Discussion in 'Homebrew and Kit Projects' started by N2EY, Oct 10, 2014.
Very impressive build! Looks great, thanks for the easy to understand details on how it works!
The trick was to build with what was available, which meant some unusual choices. But after more than 25 years the Type 7 is still doing its thing.
73 de Jim, N2EY
Great works of art, Jim!
In the event of an EMP incident, you'll be the last man standing--but nobody to talk with.
Having looked at the eBay asking prices for 7360 tubes, I hope you've laid into an ample supply.
Although technically not part of the radio, I should mention the logging computer used with the Type 7.
I started with an old Win98 box and N3FJP. Earlier this year I revived an old XP machine (Dell Precision 370, with 2.79 GHz Pentium 4 processor, 2 GB RAM, 37 GB hard drive, ). This machine, a second one just like it, and the flat-screen monitor used with it were rescued on their way to the dumpster at a local business that was upgrading. N1MM software is a free download and the keying interface has already been described. By not having a whole forest of stuff on the logging computer, it doesn't take much to do what I need it to do.
The logging computer is not on the internet nor any network; it is completely isolated from the outside world except for sneakernet. Logs and such are transferred to this computer using a USB stick. At some point, this computer will probably be replaced by a newer box, and then it become the station computer.
After each contest, the Cabrillo log is printed out and put in a 3 ring binder with the paper logs used for everyday operating. (I have every log of my amateur stations, all the way back to the day my license arrived in 1967). The printer, paper and binders are - you guessed it - reused and hand-me-downs.
73 de Jim, N2EY
That's a great piece of work. I remember it being discussed back when you were working on it, but I've never seen it until now. Is it still at work in your shack?
I'm just seeing this now. Apologies for the delay.
The Southgate Type 7 is in use today. It's been in service for almost 30 years, and continues today.
In 2020, I had 8178 Qs with the Type 7. So far in 2021, we're up to 5510 Qs.
73 de Jim, N2EY
Awesome work, Jim. I would love to hear the receiver and transmit keying quality...
I really like your approach to building with a focus on performance rather than cosmetics. Although there's nothing wrong with that. Your gear screams with "real ham" quality in so many ways.
Then, if desired, take the final iteration and carefully build it to the final prototype. It allows the builder to make mistakes along the way, discover shortcomings, then rewire or reorient things until satisfaction is achieved. If we start out trying to make gear look as clean as possible, we end up with unsatisfactory, and sometimes expensive results. I've been guilty of that.
Same here, Paul. I've learned the hard way that "looks take second priority" in a lot of things I build. Although, as I've gotten better at doing it, I'm finding the two converge more and more all the time.
Trouble is, once I've got something working well but in "ugly prototype" mode, I get superstitious about messing with it. For a long time I've been planning to turn my rat's nest, battery-powered subminiature-tube receiver into a sleek radio with an actual cabinet and cool dials, etc., and even give it a name with "my callsign here" Mark One Receiver. That's because it's the first radio I've designed myself, albeit with enormous amounts of help from forum Elmers over on eHam. It is also a truly unusual design (nowadays) because of the subminiature tubes.
But I don't want to dismantle the original iteration in case it never works again when I put it back together in its sleek new cabinet. And anyway, it works really well, even if it's ugly and way bigger physically than a properly "planned" model. It works just fine, so perhaps one should just let sleeping dogs lie....
Jim's ethos of not caring too much what it looks like makes a lot of sense. Although frankly, his gear looks terrific and the layout of the controls is extremely functional. What matters is the workmanship and usability, and it has that in spades. Built like a tank, where it matters, and structural stability is really important with analogue RF gear.
Indeed Jim has at least one piece of important shack gear (I forget which) which he threw together as a prototype, and it worked so well he never got around to doing a "proper" rebuild.
73 de Martin, G3EDM
The Type 7 uses no solid-state devices of any kind. (There are two 1N34As in the SWR bridge that is in the Transmatch, however).
Sand is silicon dioxide - SiO2.
1N34As are germanium diodes, not silicon diodes.
So there is no "sand" in the Type 7. Nor the Type 6.