Tuesday, May 10, 2011
Heathkit SB-310 Receiver
I bought this from a very nice young couple that found it at a yard sale, and listed it on eBay. I was able to pick in up in person, as they don't live to far from here, and we agreed to meet at a SixBucks Coffee shop about half way between their place and mine.
It was exactly as they described it, and pretty clean considering it's about 45 years old. The matching SB-600 speaker that came with it has the typical Heathkit/Hallicrafters "peeling paint" syndrome, as back "In The Day" they didn't prepare the aluminum cases for paint they way we do now.
I pulled it from the case, and dusted it out with a soft paintbrush, and then proceeded to clean the tube sockets, switch contacts, and potentiometers with some Caig DeOxIt, and lubed the ball detents on the switches with a drop of gun oil. The mode switch was stiff and hard to turn, so I pulled the knob off and used a drop of light penetrating oil on the bushing where it comes through the front panel, and let the radio sit for a couple of hours with the front panel up so the oil could get in to the bushing.
While that was happening, I checked all the tubes with my EICO 667 tube tester, and surprise! They were all good. They were also all original Mullard and Tung-Sol tubes, which is what Heathkit supplied back then.
After putting the mode switch knob back on, and plugging all the tubes back in, I let it and my signal generator warm up for a couple of hours, and started in on the alignment.
Boy, was it ever out of whack!
The worst were the Heterodyne Oscillator (what Heath called the 1st Local Oscillator) coils, which required 1~3 turns of the slugs to get them back in spec. The 1st IF cans weren't too bad, but peaking them (1/2~1 turn) really made the noise level come up. The antenna and RF Amplifier coils were about as far off as the H.O. coils, and by the time I had everything peaked, signals were coming in without an antenna!
I had to put a dummy load on the antenna connector so I could go back through the alignment again, and make sure everything was adjusted right.
The last things to address were the S-meter calibration pot, and the Preselector variable cap. The S-meter pot was out of adjustment, resulting in the meter being "Off Scale Negative", and the Preselector cap was noisy as I turned it. A drop of light synthetic oil cured the cap, and adjusting the S-meter pot brought it back in line.
I still have some cleaning and polishing to do, and I have to install the 400Hz CW filter I bought for it. I'm also going to replace the original frosted "#47" pilot light bulbs with some of the frosted white LED lamps made just for this purpose, and this old warhorse will be ready to cruise the bands again.
My first "real" Amateur Radio receiver was a Hallicrafters SX-146, which was a present from my parents for passing my Novice exam back in 1964. My Dad had some friends who were "into" radio, and they all told him "Get the kid a GOOD receiver so he can hear the other stations, or he'll lose interest fast", so he consulted with them for a good one at a decent price (sorry, NO Collins gear!), and they gave it to me the day my Novice license arrived. When I upgraded to General Class about 10 months later, I had saved up enough money to buy a Heathkit SB-301 receiver, and an SB-401 transmitter, and Mom and Dad kicked in the extra money so I could get the crystal pack for the transmitter allowing 'split' operation, and the CW filter for the receiver. They also bought me the matching SB-600 speaker, and the SB-630 station console.
The SB-310 is the General Coverage version of the Amateur Band only SB-301, so it's like having an old friend return after many years.
No, it doesn't have all the bells-and-whistles that new radios have, and the audio is a little "hissy", but it's very sensitive, has decent selectivity with the crystal filters, and is rock solid stable after it's been operating for half an hour or so.
And it's got TUBES in it so it Glows In The Dark, and will probably survive an EMP!