The Island homebrew project

[N8YX]

We have some pretty talented designers, builders and tinkerers among the membership ranks and it would be nice to see what the group as a whole could come up with in regards to usable radio equipment.

So...let's plug the irons and scopes in then get busy. But with one twist:

Each Island member designs ONE section of the project, which will be in modular format. It shall also use readily obtainable parts - as an example, filters from popular OEMs or easily obtainable surplus...or variants which the homebrewer can easily and cheaply duplicate .

A complete HF transceiver or separate receiver/transmitter might make for an interesting start.

Two requirements to start the ball rolling: Should be synthesized -or- tuned by a very stable PTO/VFO arrangement and use frequency mixing.

You folks can design either (or both) frequency generation schemes. If the forum members built one of each type, they could be swapped in and out of the parent circuit at will. Same with the other sub-assemblies.

To that end, standardize a construction and connector scheme which will allow for "plug and play" with well-defined I/O and power requirements for each board. Will you folks follow the lead of Drake (a la TR7, R7) and Yaesu (FT-90x) and Collins (KWM-380) with their plug-in, motherboard-style cards or will you emulate Kenwood's 820 line designs, which made extensive usage of header-style interconnects to the various modules...and therefore required a complex main harness? A mix of both - emulating construction techniques used in Signal's CX-11 and Milspec 1030 series? Something of our own creation?

Opening the floor for discussion of the design particulars...

[KA9MOT]

Awesome idea.....wish I had some skills....

[KG4CGC]

School's starting early on The Island. I'll watch and take notes but once my mind starts ... like breaking free old rusty wheels.

[NQ6U]

Awesome idea.....wish I had some skills....

I'll make the front panel...

[PA5COR]

Once in the far distant past made a 9 MHz i.F. transceiver for 2 meter, though that I.F could be used for other frequencies just as well.

PLL, i have some experiments done, simple around the MC 4044 i.c. and Huff and Puff stabiliser.

I think we have better people here as me ;)

[WØTKX]

What about an autotuner project?
Or maybe the Island Audio DSP?

Signal One construction technique?

Hell, let's build with surplus wire wrap!

(edited because the advanced editor dorks with the white spaces in Safari. )

[N8YX]

What about an autotuner project?

A novel idea. Perhaps it could be integrated with the project transceiver in some fashion?

Or maybe the Island Audio DSP?

See above.

Signal One construction technique? Hell, let's build with surplus wire wrap!

By this, I meant containerized (shielded) sub-assemblies which make use of SMA or similar miniature connectors for signal ingress/egress, and shielded/filtered DC supply/control lines. Hilberling, Cubic, Mackay and Collins (among many others) adopted this construction method. It allows easy substitution of "defect" modules and keeps unwanted intrastage coupling to a minimum.

I'll make the front panel...

Panels. Not just one. Everyone who participates in this effort should have at its completion a working copy of the project. In turn, the others will build and test 'their' modules for 'your' rig.

Once in the far distant past made a 9 MHz i.F. transceiver for 2 meter, though that I.F could be used for other frequencies just as well.

9MHz is also a pretty common crystal frequency, so an array of filters shouldn't be hard to fabricate from discretes. We could even make each array tunable via varicaps, allowing the operator to set each passband to his or her preferences.

Awesome idea.....wish I had some skills....

Acquire them along the way. Can you solder? Follow "kit" directions? The average ham should be able to duplicate our efforts, not just an electronics lab tech with 30 years experience in said lab. That doesn't mean we can't make the overall design robust and fully featured - it implies that esoteric or tricky fabrication procedures are to be minimized or avoided altogether.

[WØTKX]

I can accidentally cut myself and bleed on the circuit board. I have skillz.

Helped somebody dig around inside of a CX-7 years ago. It was interesting, as it was designed to be worked on. This gent was a major Elmer of mine. He swore a lot working on stuff, very lulzy. SK, I now hold his call sign.

[N8YX]

Helped somebody dig around inside of a CX-7 years ago. It was interesting, as it was designed to be worked on.

On the other hand...a lot of Kenwood gear which comes to mind wasn't, at least by the "amateur". If serviceability is important, the equipment should be designed to accommodate such from inception. In an effort such as we're contemplating, ease of module exchange is going to rank very high on the list of requirements.

Let's throw out a couple of idears here and start the ball rolling:

Transceiver/receiver/trans-receiver should employ the following frequency scheme:

At least two and preferably all HF bands.
Up-convert the first IF (~45MHz) and use a passive 1st mixer with at least +17dbM LO injection; > 23dbM preferred. There are lots of off-the-shelf 45MHz 'roofing' filters to choose from.
Use a 9MHz 2nd IF.
Use a third IF or either 455KHz or 500KHz. (The latter frequency is popular in surplus ComBloc communications equipment and a goodly selection of 500KHz filters can be obtained from eBay.)

[NQ6U]

Not wanting to poop on anyone's parade here but there is (are?) a metric shit-ton of homebrew HF transceivers out there. I'd like to suggest building a all-mode 2m transceiver instead. Try to find one of those these days; if you're lucky enough to find one for sale, it's going to cost you big bucks.