Which amp would you prefer?

Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, Nov 11, 2019.

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  1. VE2GCE

    VE2GCE Ham Member QRZ Page

    The Drake L7 is a nice amp. I prefer an older well built quality amplifier like this one as opposed as the modern stuff out there.
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    By giving it a "test drive" you'll find out if you like it or not.

    I think it's a pretty good amp; be sure the power cabling is in good condition. They used air system sockets and a cooling system that wasn't loud but did the job well.

    I've "used" L-7s before but never owned one. It would make a nice-looking matchup with my TR-7, which I do still own and use fairly often, so if I came across a great deal I'd be tempted, just for the cool look of matching gear.:)
     
  3. N8FVJ

    N8FVJ Ham Member QRZ Page

    Deal made, I own the Drake L7 amp. I pick up this Saturday 11-23-2019. Seller offered me an Ameritron 572 and Alpha 78 for same price. The Alpha was interesting but 60 watts drive only produced 600 watts carrier out with grid current at maximum recommended for the 8874 tubes. These are soft 8874 tubes and about unobtainable. The AL572 made 800 watts carrier with 65 watts drive. Good tubes, but Chinese 572B replacements are not great tubes and NOS Cetron are $100 each when you can find them. It also has a weak 17lb transformer- no thanks.

    The Drake L7 produces 800 watts carrier with 60 watts drive. I believe the 3-500z are very healthy tubes.
     
    Last edited: Nov 20, 2019
    VE2GCE likes this.
  4. W9RAC

    W9RAC Subscriber QRZ Page

    I run a Alpha 8410 OR Acom A2100 for SSB and a Ameritron 811H for CW. I just ordered a Acom A1200S today to replace the 811H for CW, the 811h is just not worthy with 811a tubes for CW. I hope to move away from tube amps altogether. As it is now, I actually prefer the Alpha 8410. The solid state amp may change my thinking soon. 73 Rich
     
  5. KC8GTR

    KC8GTR Premium Subscriber QRZ Page

    Oh yes , those 922's do get hot !
    Still one of the best classic amps made .
    Had mine for more than 20 years .
    On my second set of tubes , 3-500ZG , heavy duty graphite type from RF Parts .
    1,200 watts @ 248 volt mains using 85 watts drive .
     
  6. W1QJ

    W1QJ Ham Member QRZ Page

    The Drake L7 is a pretty nice amp. I have owned several of them and worked on dozens. The PS runs the tubes at a pretty low plate voltage and the output suffers a bit because of that compared to amps running 3KV+. Grounding the grids helps quite a bit to perk up the gain of the tubes and I found often times the plate tine cap will arc. I have been using a bit different design parasitic suppressor and that seems to help. Harbach has a combination board which has a soft start, soft key, and a bias board all in one. It is meant for the Drake L4 specifically but it can be modified to be used with the L7. I recently modified one for an L7 and it worked perfectly. Was able to get step start, soft key and some operating bias added all in one... The on/off CW/SSB switch is hard to get if it goes on you. PQ used to sell a rebuild kit for it and maybe still does. Probably better to save the original though with some sort of step start. The nice thing about the SS on that mod is it is about 2 seconds and really works nicely. It uses a big beefy resistor.
     
  7. N8FVJ

    N8FVJ Ham Member QRZ Page

    I made a deal on a Drake L7 and went to pick up and seller changed his mind. I ended up with an Amp Supply LK-500zb with two RF Parts 3-500ZG having about 100 house use. Likely a little better amp vs the Drake L7 anyways, but had to drive 300 miles each way to get it. Not a lot of legal limit pair of 3-500Z amps out there for under $1K now. The SB-220 is a 1kw PEP output (not 1.5kw PEP out) amp due to small 23lb HV transformer, but available for $700-$800 and many are rebuilt.
     
    Last edited: Dec 1, 2019
  8. W1QJ

    W1QJ Ham Member QRZ Page

    The Lk-500zb is in the same class of amp as the L7. Both run 3-500 tubes. The L7 of course has a separate power supply but the LK-500 has a standard Peter Dahl transformer. It is hypersil and probably a better transformer than in an L7. It does run higher plate voltage. The LK-500 also runs 160 meters as well. I have found that for the most part the LK-500 has a pretty decent input circuit with greater flexibility than the L7. The LK-500 is a self contained amp and that may appeal to some. The Drake may have an appeal with some hams who will pair it up with the TR-7 line of radios. I have owned several LK-500's and have a few on hand still. It is interesting to note that the tank circuit in the LK-500 is universal through the LK line of amps including the LK-800 which has three 3CX800 tubes and will do 4KW pep SSB. It is a solid amp easy to work on. It is definitely a step ahead of an SB-220 and just under an Al-82 amp.
     
  9. WD4IGX

    WD4IGX Premium Subscriber QRZ Page

    Well that’s great but I wanted an amp, didn’t have one, and was not inclined to pay new price. Most sellers of used amps won’t ship them, which is understandable but still limits the selection. I’d have rather had something like an AL-80B but when an AL-811H came up used and close enough to pick up I bought it. It works well if one has realistic expectations and doesn’t try to drive the snot out of it.

    I’d like to get something better someday but it’s good for now. I also need to stick to 120V amps or gave a 240 line run to the shack.
     
    Last edited: Dec 2, 2019
  10. W1BR

    W1BR Premium Subscriber QRZ Page

    My SB-220 now covers WARC and 160 meters. Would not consider anything with 811 tubes.
     

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