ad: vanity

HV delay for GS31B??

Discussion in 'Amateur Radio Amplifiers' started by K9FV, May 15, 2011.

Thread Status:
Not open for further replies.
ad: L-HROutlet
ad: l-rl
ad: L-MFJ
ad: L-Geochron
ad: abrind-2
ad: HRDLLC-2
ad: Left-3
ad: MessiPaoloni-1
ad: Left-2
  1. K9FV

    K9FV Ham Member QRZ Page

    Hello all, I have seen a couple of schematics that have a delay to allow the filament to heat for 2 minutes before applying voltage to the anode. BUT - most schematics do not show this delay - how important is the delay?

    If required, what results from not having the delay in typical ham radio use where the amp is not used daily? shortened tube life? how much?

    Thank all of ya'll again for all the help provided.

    73 de Ken H>
     
  2. W9GB

    W9GB Ham Member QRZ Page

    Ken -

    The components and design for a tube-based HF linear amplifier (glass or ceramic) will vary based on the tube used.
    The selected RF tube is the active component -- and hence the remainder of the amplifier is designed (schematics)
    for the Care and Feeding of that Tube to the manufacturer's specifications !!

    This Thinking/Selection Process is identical to that of an automotive engineer, that selects a specific engine for a new car (or retrofit) design.
    That auto engine (the active component) determines the components (transmission, rear end, axle, etc.) that can be used and critieria limits for the final car design --
    to optimize for desired / maximum performance !

    Bob Locher, W9KNI accomplished DX operator (and CQ DX Marathon award winner) discussed this topic at the September 2010 W9DXCC.
    http://www.cq-amateur-radio.com/cq_highlights/2010_cq/04_2010_cq/Apr10Highlights.html
    Specifically he talked about the selection of his new HF amplifier for DX usage. He had decided upon ceramic tubes, instead of solid-state devices.
    His main decision criteria was to find a tube / amplifier that would provide him with Quick Tune-up Instant-On capabilities --
    in other words without a 2 to 5 minutes warm-up/time delay required by many glass or ceramic RF tubes.

    RF Triode tube data sheets - G8WRB compiled listing
    http://www.g8wrb.org/triodes/

    BTW, Bob selected the Ameritron AL-1200 which uses a single Eimac 3CX1200 ceramic triode RF tube.

    Here is the Datasheet / Specifications for your Russian GS-31b ceramic triode that you are using in your DIY amplifier build.
    http://www.kb2ljj.com/manuals/85-Tubes/Russian tubes/GS-31B.PDF

    It plainly states: Warm up time in seconds: 120, in other words 2 minutes.
    SO, the Russian GS-31b ceramic triode RF tube that you selected -- has answered your quesiton.

    w9gb
     
    Last edited: May 15, 2011
  3. K9FV

    K9FV Ham Member QRZ Page

    Thank you for the input, and as I mentioned, I had read (datasheet was one place) the tube required 2 minutes warm up before applying anode voltage, but darn if I can find very many amps using the GS31B tube with this timer circuit included. That led me to wonder just how important it was. I've got a NE555 circuit with a 2 minute delay to drive a 25 amp contact relay if required, but how do all these other folks get away with no timer?

    I don't think Steve (WB3WIK) used a time delay on his 8877 6 meter amp, or maybe I missed it?

    If it reduces tube life to half - then no big deal as I doubt I'll ever wear a tube out anyway. BUT if there are other valid reasons, then I want to include the timer circuit.

    Thanks for the input.

    73 de Ken H>
     
  4. W9GB

    W9GB Ham Member QRZ Page

    It is a matter of proper operation ... either Automatically (having the amplifier maintain that criteria) vs the Operator (remembering to wait for warm-up) for proper operation.
    Professional broadcast amplifiers and industrial/medical RF usage -- have the time delays installed. Avoiding human operator error/mistakes.

    You may have missed it.

    The G3SEK Triode board includes the warm-up function (automatically) ..
    and permits indicator lights on the front panel for reminding the human operator.
    http://www.ifwtech.co.uk/g3sek/boards/triode/triode-1.htm

    IF this was my amplifier design .. it is a very easy decision.
    Install the time delay, to prevent a human operator mistake (or dumb decision).

    RF Ceramic Tubes are not cheap ...... and whether it be grid protection or time delay ...
    the protection from human error is very CHEAP as far as component costs to save the tube.
    You have a nice new surplus tube and already have the parts, so put it in.

    For a DX operator ... the last thing he desires is for that mistake to occur at beginning of a major contest :)

    BTW, Paul - G4DCV skipped the time delay for his GS-31b amplifier build -- thinking he would manually wait the 2 minutes.
    HOWEVER he realized problems with that approach -- is now going back and adding it (G3SEK Triode Board) !!
    http://www.g4dcv.co.uk/GS31/index.htm

    w9gb
     
    Last edited: May 15, 2011
  5. K9FV

    K9FV Ham Member QRZ Page

    Thanks for the info, I've read Paul's page several times, and used some of his info. From the bottom of his webpage:
    As I said, I'm trying to determine just what the possible costs (blown tube of course), but what are the odds of a blown tube without timer? "IF" HV is applied at same time as filament voltage, will the tube blow "every time"? 1 our of 10? Or does it reduce tube life? Those are the type of questions I'm looking for answers to.

