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Author Topic: Palomar DX 400B  (Read 689 times)
KG6KEC
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Posts: 9




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« on: September 08, 2005, 04:57:46 PM »

I just picked up a Palomar DX 400B amplifier at thrift store, got no paperwork.  It powers up and the seals are still intact.  What freq's is it designed to work on? I hoping Amateur bands and not CB.

73's
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K0BG
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Posts: 9886


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« Reply #1 on: September 08, 2005, 05:34:46 PM »

Sorry to disappoint you, but it is a CB amplifier irrespective of what the labeling says. It has no output filtering. It's use on the amateur bands is verboten. I suspect you could use it on 10 meters, but you'd have to design, and build a bandpass filter for it. What ever you paid for it, was too much.

Alan, KØBG
www.k0bg.com
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WB2WIK
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Posts: 20636




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« Reply #2 on: September 09, 2005, 08:24:49 AM »

Alan's right.

I see the DX-400 models sold under various names including "Palomar" and "Texas Star" (these two appear to be the same amplifier, different name only) at the local Swap Meets for about $100 complete with manual, carton, power cord, etc.  This is indeed a "CB" amplifier, tuned for 27 MHz operation, not legal for sale in the U.S.  Probably will work on 10m, but I'd be careful.

These amplifiers also "overdrive" quite easily, and putting 10W into one can easily damage it permanently.  If you want to try it out, use the 10m band, and a dummy load and wattmeter, and start out with about 2W drive.  If it works, you'll see it generate considerable (nearly full) output with this very small amount of drive.  To feel confident about using it on ten meters, I'd attach a good 1 kW rated 30 MHz low-pass filter to its output port -- many are on the market and suitable for this.

WB2WIK/6
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KG6KEC
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« Reply #3 on: September 09, 2005, 08:34:08 PM »

Thank you very much guys, I got it real cheap ($3.50)so it is no great lost.  I am not going use it at all it is going up on the self in the closet.

73's
JC
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W9GB
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Posts: 2656




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« Reply #4 on: September 10, 2005, 11:31:03 AM »

JC -

Palomar as an amplifier building company has been gone for a number of years -- new units appear with their name from the illegal domestic mfg. operations and illegal export.

Some of the original designs from the 1970s, were direct copies of Helge Granberg's PC board layouts from the Motorola application notes. Of course Motorola was never paid $$ for these infringements.

You might as well open it up, take a few photos and note the transistors used (likley "2SC" bipolars).

Useful for a few parts (e.g. heat sink, transistors)in building a "good" amateur radio HF amplifier!

Greg
w9gb
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