M
Michael Black
Guest
On Sat, 5 Apr 2008, PhattyMo wrote:
It's similar to the RCA CA3028, but never quite the same because of
the internal biasing network.
The HEP line, at least the ICs, was mostly Motorola components renumbered.
The "HEP" was of coure "Hobby, Experimenter, Professional" so it wsa
about getting parts off a pegboard rather than a completely universal
replacement line. They wanted their parts available, so that was one
way of doing it. ECG/NTE came later, and they were a far better line of
replacement parts. I seem to have discared the first HEP replacement
guide I had, I think it fell apart, but the later one dating from
about 1975 is pretty sparse in the cross-reference, and I immedately
am reminded of how often there were mistakes in that cross-reference.
I know it's an MC1550 because it was something from Motorola's line, and
that number jumped out when I was thinking about it. I looked up the
schematic, and then an old magazine article that gave a partial internal
diagram of the HEP590, and they match; even more definite is the external
pinouts.
Michael
RF work, but with an internal biasing network.
It's similar to the RCA CA3028, but never quite the same because of
the internal biasing network.
The HEP line, at least the ICs, was mostly Motorola components renumbered.
The "HEP" was of coure "Hobby, Experimenter, Professional" so it wsa
about getting parts off a pegboard rather than a completely universal
replacement line. They wanted their parts available, so that was one
way of doing it. ECG/NTE came later, and they were a far better line of
replacement parts. I seem to have discared the first HEP replacement
guide I had, I think it fell apart, but the later one dating from
about 1975 is pretty sparse in the cross-reference, and I immedately
am reminded of how often there were mistakes in that cross-reference.
I know it's an MC1550 because it was something from Motorola's line, and
that number jumped out when I was thinking about it. I looked up the
schematic, and then an old magazine article that gave a partial internal
diagram of the HEP590, and they match; even more definite is the external
pinouts.
Michael