I just picked up a blue label Palomar 225 with 2 455's (see pics). I am wondering if it's possible to eliminate the delay when keying it up, and when were these made, if they are "good" amps (better than black label 225's?), and how much they should actually put out with a proper "low dead key"?
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Palomar 225 blue label help
- Thread starter fastfreddie1269
- Start date
Pretty sure the sideband-delay capacitor is the small dark-blue electrolytic seen just to the left of the big bare-wire coil between the coax sockets.
Taking it loose permanently would involve clipping it loose where it stands. But to turn the delay back on would require a switch and a working capacitor. Would be a bit tricky to do without removing the pc board from the heat sink.
73
Taking it loose permanently would involve clipping it loose where it stands. But to turn the delay back on would require a switch and a working capacitor. Would be a bit tricky to do without removing the pc board from the heat sink.
73
Thanks! I have no problem with pulling the PC board out and desoldering that cap! I want to clean the flux off it anyway and put fresh thermo paste on the power transistors.
That's interesting. Thanks for your response. This one has a pair of MRF455's, do you suppose the ones you mentioned with the SRF3749's are better, or more powerful? I gave a hundred dollar bill for it, didn't even try to talk the guy down. Excited to get variable dead key installed on my radio so I can run it! I also have a "black label" version of it (also with 2 455's) that I gave $20 for and included an old Philippines Uniden PC68XL & astatic mic. The black label amp has a badly burned resistor & some wonky wiring. It doesn't work.
The 454,455, and 3749 were all very very similar. The amp builders of that day would purchase these finals in large lots, they would build the same amp with any of the above finals. There would be no real functional difference. (note they would use the same for both finals, no running one 454 and one 3749) At some point the MRF and SRF finals became harder to get and it seems the SD1446 became very popular in many amplifiers.