PALOMAR TX-5200 AMATEUR MOBILE AMPLIFIER WITH BAND SELECTOR / FILTERING

TX5200 vs. TX5300

TonyV225 said:

I am going to try this thing out I know that theres no input tuning so radios tuner will have to be used when changing bands. There was supposed to be SD1074 RF Transistors but mine has 4 X 2SC2290 thats the way I got it.

Anyways I see that its 3-4 watts input for AM / FM but what should run for input on SSB?? Im guessing no more than 20 watts?? I remember a guy telling me on 80 meters oneday when we got into talking about these true Palomars amplifiers that I should use no more than 30 watts input SSB.

Im thinking that 10 - 12 would keep it clean and not pound the hell out of this amplifier and the band I would be operating on.sure is a neat amplifier and I would expect to see 250-300 watts. Im thinking this would work well with our Kenwood TS-50 because it has the AT-50 tuner.

I can only find very little information on this amplifier here Palomar Electronics Corp. Model TX-5200

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I have the Palomar TX5300.

If I recall, the Palomar 5200 is "Class C" (check out the schematic on CB Tricks); just a couple of diodes to ground in the input toroid circuit. BTW, the schematic at CB Tricks is in error, if you look at the input Toroid Transformer, the drawing shows a 1200 ohm resistor across it, the drawing should show a 100 - 200 ohms resistor across the output side of that transformer.

If, you look at the TX5300, it is not "Class C", it has a regulated bias supply off of the MFE3055 X-sistor and, it has a 220 ohm resistor across the input transformer to balance the input power (the correct part identification).

You can "drive" and "Volt" the 5200, I would not try that with the 5300.

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anyone see a tx5300 with PIN diodes instead of relays?
i just acquired one.
maybe early production till they got too many back with killed diodes?

What frequently killed the PIN diodes on that amplifier was loss of 12-Volt power with the radio still attached.

This amplifier had to have power applied to function on standby.

Yep, the weak link in the chain was the PIN diodes.

A relay-based amplifier can be used as a barrel connector with the power removed. It won't care.

The original 5300 could only pass your barefoot power safely through it with 12-Volt power applied. Needed power to 'turn on' the PIN diodes that provide the standby path to transmit barefoot through it.

Remove power, and keying the radio would blow out the input-side diodes. Next time you key it with power applied, the output PIN diodes would fall like dominoes.

Nice idea, just a little ahead of its time. Every one of them we repaired in the 80s got converted to use relays.

Haven't seen one in decades.

73

the pin diode switching with no power is the first thing i thought of when i saw 2 of them burned.
good news is that the 4 power transistors appear to be good.
so i will fix it up as a add on to my ft-817.
it seems to have a good bias system and a real filter section not just a dummy switch.
its worth saving.

kc8adu said:

anyone see a tx5300 with PIN diodes instead of relays?
i just acquired one.
maybe early production till they got too many back with killed diodes?

Click to expand...

Do you know what the pin diodes part numbers are for the 5
Palomar tx5300a are