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Russian G-811 Tubes & a Cheap HF Amplifier

Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, Jun 7, 2019.

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    yold You are strapped for cash, but want an HF amplifier. Even the priced of a used Ameritron AL-811H is prohibitive. Some inexpensive 811A amplifiers are available, but the Chinese 811A tubes fail early. And, the 400 watt output sweep tube amps may not produce enough power plus the tubes are very expensive. Even worst budget wise may be on a fixed income such as SS and future tube costs are an issue too. Chinese 811A tubes may not last 2 years.

    Not well known are the Russian built G-811 tube. Starting with the letter 'G' throws off most looking for cheap 811A tubes on eBay. The G-811 is a very well built tube like 1940s thru 1960s 811A tubes and last a very long time. The good news is the G-811 is available new from the Ukraine for $13 each including shipping. The plate is not the same as older RCA 811A with the horizontal plates. But the tubes hold up well at 600 watts PEP output. Just do not take more than 5 seconds tuning the amplifier or risk burning holes in the plates. Keep a record for tune and load settings for each band and this issue goes away.

    I seen vintage 811A amplifiers for $300 on the Ham Radio sites & ebay plus under $300 at Ham swaps. These $200-$300 HF amplifiers includes the Heathkit Warrier HA-10 and the Gonset GSB-201. The amplifiers do not have a tuned input but four 811A tubes have about a 2 to 1 SWR. And no tuned input is great for the WARC bands. Plus, your SS HF transceiver may have a built-in antenna tuner. You will also need a keying interface to reduce the amplifier high voltage keying in the HA-10 or GSB-201 to low voltage as to not damage your transceiver. The keying interface is around $30.

    If you have some skills or should develop skills to replace the old HV electrolytic capacitors in the HA-10 or GSB-201. The capacitors are available for about $5 each in the 'snap-in' design and even less at surplus stores. Careful with the high voltage, unplug the amplifier and use a screwdriver with an insulated handle to short the HV to ground before working on any tube amplifier.

    If you get lucky and find an Ameritron AL-811H for under $400, buy that amp. It does not need a keying interface or new HV capacitors. And, remember the Russian G-811 tubes as it is the best deal on the planet!

    Good luck on your search.
     
    Last edited: Jun 7, 2019
  2. N8FVJ

    N8FVJ Ham Member QRZ Page

    BTW- The Heathkit HA-10 may or may not have Dow Key relays. If not, you need a set of these relays or install a double pole, double throw 20 amp relay and a power source for the relay coil. I would use 12 volts DC for the relay coil.
     
  3. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    With the HA-10 "Warrior", you also need to add a bias voltage source to "cut off" the 811A tubes when not transmitting. Otherwise, there is often a "hash" generated by the tubes that causes interference when receiving. This is outlined in the manual.

    There is plenty of room inside the cabinet to add a simple bias power supply and a DPDT relay can be added, also inside, to handle the antenna changeover and make the antenna input / output just like "modern" amplifiers. The cost, of the parts needed to accomplish these modifications, should not exceed $20.00 and, if you look around for the parts, may even not exceed $10.00.

    The person, who had previously owned my HA-10 "Warrior", had already made these modifications. As such, I did not have to even think about doing such.

    My "Warrior" is in the last photograph at the following URL:

    http://nebula.wsimg.com/f072cd32adc...50C433DB440D6B60D&disposition=0&alloworigin=1


    Glen, K9STH
     
  4. N8FVJ

    N8FVJ Ham Member QRZ Page

    Glen, you have a huge shack with vintage gear- wow. Just one FT-991A for me. Bias issue is same on Gonset.
     
  5. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    FVJ:

    It has taken 60-years to acquire the equipment! Almost all acquired used and well over half in trade deals or in exchange for working on "boat anchors" for others. If averaged over the 60-years, probably less than $150.00 per year if that much!

    I have never worked on one of the Gonset HF amplifiers (have worked on a couple of the VHF amplifiers made for the Communicator units). But, hash from 811A tubes unless a cut-off bias is applied, was pretty common in the "goode olde dayes"!

    Glen, K9STH
     
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    Glen, your experience with vintage gear is great.
     
  7. N8FVJ

    N8FVJ Ham Member QRZ Page

    As a reminder, if you need 811A tubes buy the Russian G-811 tubes on ebay that are far superior to Chinese 811A tubes. Cheaper cost too.
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Depends on the Gonset model.

    The later models had bias keying and also internal T/R relay; the earlier models didn't.

    But a "plus" is they are cavernous inside and very easy to work on, so all this stuff can be added, easily.
     

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