|
LPF kit and 50W amp
I've finally gotten around to trying to multi-band the 50w amplifier.? It may be a lost cause but it is fun anyway.? I have three LPFs built; 40m, 20m, and 10m.? I also have the LPF relay kit built.? The first thing I want to check is, am I planning to wiring it into the 50w amp correctly?
I plan to run a short stretch of coax from each side of C9 to the LPF input and then the LPF output goes to C21.?? Here's a picture from the 50w amp book (pg. 10). If I have my tap points correct, my next question pertains to the QDX.?? I need 5v and control signals that are active low.? I will use a microcontroller if I need to but it seems like the LPF 0 1 2 pads are the way to go with a simple transistor in circuit to invert the signal.? Also, can I rob 28mA off the QDX 5v regulator somewhere or am I risking it?? I have a QDX V3.? It seems like the 78M05 regulator is robust enough since it is rated at 500mA.? I could rob 5v off IC2 right next to the antenna port. Thanks for any tips. DE Joshua in Moab, UT KJ7LVZ |
|
Re: Don't Look Back, Look Forward...FreeDV
DMR uses the AMBE voice codec from DVSI at 3600 bits/sec, not counting the additional bits set aside for forward error correction. DMR uses a newer version of the codec, AMBE+2, but at the lower bit rate of 2450 b/s (again not counting FEC). The consensus is that DMR sounds a bit better, but neither sounds natural and both sound worse than a good analog FM signal. One downside of building a codec into hardware is that the standard gets frozen at whatever was the state of the art when the standard was adopted. Switching to a newer standard would mean that the installed base of equipment would become obsolete. Most newer radios, including all the inexpensive DMR handhelds from China, use a software codec implementation and could in theory be upgraded, but the need for interoperability with older radio means that it does not happen. Licensing of the software from DVSI is not available, so hams experimenting with it have to use a chip implementation from DVSI (which is available as a USB dongle). Some people feel that using a commercial codec that is closed source and requires licensing is contrary?to the spirit of ham radio, and would like to see us adopt an open codec such as Codec 2, the one used in the FreeDV software. That could be done within the framework of the D-STAR or DMR protocols, but existing radios would no longer work. (The D-STAR protocol was developed by hams in Japan. The DMR protocol was developed commercially but can be used freely without licensing; it's only the voice codec that requires a license. The DMR protocol does not mandate the use of AMBE+2, but all commercial implementations use it.) There isn't a lot of digital voice on HF so the standard to use is still up in the air. FreeDV software and its associated Codec 2 are the most common, but there are also some Icom (IC-705, IC-7100) and FlexRadio models (the ones that use the newer SmartSDR software) and some hams are using that. On Sat, Aug 20, 2022 at 8:04 PM ReverendLars <lsgoodwin@...> wrote: On Sat, Aug 20, 2022 at 09:38 AM, Michael VE3WMB wrote: |
|
Re: Don't Look Back, Look Forward...FreeDV
On Sat, Aug 20, 2022 at 09:38 AM, Michael VE3WMB wrote:
Personally I have tried D-STAR on 6M with a couple of local friends (i.e. they live within a couple of miles of me) and the sound quality isn't pretty (i.e. sounds worse than C4FM and DMR)Worse than DMR?!? Oh dear. I recently picked up a TYT handheld to dabble with DMS on a local repeater system, and was NOT impressed by the sound quality. Every operator sounded like a robot, similar to the first generation of voice synthesis that debuted in the 1980s. Not unlike Stephen Hawking's famous voice! Still, the idea of chatting with DX using just a handheld is intriguing to me, so I'm not through "dabbling." But it's hard to get over that unnatural sound. Cheers es 73 de Lawrence, KC6WOG |
|
Re: Don't pre-rinse your dishes (Was: Coffee Cup)
"William Smith" said:
Unless there's egg, or oatmeal or psyllium fiber, or any number of other th=There is a difference between scraping off excessive, or difficult to clean, food waste and rinsing dishes (almost) completely clean. Contemporary dishwashers use a soil sensor to gauge when their load is clean. Rinsing dishes interferes with sensor operation. And the enzymatic detergents in common use need to have some food waste present for effective cleaning. You obviously didn't read the article. Or you're a troll. Or both. -- Steve K0STK // k0stk@... |
|
Re: Don't Look Back, Look Forward...FreeDV
On Sat, Aug 20, 2022 at 09:38 AM, Michael VE3WMB wrote:
but if the signals are strong enough there is no background noise at allall wasted effort just to compensate for that minor lack of skill: understanding the magic of those Cool Waves (CW)... :,-( Me, myself would wish a rig with an improved front-end to help me urban steel-rat survive in the qrm jungle I am forced to live in.? Ideas welcome. Not needing multi band, not needing multi mode, not even aiming for big DX. Just a couple of quiet kHz on 30 or 40m to launch one of those Cool Waves and receive a decent answer from a friendly ham would be my dream, the last dream I dare to dream... Keep going strong, yours friendly, Razvan DL2ARL |
|
Re: QSX 4th birthday !!!
