Friday, Jan. 29, 2021 — Several months ago, I bought a Heathkit HP-23 power supply on eBay for a price well worth the money ($60!). The seller noted that he had updated the power supply from a 2-wire AC cord to 3-wire cord — a nice upgrade.
After the power supply arrived, I eventually opened the box and noticed that the upgrade was less of a real upgrade and more of a safety hazard. The 3-wire cord had indeed been installed, but when the previous owner replaced the power cord, he also eliminated the fuses protecting the supply!
Apparently, the person who did the modification did not know that the original power plug also contained two 3 amp fuses, one in each side of the power cord. Later versions of this power supply (the HP-23A, B, etc.) had a circuit breaker that replaced the fuses in the power cord.
So after checking the HP-23A schematic for the correct value circuit breaker, I bought a panel mount breaker. Today I had time to finally install the breaker in the power supply.
I’m glad I took time to take both the cage off the top and the bottom cover off the HP23 … doing so revealed some additional issues to address.
While the seller was promoting the addition of a 3-wire cord on this power supply, the ground conductor was never connected to anything! Its cut off and just lays there! I suppose its supposed to make you feel safer??
The other issue is that the supply rattled when you moved it. Turns out that one of the mounting nuts and bolts that secure the chocke on top of the HP-23 chassis had come loose. The screw also provides a ground connection to one of the filter caps. I recovered the missing nut and bolt and reinstalled it.
I completed the circuit breaker install, but did not have time to connect it to a rig … yet. Since that supply arrived, I’ve noticed other HP-23s for sale on eBay with 3-wire cords and with new fuse holders installed to properly protect the supply. My supply has the original caps, so I’m hoping they’ll still be in decent shape.
SPEAKING OF FUSES. I accidentally blew one of the fuses in my MFJ-1118 DC power strip; one of the accessories I was testing ran off 12vdc thru an RCA jack, and after disconnecting the accessory, I didn’t pay close attention to the power cord; the RCA plug shorted to ground, and blew the fuse.
For some reason, I thought the fuses were spade type automatic fuses, but they turned out to be regular glass tube-type fuses. I had some replacements, and replaced the blown one.
One mod I would like to do with the power strip is install a couple of chassis mount fuse holders. There’s room to mount the fuses — which are only accessible once you disassemble the entire power strip — on the sides of the strip. It wouldn’t be difficult to do, and trust me, if you have a lot of accessories connected to your power strip, its inconvenient as hell to have to remove all those connections just to tear it down to replace a stinkin’ fuse!
Another mod I made was the value of the fuses protecting the 8 binding posts. The original fuse for those posts is like 15 amps. I replaced it with 30 amp fuses. I’ve actually shorted those posts a couple of times and blown the fuse, so its still providing sufficient protection that doesn’t overload the internal wiring.
I don’t use the binding posts to attach wiring anyway (unless its a temporary test of something). I ALWAYS use dual banana plugs. In my use, I’ve created shorts by using the bind posts as bind posts, so I sworn off using them. I’ve blown a lot fewer fuses that way.
My Hallicrafters SR-400 Cyclone transceiver and power supply are here, just not unboxed yet. Right now, the operating position in Studio C is hosting my Tempo 2020 station and my Icom IC-756PROII. I’ll need to clear those out to make room for the Cyclone.
SPEAKING OF TEMPO 2020. Years ago, one of my local ham friends was short on cash, and he asked if I wanted to buy his Tempo 2020 station for $150. I jumped on it, despite the fact I already had a complete station (rig, VFO, speaker) in my shack.
The rig, VFO and speaker ended up being scattered in the house; The rig ended up on one side of attic in a box, the speaker landed in the shack under a desk. The VFO disappeared from sight — until last week. While moving my Hallicrafters SX101A to a different place in the shack, I found that original VFO with cable, dirty with years of attic dust, but complete.
After I began using the second Tempo 2020, I found a great deal on the matching VFO and bought it. So now, I have a surplus VFO. I’m going to clean up the one that originally came with the rig and either keep or sell the more recent acquisition.
I can’t forget that I have a third Tempo 2020 I bought as a parts radio, but is complete and working. I feel sure the plastic gears are cracked, as the tuning on the transmit side is out of kilter. The original top cover on my second Tempo was apparently lost in the shuffle years ago, and I have yet to find it. That’s why I bought the parts radio — for the top cover. If I can find the original top cover, I’ll have to consider investing in replacing those plastic gears to get the radio working back to specifications.
73 es CUL … de KY4Z … SK SK …. (dit dit) ….