I think that is wonderful, and when you remember the name please send it to me.? I am at the point where I sort of forget things temporairly also, so that is no big deal.? Oh, well.? I am interested in a
lot of different technologies that all take up my time, but of course I intend to continue to stick with CW.? ? ? 73, Dan
??
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The digital voice mode that could possibly replace ssb is freedv. It is actually two things that work together.
First, the voice is converted into a stream of very few bits per second. A usual voice stream like that of telephone uses about 64,000 bits per second. Freedv codec reduces it to 700 bits per second. This is at the cost of reduced quality. However,
it is much better that SSB on 80 meters.
The second thing is an HF modem that can work at 700 bits per second. This is a weird one. On HF as signals bounce off the ionosphere and arrive at the rx antenna, you can have a situation where the same signal can arrive taking different paths
and hence at different times , overlapping itself. This reduces the number of times you can rapidly change the frequency of the signal. This is why FT8 works so well, it is so slow that fading, et al doesnt affect it. So, what the freedv modem does is that
it transmits a number of parallel ft8 like signals as separate tones within the same audio which when added up give you higher bandwidth. There is a very impressive name for it that escapes me now.
Our plan is to add freedv into the sbitx, making it the the first radio to support it natively.
- f
Gordon:
Either RadComm or Sprat had an article how students in England were fascinated by Morse code. When asked why, they replied that "voice" (SSB) didn't interest them because they could do that with their cell phone. But Morse was "better"
because their parents couldn't understand what was being said.
Any port in a storm...
Jack, W8TEE
Well, for several years now we have observed some thing very fascinating among middle schoolers in our local school.
They are not interested at all in walkie-talkies
They are not interested at all in HF radios
Don¡¯t even get me thinking about digital.
What they absolutely go crazy over, what they will grab onto and play with until you have to pull them away kicking and screaming with their parents,
Is a Morse code key!!!
At every school open house that we hold we now always provide multiple Morse code keys and it is a big draw.
We will provide them at this year¡®s field day
The news media always want a picture of someone sending Morse code
We have two 6th graders in a very small school that are already doing about 10 words per minute. I sent 30 minutes worth of code to them two weeks ago?
It is astonishing the attraction that Morse code has for these middle schoolers
Meanwhile, across town, at the school devoted to future police and fire high schoolers, they have an extremely active contesting high school I am radio club and I am told that their best operator can do over 30 words per minute and they routinely make
hundreds and hundreds of contacts at voice and CW in contests. ?
Our local ham radio club would have a hard time beating them!!!!
So I wouldn¡¯t quite give up yet. ?human nature is the same. And there are certain number of us who really love the auditory and tactile tickling that only Morse code gives¡. And by the way it is the first digital, the only digital that can be decoded by
the human brain without much else.? End it enjoys an order of magnitude or two advantage over voice In terms of threshold signal to noise ratio!!!?
On Mar 26, 2023, at 13:23, Dan Eggers N7DE <N7DE@...> wrote:
?
Thank you?for the information.? I see you and I are both CW old timers.? So far we have lost about half of the CW people without any real replacements coming along, but you and I came along during a certain era.
Best wishes.? ? ? ?73, Dan
Eventually there will be something that replaces analog single side band voice. But it¡¯s not yet here. ? And I think I have been doing CW for 55 years or more. ?
That¡¯s my thought
Gordon Kx4z?
On Mar 26, 2023, at 11:51, Dan Eggers N7DE <N7DE@...> wrote:
?
I have been sending Morse code now for 57 years, and I will just continue to send Morse code, but since you seem to be very knowledgeable is there a digital voice modulation system that will eventually replace SSB?
Thank you.? ? ? ? ? 73, Dan, N7DE?
Single side band typically requires a 10 DB signal to noise ratio for useful communications in a disaster.? That is, the efficient transfer of information
My contrast, using the same base noise in that bandwidth, data communications of moderate speed can tolerate SNR into low single digits, and still move efficient communications far faster than voice
Low data rate redundant digital communications can tolerate signal to noise ratios a couple orders of magnitude lower SNR
These comparisons are widely available
It¡¯s no secret why people who are very involved in the (voice) national traffic system often have kilowatt amplifiers. ?
And people who are into JS8 ?don¡¯t need them
So there are different requirements for different parts of our hobby
On Mar 26, 2023, at 11:33, Dan Eggers N7DE <N7DE@...> wrote:
?
I used 20 watts for a long time, and I have had a number of people refuse to talk to me, because my signal was too week, so more power is needed.? I have written a booklet about solar cells, and maybe you use solar cells and power
conversion, and that is also a very interesting area, but I also want to be able to talk to people.
? ? ? 73, Dan, N7DE? ?
With respect, Dan, "need" isn't an actionable or useful concept, especially in QRP land.
I live on a sailboat and am currently in Tampa Bay. With a couple of meters of tinn
On Sat, Mar 25, 2023 at 01:55 PM, Dan Eggers N7DE wrote:
20 w is -7 dB, and that is too far down.? it is getting close to -10 dB down.? You need to be at 50 w, and that is only -3 dB down.? What I have used for low cost has been an MRF455 in an EB63A board from Communications Concepts,
and it works very well.
?
However, the Chinese are selling a 100-w amplifier with a heatsink that has had the level set, and they also sell a lowpass filter board XDT LPF200 for 3 - 30 MHz at a reasonable price that works very well, so these days there really
isn't any reason to "build your own" amplifier.?
?
The main thing I am saying is that you need more power so that you can be heard.? I went through enough Electrical Engineering courses that I am now an Electrical Engineer, but I do not think I am going to try design amplifiers
from scratch myself.
?
I am very grateful for all of the people who helped produce the UBITX 6, because I think that has been the only low cost real general coverage transceiver that is out there.? ? ? ? ? ? ?73, Dan, N7DE
?
Hi Ted
Thanks. Incidentally the FET is? IRFP150? And Not IRF150 , sorry for the typo.
I will edit at the end of the video..
The FET i have used is Harris IRFP 150
It works great with not much heat at 35 V .
Regards
Sunil vu3sua
--
Jack, W8TEE
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