#qsx
The sBitx comes either fully assembled or as a "basic kit". The latter is almost fully assembled, but you supply the Raspberry Pi, the display, and the microphone (if you want one) yourself. The basic kit is $200 cheaper, so if you have a Raspberry Pi 4 that?you bought back when you could still get them at list price it's appealing. (You can still get the display for $60 from Sparkfun.) Putting in the Pi and the display is a quick job. There is already a hardware mod on the way that replaces the linear 5V regulator with a switching buck regulator. That drastically cuts the receive power consumption from nearly 1.5A to about 500mA. (Still high for a field rig, but that's what basing it on a Raspberry Pi will do.) Exact numbers will depend on the voltage of your power supply; it will consume MORE current at lower voltages. New shipments will have the new regulator pre-installed. The mod isn't only to decrease power consumption, but also to improve the coupling of the PA transistors to the heat sink. In existing rigs, both the PA transistors and the regulator are attached to the heat sink, and the physical arrangement has been problematic because the thickness of the regulator and the transistors is not the same. Some users have blown the finals because of that. The sBitx is BIG. (Well, not big like a high end Yaecomwood, but big compared to most QRP rigs.) It's not an ideal field radio. It's also not a QRP radio (output can go all the way to 40W on 80 and 40 meters), though it can be turned down to QRP if you like. All the software is open source, which will please people who want to experiment with that. The built-in Raspberry Pi means that you can also run flDigi on it (which is used for CW decoding, among other things) and its own FT8 software alongside the SDR software. (WSJT-X will run, but it isn't designed for a display as small as the one on the sBitx so it isn't usable.) It also has a built-in contact logger. Its most direct competition is not the QSX, when and if we see that, but the T41-EP, which is not yet available as a complete kit. (4SQRP is working on that; we may or may not see it before the end of the year.) The T41-EP will be more of an actual kit because things are divided up among multiple boards (including a Teensy 4.1 microcontroller) that you have to connect. The prototype that was shown at Ozarkcon and FDIM is also large, so again it's not going to be an ideal field rig. An SDR with a display big enough to be useful is not going to be as small as a QCX-mini. But if it's designed with a flat form factor like the Elecraft KX series or the Xiegu X6100, it could have a reasonable volume and still have enough screen real estate for all that SDR goodness. Alternatively, it could compromise on the display and just concentrate on being a good radio without a big waterfall or spectrum display. I look forward to seeing what Hans comes up with. I see him concentrating on keeping the size down and making something better suited to SOTA ops and backpacking hams than the sBitx or T41-EP. Keeping the price down would also be nice; if he brings in something for under $200 (the?original target was even lower) it would be a game changer.? On Sat, Aug 20, 2022 at 12:12 AM Chris Herd <zl2tch@...> wrote: Hi All |
|
Re: Don't pre-rinse your dishes (Was: Coffee Cup)
"David Wilcox K8WPE via groups.io" said:
And those TV ads that say you don't have to pre rinse the very dirtyAccording to Consumer Reports you should not pre-rinse dishes before placing them in the dishwasher; just scrape the excess food off. Find-out the details at -- Steve K0STK // k0stk@... |
|
Re: Power Supply for QCX+
On Sat, Aug 20, 2022 at 10:19 AM, Bruce Prior wrote:
I'm working on a high school project centered around the QCX+. We need an economical 12 V power supply which is rechargeable. We need both the portable power source and an AC charger.? Any ideas?So you've never heard of 12v gel cells or wall warts. Pathetic. |
Joshua KJ7LVZ
Shirley Dulcey KE1L
Lawrence KC6WOG
Compton
Steve K0STK
DL2ARL
Tronald Dump