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Reviews For: Galaxy 2000+

Category: Amplifiers: RF Power - HF & HF+6M

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Review Summary For : Galaxy 2000+
Reviews: 5MSRP: 450. (new in 1965)
Description:
Galaxy 2000+ Linear Amplifier. Coverage 10-80 meters. A unique sweep tube amplifier!
Product is not in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0054.4
K9SUL Rating: 2020-07-28
Interesting beast of the late 60s Time Owned: more than 12 months.
I obtained about 40 6HF5 tubes to get 10 matching ones. I had built a jig to use the linear's power supply to supply correct voltages for matching.

With the matched set of NOS tubes and a line voltage of 246V, my 2000+ easily produces 1.3kW key down, measured using a Telepost LP-500. As noted in the manual, this level of output is only for the SSB service, where the average output will be 25% to 35% of the peak. When I get 1,402W peak, the average is about 470W. There are pauses in the speech, so long term average is much lower than this. So, the long term Pd is well within the limit explained by a previous reviewer, KH6VP. If you use a speech processor, pay attention to the average power level.

The 6HF5 is rugged. It will withstand several seconds of tuning at the maximum output, provided that a sufficient resting period is followed. I tuned the amp for the maximum output and it gave me talk power output of 1,402W PEP. The trapezoid pattern looked very good at this power level. I did not conduct a two-tone test, but the 73 Magazine review said the 3rd IMD product was -30dBc at the max output. Not bad at all for a grid driven sweep tube amp!

For running at 100% duty cycle, limit the power output to 450W or less to be safe. The tubes may not be perfectly balanced, so one might die and strain others, if run close to the calculated limit. At 450W, the average Pd per tube will be about 23W.

One of the obvious shortcomings of the amp is it's cooling system. A tiny fan inside isn't ideal. I placed two 120mm by 120mm fans on the top, wired serially. They move enough volume of air and stay quiet.

EDIT: I performed a two tone test. The 3rd order IM products were down 31dB at 1,200W level, which is consistent with what the 73's review. If I push further, it quickly deteriorated and got as bad as 22dB down.

Another drawback is lack of input matching. The input will present a higher than desired SWR on some bands. This could make your transceiver fold back the output, if a tuner is not used.
KH6VP Rating: 2016-01-15
Excellent linear full of great ideas! Time Owned: 0 to 3 months.
I own many amps from a Heathkit HW-14 to an Amp Supply LK-1000A to the Alpha 87A. Everything from 400 watts out to 1500 watts output.

I have always wanted the Galaxy 2000+ linear amplifier. It was designed in the mid 60's and uses 10, yes 10 TV sweep tubes (6HF5). The 6HF5 has 28 watts of dissipation so this is like having a 2000 watts PEP input linear with a tube having 280 watts dissipation. This is not realistic, since at the 2000 watt level, you will have to change the tubes often.

When the linear was made, tubes were a few dollars each, so no biggie but now they cost >$20 on ebay so it is not practical to be changing them often.

Thus this linear should be used at the 280 * 2 = 560 watts DC input level, which means a maximum of 1120 watts PEP input, certainly not 2000+ watts input. Output is around 1300watts PEP.

The 2000+ has an automatic linearity system which compares input and output signals and adjusts bias accordingly. Really neat idea.

It also has a very hefty power supply which can provide up to 800V @ 2.5 amps (yes 2.5 amps) for a maximum input of 2000 watts for SSB and 600V @ 2.5 amps for 1500watts CW/RTTY which is obviously too much for the dissipation available. Run the linear with a maximum of 50 watts from the transceiver to keep the values to reasonable levels.

In the input signal trace there is a huge, 50 ohm /100 watt dissipation resistor to provide a nominal 50 ohm impedance to the transceiver.

All in all a great linear amplifier. A real nice piece of amateur radio history.
WB0SNF Rating: 2015-11-12
Works great Time Owned: more than 12 months.
Hi. I've had a 2000b [6lb6's] for about 25 years. I have only had it wide open once, for the cq world wide dx contest. And yes, it will do 1250 watts out with good linearity-audio. Normally I run it at about half power to baby the sweep tubes and they are the same ones from 25 years ago and they still work great. I do run a hefty muffin fan on top to keep it cool and am careful about tune up although most of the time it's parked on 20 meters. Amazingly I ran across a 2000 -6hf5's- , plugged it into my power supply and it still would put out 600 watts and who knows how much about those tubes have taken.
All in all it has been very reliable, friendly to use, well designed and is a keeper. And oh yes, I did find the missing power supply for the 2000.
73's
W5DC Rating: 2010-05-20
Poor cooling Time Owned: more than 12 months.
This amplifier worked as advertised except that it had grossly inadequate cooling.

Dunc, W5DC
WA2TED Rating: 2001-05-25
Remarkable Sweep Tube Amp from the 60's Time Owned: 3 to 6 months.
The Galaxy 2000+ is a unique sweep tube amplifier. Providing coverage for 10-80 meters the unit is compact with a very small RF desktop unit and small, but hefty power supply on a 3' cable. The Galaxy uses 10 sweep tubes! 6HF5 in parrallel producing 1350 watts out, key down. This amazing unit built from 1965-1968 sold for 450. when new. Today, 6HF5 are fairly common and the amp can be retubed to about 75.00! Not bad, 1.3kw for 75.00. Produces a remarkable linear signal with great audio reports. If found intact, grab it at about 250-300. Inexpensive to run, inexpensive to buy, inexpensive to retube. Unique circuitry even for its day, and yep, splatter free.