I've seen there is a white faced palomar 300a and a black faced palomar 300a.
Witch one is better and why??
Thanks for your input!!
Dan
Witch one is better and why??
Thanks for your input!!
Dan
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What model palomar 300a is the best??
- Thread starter radioman24
- Start date
It is my understanding that not all 300A's came with a high voltage relay to cut off the tubes when the amplifier is un-keyed. I would look for a 300A that did have the high voltage relay and CORRECT matching power supply.
Though if the deal is right (good tubes!) on a 300A without the high voltage relay, that relay is easy enough to add by a competent technician.
73
David
Though if the deal is right (good tubes!) on a 300A without the high voltage relay, that relay is easy enough to add by a competent technician.
73
David
The face color should tell you which set of innards the amplifier has. But alas, I never have pinned down which is which. Besides, anyone can switch faceplates.
The better one for my money has the relays on a small circuit board bolted horizontally to the chassis deck just beneath the Load control and the panel meter. One relay is in a socket, the other two are white plastic blocks soldered to the pc board. The older one has three identical relays with clear plastic covers mounted on a vertical circuit board that unplugs from a green socket. Those relays are no longer available, making a repair labor intensive. 45 year-old relays tend not to be terribly reliable if they have any mileage on them.
The big HV relay mentioned above appeared in some production runs and then disappeared in later versions. Grid bias is used to shut off the tubes in standby in the versions that lack this fourth relay. I haven't seen a lot of trouble from that setup, but adding a HV cutoff relay can't be a bad thing.
73
The better one for my money has the relays on a small circuit board bolted horizontally to the chassis deck just beneath the Load control and the panel meter. One relay is in a socket, the other two are white plastic blocks soldered to the pc board. The older one has three identical relays with clear plastic covers mounted on a vertical circuit board that unplugs from a green socket. Those relays are no longer available, making a repair labor intensive. 45 year-old relays tend not to be terribly reliable if they have any mileage on them.
The big HV relay mentioned above appeared in some production runs and then disappeared in later versions. Grid bias is used to shut off the tubes in standby in the versions that lack this fourth relay. I haven't seen a lot of trouble from that setup, but adding a HV cutoff relay can't be a bad thing.
73
