Re: Homebrew is alive and well in Vienna Virginia #homebrew


Scott McDonald
 

......I can't think of an actual use of bidi amps in ham gear prior to the uBitx, but otherwise, it's all pretty stock as you say. ......

And FWIW even solid state bidirectional transceiver amps go back at least into the late 60s in the Sideband Engineers SBE-33 and 34 rigs - kinda neat studies in early transistor rigs for a rainy, no sunspot day.

73 Scott Ka9p

On Sat, Apr 17, 2021 at 2:44 PM Jerry Gaffke via groups.io <jgaffke=yahoo.com@groups.io> wrote:
Dean said:

>  Similarly the decision to use a commercial filter and mixers was a design decision to increase the likelihood of success for the first time builder. 

I get that.
I would probably use ADE-1's if I were to build such a thing.

>  As far as  citing sources -  most of the modules are pretty standard circuits that derive from many sources. 
>  The bi-directional IF module is decidedly not a ubitx derivative.  The bidirectional amplifiers
>  that comprise it are documented in EMRFD and were originally in a Plessey Manpack. 

I can't think of an actual use of bidi amps in ham gear prior to the uBitx, but otherwise, it's all pretty stock as you say.
Few construction articles bother to cite precedents, but I do encourage the practice.

Modules are good, and that has come up in the forum with regard to *Bitx* builds.
Several advantages, allows easy testing of individual modules, you can stack them like Legos
to build something different, an be individually shielded if necessary and have independent power supply filtering.
Though auto-inserting an entire Bitx40 or uBitx onto one board is simpler and cheaper.


>  There is no "complete schematic" by intent.  This is a project for for inexperienced builders and we take it one module at a time.

This I will argue with, sounds like a rationalization.
Describing each module separately does not preclude having a complete schematic.
I considered printing out the dozen or so pages of description, cutting out the schematic bits that mattered,
figuring out was was old history, then gluing the schematic bits together following the various block diagrams.
Concluded it was not worth the bother.
I can't imagine that process is any easier for inexperienced builders who aren't being mentored.
But tastes vary, perhaps some would find the big picture too overwhelming.

Jerry, KE7ER




On Sat, Apr 17, 2021 at 11:07 AM, Dean Souleles wrote:
Jerry -

You missed the point entirely.

20 hams, some whom had never built anything will soon have 100% scratch-built SSB transceivers on the air.  The design goal was a low part count, common component, easy to assemble rig that performs well on the air.  There is no "complete schematic" by intent.  This is a project for for inexperienced builders and we take it one module at a time.  I don't need the full rig on one piece of paper in order to build the audio amplifier stage. In fact, if I had had to start with a full schematic I would never have picked up a soldering iron.   But if you really want a full schematic, in the spirit of a community project go ahead and make one.

Similarly the decision to use a commercial filter and mixers was a design decision to increase the likelihood of success for the first time builder.  You could say the same about the SI-5351 and Arduino.  The decision to use relays for steering is also a design choice. Reliability has not been an issue to-date and if it is, they are easy to swap out. 

As far as  citing sources -  most of the modules are pretty standard circuits that derive from many sources.  The bi-directional IF module is decidedly not a ubitx derivative.  The bidirectional amplifiers that comprise it are documented in EMRFD and were originally in a Plessey Manpack. 

The result is a fine performing transceiver - I have worked much of the world SSB phone on 5 watts - and the whole world on WSPR.  I get great audio reports and the rig produces a very clean and compliant spectrum. 

It is also an experimenters platform.  The modular design makes it easy to try different design ideas - you don't like the relay steered IF - substitute your favorite circuit and share it.   Since my original build I have added CAT control via software, made it a two bander (I used relays for the BPF and LPF switches also),  Added and S-meter and audio derived gain control.  And the sketch now supports LCD's, color TFT's or Nextion displays. 


73,
Dean
KK4DAS

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