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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | SB2-LA Help

Reviews Summary for SB2-LA
SB2-LA Reviews: 2 Average rating: 4.0/5 MSRP: $$395 in 1965.
Description: Linear amplifier to match the SB-33 and SB-34 transceivers.
It runs off 110V, uses 6 sweep tubes, self contained, easy to use. 1000Watts input and it produces about 600Watts output. SSB service only. Uses the 6MJ6 tubes, or 6LQ6, whichever available. Nice simple design, rather squeezed inside.
Product is not in production.
More info: http://
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K3MD Rating: 4/5 Feb 15, 2016 18:20 Send this review to a friend
Rugged  Time owned: 6 to 12 months
This is my second SB2-LA. Got it on EBay from a radio recycler in Md. I had to replace the filter caps with higher capacitance value units to combat hum.... initial report on the air were T8. I used ALL Electronics 400V 140uFd electrolytic caps. The filter cap board is very easy to get to. The keying line is -140 volts... you must use an Ameritron ARB-704 or homebrew external 12V relay, or you will blow out the keying transistor or relay in your modern rig. You could also put in a Harbach board. I did not put a 12V relay inside the case for rear of messing up the complex bias/cutoff circuit. Drives well to 400 to 600W out. Input circuit is non-inductive resistors, a la Alpha 76, HF-2500DX, etc. Drives well without a tuner in the exciter. Easy to tune... unit has output meter and "tune"(reduced power) tune-up switch. Replacement used/good 6LQ6 tubes run $15-20 each on EBay. The tubes have NO TVI parasitic suppressors, but rig has suppression circuit in grid circuit. I place a nice big 120V muffin fan on the top..... keeps things cool. Unlike some sweep tube amps, runs 800V on plates, not 1200V.... tubes are not as stressed. This unit is very solidly built. Use as amp at summer cabin.
KH6VP Rating: 4/5 Feb 11, 2015 00:48 Send this review to a friend
Excellent for its time  Time owned: 3 to 6 months
Very simple excellent linear amplifier, squeezing its parts and an ability to get 1000watts input, using six sweep tubes (6MJ6) which at 33 watts dissipation each, provides for 198 Watts total of dissipation, rest as RF power, mainly for SSB use only. Matches the SB-34 transceiver, also from the mid-sixties.
Interesting simple design, covers 80, 40, 20 and 15 meter bands only.
Can be used with modern transceivers. Power supply built-in; only 110V [no 220V possible]. Includes TX/RX relay (many from that time didn't).
Was designed when sweep tubes were dime a dozen; can use other tubes [6 PL519 can be used with filament connected in series, tied to a 240V line for example].

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