On Sun, Oct 17, 2021 at 11:04 PM, Jerry Gaffke wrote:

Hans has a nice 50W class C PA for the QCX if you wanted

Hi Jerry,

That is a good idea. It is so easy to only think of transceivers now days. A separate transmitter and using the uBitx, or even a SDR, as the receiver is a good alternative.?

If I did modify the uBitx, I'd try to do it in such a way as to not mess up the bias for SSB, I'd use something as simple as a relay to switch the RF source and bias when trying the digital modes.?

I just made a trip to my museum of unfinished projects. Found a box with a really nice Turkish stamp of a very happy little girl operating a soldering iron on it, and found a 10W HF amplifier kit within. Along with some low pass filter kits. This could be a good start. I image I could convert it to class C without much trouble.?

Tom, wb6b

Hi,

If I wanted to experiment with nonlinear RF finals and digital modes with my uBitx, would doing something like changing the bias and drive for the uBitx finials, driving them harder with little or no DC bias, be a practical way to do this?

Would that provide an efficiency gain that would let the uBitx putout more power (or at least generate less heat) with the same finals, without a redesign of the RF output stages?

Likely I'd build a simple digital RF chain and switch it in, close to the final stages, when I want to try these digital modes.?

Tom, wb6b

On Oct 6, 2021, at 11:59 PM, John Cunliffe W7ZQ <n2nep@...> wrote:

?The RD16HHF-1 works fine on 6m it will also work higher , I have used them all the way to 222. Both the VHF and the HF transistor are essential the same transistor only sorted for a certain gain at the upper frequency limit. Those that don't make the gain are branded for HF, Those that make the gain are branded for VHF/UHF. I have used RD16HHF-1 on 6m and 2m but they fall off above that, some do 220 within specs some not, none does 432 within specs.My 6m ,2m, and 222 transverters? all use the HF branded transistor without a problem, although I had to try several of them on 222 before I found one that worked at full gain.

John

On Oct 8, 2021, at 9:45 AM, Jack, W8TEE via groups.io <jjpurdum@...> wrote:

?

Dean:

Rex (QRPMe.com) also sells Mepads, which makes Manhattan style construction pretty easy for anyone. David Richards (AA7EE) uses them to take homebrew to an art form:

Look closely and you'll see Hans LPF in the picture. He has more pictures on his website. Everytime I visit there, I want to throw rocks at my stuff!

Jack, W8TEE

On Friday, October 8, 2021, 09:51:22 AM EDT, Dean Souleles <dsouleles@...> wrote:

On Wed, Oct 6, 2021 at 08:31 PM, Tom, wb6b wrote:

Manhattan style, seems a perfect match for these cheap CNC routers

Yes, indeed.? Here are a few more boards I cut on the CNC.? And once the design is done it's a snap to knock out another one.

Dean

--
Jack, W8TEE

On Sat, Oct 16, 2021 at 05:20 PM, Jerry Gaffke wrote:

sending compressed speech slowly to get around that 300 baud thing

I can see your point. If it turns out that the people running D-Star on HF are not pushing the regulation envelope using GMSK modulation, that could mean the possibility of a digital voice HF mode that is compatible with nonlinear RF finals. Then the slow bit rate, buffered, mode would simply be an additional way to extend the DX possibilities for people who really want to do DX and OK with a delay for the purpose.

Switching out the AMBE codec for something like FreeDV or Codec2 would be a good upgrade to a more modern codec (voice encoder) with, from what I've been reading, a two to one improvement in the bitrate needed to transmit the encoded voice.?

D-star on HF works, I already tested with a IC-7100. Of course it could
be considered a "wideband" HF mode, as it uses > 6 kHz of bandwidth. The
sad part is that the same IC-7100 does not support such wide bandwidth
in "standard" SSB mode. Anyway, freedv with LPCNet is way ahead in time,
using a much more advanced modem (and smaller bandwidth) and a
state-of-the-art AI-based vocoder.

Rafael

On 10/16/21 5:01 PM, Tom, wb6b wrote:

Hi,

This is all interesting information. I'm back in the reading mode
exploring the things that have come up in the posts.?

One would think that "advanced multi-band excitation coding" (AMBE)
being invented so long ago would be easily improved upon. But,
sometimes the fundamental design is well done and not a compromise
that was realizable with the technology of the time (circa 1990), that
it stands the test of time. Certainly would not need the expensive
custom codec chips; now that it can be implemented in software on
current microprocessor chips.?

One thing that occurred to me might be a sort of "earth-to-mars" mode.
Where each operator's voice, in a conversation, is stored/buffered and
sent at a significantly lower bit rate to the destination. This could
allow for having voice conversations under significantly reduced
signal to noise ratios, facilitating better DX communication. Albeit
with a turnaround delay for each side to pick up on their side of the
conversation. Maybe would give each side some time to think a bit
before they start speaking again to reply. Would also produce sort of
an intriguing feeling of suspense, waiting for the data stream, in the
noise, to end so you can listen the reply from the distant other
location.?

So are the folks experimenting with D-Star on HF just kind of flying
under the radar?

Tom, wb6b

Hi,

This is all interesting information. I'm back in the reading mode
exploring the things that have come up in the posts.?

One would think that "advanced multi-band excitation coding" (AMBE)
being invented so long ago would be easily improved upon. But,
sometimes the fundamental design is well done and not a compromise
that was realizable with the technology of the time (circa 1990), that
it stands the test of time. Certainly would not need the expensive
custom codec chips; now that it can be implemented in software on
current microprocessor chips.?

One thing that occurred to me might be a sort of "earth-to-mars" mode.
Where each operator's voice, in a conversation, is stored/buffered and
sent at a significantly lower bit rate to the destination. This could
allow for having voice conversations under significantly reduced
signal to noise ratios, facilitating better DX communication. Albeit
with a turnaround delay for each side to pick up on their side of the
conversation. Maybe would give each side some time to think a bit
before they start speaking again to reply. Would also produce sort of
an intriguing feeling of suspense, waiting for the data stream, in the
noise, to end so you can listen the reply from the distant other
location.?

So are the folks experimenting with D-Star on HF just kind of flying
under the radar?

Tom, wb6b

This is all interesting information. I'm back in the reading mode exploring the things that have come up in the posts.?

One would think that "advanced multi-band excitation coding" (AMBE) being invented so long ago would be easily improved upon. But, sometimes the fundamental design is well done and not a compromise that was realizable with the technology of the time (circa 1990), that it stands the test of time. Certainly would not need the expensive custom codec chips; now that it can be implemented in software on current microprocessor chips.?

One thing that occurred to me might be a sort of "earth-to-mars" mode. Where each operator's voice, in a conversation, is stored/buffered and sent at a significantly lower bit rate to the destination. This could allow for having voice conversations under significantly reduced signal to noise ratios, facilitating better DX communication. Albeit with a turnaround delay for each side to pick up on their side of the conversation. Maybe would give each side some time to think a bit before they start speaking again to reply. Would also produce sort of an intriguing feeling of suspense, waiting for the data stream, in the noise, to end so you can listen the reply from the distant other location.?

So are the folks experimenting with D-Star on HF just kind of flying under the radar?

Tom, wb6b