My favorite is the ham who ran a pair of 852s at 4000 volts and 1 kW input (was in QST about 1934). But for most hams, 100 watts was a considerable undertaking, and 1000 the stuff of dreams.

    After WW2, it became easier to run high power. War surplus and electronic developments lowered costs and post-war prosperity gave hams more spending money. The increased popularity of SSB made high-power 'phone less expensive and easier, and the development of grounded-grid amps with solid-state power supplies lowered the cost still more. By the 1960s you could put an SSB transceiver and 1200 watt PEP amp on a card table for less than $700 (SB-100 and SB-200). There were even amps using sweep tubes (!) for the ultimate in low cost.

    Through the 1960s, 70s and 80s this situation was relatively stable (when you adjust for inflation). SS amps appeared but cost so much at first that they seemed reserved for special purposes.

    But since the 1990s we've seen higher prices and diminishing choices. The first ham HF SS amp I saw was in QST for April, 1976, and back then I figured tube amps wouldn't last long, but here it is 35+ years later and the discussion continues.

    Are we coming to a point where high-power ham stations will become rarer and rarer because the supply of tubes dries up and the cost of SS is too high? Is the historic cycle being completed?

    Or will there be some sort of breakthrough or event (such as WW2 surplus) pushing prices down?

    73 de Jim, N2EY
    NQ1B likes this.
  4. N2EY

    N2EY Premium Subscriber QRZ Page

    I am glad they are working for you.

    But from what I've read and the hams I've talked to, getting good tubes has become more chancy. Sometimes you get good ones, sometimes not. There was an ill-conceived article in QST some time back about lowering filament voltage in an AL-80, trying to extend tube life. Prices keep going up and up, too.

    In the bad old days, one could buy a pair of Cetron 572Bs or an Eimac 3-500Z and you KNEW you were getting good bottles.

    73 de Jim, N2EY
  5. KB0OU

    KB0OU Subscriber QRZ Page

    My AL-1200 has been working fine for years and will probably outlast me. ;)
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    It sure might; but then, if it has an Eimac tube in it, that's a bit like buying gold today...I think a new Eimac 3CX1200A7 (or D7) is close to $1000 now.

    I had one in my Henry 3K Premier (that used a YU-121/3CX1200D7 which is still going strong since it was new in 1985) and back then they cost about $250.:eek:
  7. KH2G

    KH2G Ham Member QRZ Page

    SS blocks are being used in many if not most commercial radio broadcast stations now days and to get the power they cascade them using 1KW (give or take) blocks which is nice because if one block fails, you just lose a bit of power til you fix it. I like both but just because of the fact I grew up on mercury vapor rectifier,813's, 4-1000 etc I use tube amps at home and I might add I don't spend a lot of key down time in my loading even in a dummy load -hi
    Oh BTW I don't do contests so no need for fast QSY and a little touch up as I go along the band doesn't take any time.
    Go how you feel best is my advice. 73 happy new year Dick KH2G
  8. W7MMQ

    W7MMQ Ham Member QRZ Page

    Eimac 3cx1200A7 are going for $1,500 minimum now.

    I too have a henry 3K Premier that I got in 1990 and still with original 1200A7 tube. Still puts out full power on all bands. Great tube, but if it croaks not sure the expense is worth replacing it.
  9. N2EY

    N2EY Premium Subscriber QRZ Page

    This got me to thinking...

    What did a 3-1000Z cost 45+ years ago?

    Way back when I became a ham in the mid-1960s, the ultimate amplifier tube (to me) was the 3-1000Z. One bottle that would handle the old 1 kW legal limit with no sweat. I saw designs for homebrew amps using the tube, but I don't recall any manufactured ones that did - a pair of 3-400Z or 3-500Z being the usual design. I think this was because the tube/socket/chimney cost of two '500s was less than the cost of a single '1000.

    $210 back in 1966 inflates to about $1500 today. So if a 3-1000Z cost $210 back then....and a 3XC1200A7 can take more power.

    Just wondering.

    73 de Jim, N2EY
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I remember the BTI amps quite well. My friend Steve W3BQN had one, and I used it at his station in one of the contests back in about 1980 or so.

    But re Barry Electronics, I used to visit there pretty often back in the 1970s and remember "Kitty."

    Do you remember "Kitty?"

    I can't imagine what the overhead would be on a small ham radio store in Manhattan. Might have been a good place for it in the 1940s or 1950s, but much after that...way too expensive. They were downtown, on Broadway. I always wondered how they came up with the rent for that place...I may have missed the drug dealings out of the basement or something.:p Meanwhile, Terry at AES had it going in Milwaukee...a place where a storefront is probably 10% the cost of Manhattan.
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