Let's see how groups.io handles image attachments. :-)
This image shows:
- The now-socketed 12MHz crystal, my first attempt at injecting a DDS BFO. The additional lead length didn't seem to break anything. ?
- The BFO connector I added. It's turned a little bit so it can easily reach the trace going into the mixer. That blob of solder connects to the bit of trace I scraped solder mask off of.
- C106, the output coupling cap from the analog BFO, removed.
- R101 (lower right corner) removed, which removes power from the BFO.
- A 10k resistor (inside heat shrink) tied to C107 for the CW injection mod, as documented by amunter in his new software. (Unrelated to the DDS BFO mod.)
Does this help?
-Mark
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On Sep 4, 2017, at 9:59 AM, Smitty, KR6ZY <mark-groupsio@...> wrote:
How DID I? As in before? Or how am I now, as in after having read other peoples' success stories?
Before: I removed the crystal and injected CLK1 (not CLK0, but they should be equivalent) into the input of the amplifiers in the BFO. That didn't work at all: deaf receiver, birdies all over the place.
Now: I put a 2-pin header, ground pin in the "top" hole of the variable cap foot print that isn't being used, and the signal pin sticking out the side, soldered to a small section of the trace going into the mixer which I removed the solder mask.
I removed R101 to de-power the BFO circuit, and I also removed the coupling cap between the BFO and the mixer. I probably only needed to do one of these, but whatever.
Then I made a cable from RG-174 with the same 2-pin connectors that Farhhan uses on both sides. I have a stock of parts, so I just made a fresh cable, not reusing anything. There's one of these 2-pin connectors on the Raduino too.
If you do this, I encourage you to keep the polarity of the connectors the same as Farhhan uses; keep ground on the same side. It just makes it easier to not have to be critical on which cable goes where.
I have these mods made, but my laptop is borked so I haven't been able to reprogram the Raduino to enable the BFO yet. Working on that now.
-Mark
On Sep 4, 2017, at 9:09 AM, Vince Vielhaber <vev@...> wrote:
How did you couple the DDS (assuming it's CLK0) to the BitX?
Vince.
On 09/04/2017 11:55 AM, Smitty, KR6ZY wrote:
I'm looking to make the BFO-from-DDS mod too and got the
Deaf-RX-and-Birdies thing too. I was hoping you'd have some wisdom on
that. :-)
to be fair, I started this before joining this group and reading the
collected wisdom of many people who are WAY more experienced than I am,
so I tried removing the crystal and feeding CLK1 to the input of the
active section of the BFO, borrowing that idea from how the VFO is wired
up. I'll try injecting the DDS BFO directly into the mixer and see if
that solves my problems.
Readers from the future! If you see this email but no replies, assume
that it worked. :-D
--
Michigan VHF Corp.
Smitty, N6MTS
