Want to hook this stuff up atleast once before I put it on the market. Any help with operating procedures would be appreciated.
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Drake r4c and t4xc also l4b
- Thread starter Homewrecker
- Start date
Powering up equipment that may be 50 years old or close to it presents hazards. The radio, and especially its power supply contain capacitors that will deteriorate from age alone. If they break down and become shorted inside, this risks collateral damage to other parts of the radio.
There are techniques to do this safely, mostly involving a source of variable AC voltage to power up the radio gradually and a way to limit fault current to a safe level. That way any parts that fail as a short circuit can't scorch the rest of that circuit.
But simply plugging it into the wall outlet and flipping the power on is called a "smoke test". That is, letting out the smoke is easier than putting it back in.
And leaving the smoke in there, is cheaper than letting it out.
This is especially true in the L4B amplifier's power supply. Bigger parts tend to "fall harder" as they say. And if the eight electrolytic filter caps in the L4B's power supply are original, there is very little chance they'll still be okay. That kind of capacitor will frequently be visibly distressed. Bulges in the rubber end plug, or precipitated dusty brown stuff where liquid leaked out are an immediate clue if you see that.
Unless someone updated all four units in the last 20 years, this will be like finding a 1974 'Vette under a tarp in a barn. Would be nice to make it driveable, but the list of issues to address first will be pretty long. Can't just jump in, gas it up and drive a thousand miles.
The manuals for those items should be online somewhere. I recommend you NOT power up the L4B at all. Unless you have a hookup to safely absorb a thousand Watts of RF energy, there is no point to plugging it in at all. And probably a few good reasons NOT to.
73
There are techniques to do this safely, mostly involving a source of variable AC voltage to power up the radio gradually and a way to limit fault current to a safe level. That way any parts that fail as a short circuit can't scorch the rest of that circuit.
But simply plugging it into the wall outlet and flipping the power on is called a "smoke test". That is, letting out the smoke is easier than putting it back in.
And leaving the smoke in there, is cheaper than letting it out.
This is especially true in the L4B amplifier's power supply. Bigger parts tend to "fall harder" as they say. And if the eight electrolytic filter caps in the L4B's power supply are original, there is very little chance they'll still be okay. That kind of capacitor will frequently be visibly distressed. Bulges in the rubber end plug, or precipitated dusty brown stuff where liquid leaked out are an immediate clue if you see that.
Unless someone updated all four units in the last 20 years, this will be like finding a 1974 'Vette under a tarp in a barn. Would be nice to make it driveable, but the list of issues to address first will be pretty long. Can't just jump in, gas it up and drive a thousand miles.
The manuals for those items should be online somewhere. I recommend you NOT power up the L4B at all. Unless you have a hookup to safely absorb a thousand Watts of RF energy, there is no point to plugging it in at all. And probably a few good reasons NOT to.
73
BJ radionut
Supporting Member and 6m addict
PM-400 Replacement Power Supply Module for L-4/L-4B/L-7 Amplifier | Harbach Electronics, LLC
ES4L4-B Soft-Start/Soft-Key/Bias Module | Harbach Electronics, LLC
These are just 2 updates to L4B alone!
Having done several of these restorations average cost is about $300 USD in parts alone. The new tubes are around $500 USB. Updates require average 6 -20 hours labor, to properly clean, remove outdated parts and build and install new.
Last L4B I purchased, which was stated to be in "working" condition "when removed from service" (3-4 years since used) the 3000 volts DC in the power supply would have gone off like 10 ga shotgun!!! Deadly! "Just to see IF it powered-up."
The same applies for the T4XC Transmitter=1000 volts DC inside the cage, plus inside the separate power supply cabinet
Last: L4B restoration cost was near $900 USD...parts/labor/NIB Tubes...Similar cost for T4XC/R4C...if it goes "BANG" when powered "ON" Double that for each piece.
As you can see total restoration for T4XC ALONE is close to $500 USD
Do what you wish... GL...
One such, L4B I purchased in stated condition (working when last used) was $500 USD and came shipped from NY to Indiana with NIB set of replacement tubes...
All the Best
Gary
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