    I had thought about a "Pushbutton" to turn on the HV, and each time the power was off, no HV would be applied until the pushbutton was pressed.

    73 de Ken H>
     
  6. WA7PRC

    WA7PRC Ham Member QRZ Page

    As you might expect, Tom/W8JI has written some about indirectly-heated power tubes.
    From http://www.w8ji.com/vacuum_tubes_and_vaccum_tube_failures.htm:

    So, the idea is that the cathode must reach operating temperature before supplying current. It would also be a good idea to ensure the filament voltage/current is above the minimum amount.

    That said, I'm of the opinion that the G3SEK boards are an excellent buy - they have control, protection and proper metering built in. I'll be adding a couple more features his board doesn't provide. Yes, his board costs more than the Russian tubes. But, IMO, the board isn't expensive... the tube(s) is/are inexpensive. And the tube being relatively inexpensive, is no reason to forego protection.

    We need to get off this kick of making equipment where the cost is the most (and seemingly only) important thing. If I could build the G3SEK board cheaper, I would.
     
  7. K9FV

    K9FV Ham Member QRZ Page

    Thank you for the info and link to Tom's webpage Bryan - I had read that page a long time ago, but I didn't remember it. I do have a question - Tom writes:
    - Does that mean it's ok for the voltage to be applied to the anode but no keying of amp? For some reason I was thinking the HV could not be applied until the filament had heated for 2 minutes.

    If the voltage can be applied, but the amp MUST not be keyed, that is easier to make happen. Just put the time delay in the PTT circuit so the amp can't be keyed for 2 minutes after applying power.

    73 de Ken H>
     
  8. W9GB

    W9GB Ham Member QRZ Page

    Ken -

    You are beating a horse here -- for all the wrong reasons (as Bryan WA7PRC has already noted).
    The cost of any of the major components for an HF amplfier are more expensive than the Russian surplus tubes (today).

    For proper operation and Long Life of the RF Tube ---- it needs to come to proper and uniform temperature.
    Long Ago -- I watched Glass RF tubes crack like eggs ... due to uneven heating.

    The GS-31b ceramic triode is a surplus item (USA had tons of WW2 surplus in 1950s and 1960s) ..
    it will NOT be available or cheap forever (aka TV sweep tubes, 8873, 8875) ..
    and a direct replacement may be unobtainium in 10 years.

    The RF tubes control boards are a great idea for the amateur DIY builder --
    and serve as the WATCHDOG for the Tube and Amplifier. Your automobile/truck has been using them since the 1990s.

    Paul Hewitt, WD7S Triode Control Board has an Adjustable Warm-up Timer that Holds OFF the HV and KEY Lines.
    http://home.earthlink.net/~wd7s/triode_control.htm

    ADJUSTABLE WARM-UP TIMER; HOLDS OFF HV AND KEY LINES
    HV PRESENCE FAULT, HOLDS OFF KEY LINE IF HV NOT PRESENT OR LOW AFTER WARM-UP
    ADJUSTABLE GRID OVER-CURRENT FAULT, AUTO-RESET
    ADJUSTABLE GRID OVER-CURRENT WARNING LED
    ADJUSTABLE PLATE OVER-CURRENT FAULT, SHUTS DOWN HV SUPPLY IN 8.3 MILLISECONDS OR LESS
    STEP-START HV TURN ON, (SOFT-START)
    TUNE/ARC FAULT, UN-KEYS AMPLIFIER WHEN SEVERELY MIS-TUNED OR DURING TANK CIRCUIT ARC, AUTO-RESET
    HV PRESENCE FAULT, HOLDS OFF KEY LINE IF HV NOT PRESENT OR LOW AFTER WARM-UP
    AIR FAULT, SHUTS DOWN FILAMENT SUPPLY IF AIR FLOW NOT PRESENT WITHIN 5 SECONDS AFTER POWER APPLIED (AIR SWITCH NOT INCLUDED)

    This board is $45 and IF you desire a complete kit of parts, $135

    w9gb
     

    Attached Files:

    Last edited: May 15, 2011
  9. WA7PRC

    WA7PRC Ham Member QRZ Page

    That's what I get out of it.

    I highly recommend reading the manual for the triode board. The answer is not written in words but rather, can be followed by looking at the schematic. It really is a well thought-out unit. I see it'll be easy to add my modification.
     
  10. K9FV

    K9FV Ham Member QRZ Page

    I'll follow this thread hoping to get a definitive answer to HV ok, but no current, OR "IF" the HV must not be applied during warmup time.

    w9gb: AT $135 for the kit, and after purchasing ALL the off board components the total cost of all his protections would run much closer to $300 or more.

    Bryan, I think we're both on the same track here..... except you have so much more knowledge than me:)

    73 de Ken H
     
Thread Status:
Not open for further replies.

Share This Page