FPR1981
Active Member
- Joined
- Feb 1, 2021
- Messages
- 597
Last night, a friend of mine who had given me a bunch of old CB gear and promised more when he dug through the mountains of things he's accumulated through the years texted me yesterday morning telling me he had more stuff for me. Like a kid in a candy store, waiting all day for him to get off work felt like an eternity. He said that he "thought" there was a linear.
Of course my excitement then just grew exponentially.
Got to his house last night and was handed a compact Cobra 19 DXIII, a nice compact Midland 40 channel mobile, a classic cobra coffin mic, an Astatic Road King power mic, two 3-foot coax patch cords and, the linear I photographed.
Dubbed "The Page 75" by "Electronics Unlimited" in Lebanon, Tennessee, this old unit appears to be at least 100 watts, possibly 150 PEP. I cannot say specifically because I have not yet gotten a new set of meters to replace the ones I gave away when I got out of CB. I've only been back into CB radio for a couple months.
In any event, I hooked it up to my 30-amp power supply and the pilot light did not come on. I hooked up one of the mobile radios to it, and the antenna, and keyed the mic.
No relay click. Not a good sign. Time to pull the cover.
Andddddd, it's riveted on, dammit. At this point I grab the drill.
I drilled out the rivets and pulled the cover. A visual inspection showed nothing that appeared burned, nothing that smelled burned, and it was surprisingly clean inside.
I took the top of my screwdriver and tapped both relays a few times. Keyed the mic, and lo and behold, it's clicking beautifully!
Again, with no RF power meter at my disposal, I checked voltage throughout. I had 13.6v at the traces where the power wires connect to the board, and I had the appropriate voltage at all the switch points, and even to the pilot light.
This morning I conversed with some truckers on 19 and they said I sounded good. It built a reasonable amount of heat on the heatsink like a linear should with extended periods of being keyed up.
The preamp does NOT work at all. Flipping the switch on and off does nothing to change the strength of the RX. I'm not sure what it would take to fix that, but having a preamp is useful. I do have one of those Workman Lil Preamp kits that are made to be installed inside a radio. I wonder if it could be installed in it??
I ordered a set of PDC 600s, but in the meantime, I ordered new 12V LED pilot light replacements.
I researched the "pills" inside this amp. They're Motorola MRF450A NPN Silicon Power Transistors, rated at 50w. Replacements would be $37.50 apiece if it needed them.
Hopefully when my meters get here, I will be happy to see this unit performing.
Of course my excitement then just grew exponentially.
Got to his house last night and was handed a compact Cobra 19 DXIII, a nice compact Midland 40 channel mobile, a classic cobra coffin mic, an Astatic Road King power mic, two 3-foot coax patch cords and, the linear I photographed.
Dubbed "The Page 75" by "Electronics Unlimited" in Lebanon, Tennessee, this old unit appears to be at least 100 watts, possibly 150 PEP. I cannot say specifically because I have not yet gotten a new set of meters to replace the ones I gave away when I got out of CB. I've only been back into CB radio for a couple months.
In any event, I hooked it up to my 30-amp power supply and the pilot light did not come on. I hooked up one of the mobile radios to it, and the antenna, and keyed the mic.
No relay click. Not a good sign. Time to pull the cover.
Andddddd, it's riveted on, dammit. At this point I grab the drill.
I drilled out the rivets and pulled the cover. A visual inspection showed nothing that appeared burned, nothing that smelled burned, and it was surprisingly clean inside.
I took the top of my screwdriver and tapped both relays a few times. Keyed the mic, and lo and behold, it's clicking beautifully!
Again, with no RF power meter at my disposal, I checked voltage throughout. I had 13.6v at the traces where the power wires connect to the board, and I had the appropriate voltage at all the switch points, and even to the pilot light.
This morning I conversed with some truckers on 19 and they said I sounded good. It built a reasonable amount of heat on the heatsink like a linear should with extended periods of being keyed up.
The preamp does NOT work at all. Flipping the switch on and off does nothing to change the strength of the RX. I'm not sure what it would take to fix that, but having a preamp is useful. I do have one of those Workman Lil Preamp kits that are made to be installed inside a radio. I wonder if it could be installed in it??
I ordered a set of PDC 600s, but in the meantime, I ordered new 12V LED pilot light replacements.
I researched the "pills" inside this amp. They're Motorola MRF450A NPN Silicon Power Transistors, rated at 50w. Replacements would be $37.50 apiece if it needed them.
Hopefully when my meters get here, I will be happy to see this unit performing.
