Re: Suggestion for the NEW UBITX V7.


I love this radio kit. While I got one of the nicest cases, still out of the case for testing, experimenting etc. 
Can not compare it to anything, as its purpose is something else.

In the way that I see it, a low cost full 80-10 radio that can be used for QRP, experimenting and learning of the circuits, and to have a lot of fun with expansions such as the touch screen, etc.

Great stuff.

On Wed, Oct 21, 2020 at 9:56 AM Bob Lunsford via <> wrote:
My son received the V6 I sent to him and told me he didn't have time to give it a thorough check out but he did check into a SSB net in Oregon from Sacramento, CA. My replacement for the V6 I sent to him is due to arrive today. I plan to use it more on the air than I did with the one I sent to my son.

Christmas is coming. $200 is not too much to spend for a gift for a ham friend or a son/daughter who may be inclined to get into ham radio. It is also an excellent Short Wave Listening receiver and who knows, once the SWLer hears some ham radio activity, his/her interests may change toward that. Just an idea.

As for a power supply, four 12V cells can be connected in series for 48V and they can be recharged individually. I'm thinking of the batteries suggested here previously (I'll have to go back to find the ones I remember that are LiOn).

Bob — KK5R

On Tuesday, October 20, 2020, 4:25:29 PM EDT, KD2QMZ <syracusepro@...> wrote:

There are 50 volts power supplies already out there for linear amplifiers and other uses. My IC-7300 cost more than 1k$ and no power supply was included.

So, let the user take care of the power supply needs as they have been doing for years.
If they want more clean power, so higher capacitance for the filters then.

As per the radio, I got V5. Didn't get the V6, but would like to see something with more power. Also, resources for the radio should be organized to guide the assembler to enhance or to provide guidance to enhance capabilities.

I love the service Farhan has given to this kits, even better than any other manufacturer, and the radio cost less than 200$.
For the amount of money, no one should expect something better then an IC-7850 or similar.

It is a great kit, great to get to learn about it, enhance and put on the air as an experimental unit.
Some do have QSO's and use it more often.

Regardless, just want to appreciate the great work Farhan has put into this, and wish something new comes out soon.


On Tue, Oct 20, 2020 at 3:42 PM Arv Evans <arvid.evans@...> wrote:

It seems that the most prevalent spurious RF problem with ham equipment is that the ham equipment uses external power.  This leads many to assume that any power supply is suitable for high sensitivity radio use.  It may not be practical to include an internal power supply inside kit radios, but we probably should include power supply specifications (voltage, ripple, spurious, minimum current capability, etc.) as part of the assembly and operating instructions, and explain what these specifications mean and how to measure them.

Hans has included some built-in test equipment inside his QCX radios.  Maybe a future version of uBITX could include use of an internal ADC based multimeter that could measure power supply voltage, current, ripple, hum, as well as outputs from a built-in Stockton Bridge type measurement for RF Power (at 50 ohms), Forward power, Reflected power, antenna impedance and possibly RF received level in microvolts & S-units.  Auto-ranging instrumentation is relatively easy to do by software observation of thresholds for ADC inputs.  Of course this would probably require a section of assembly and operation instruction that explains what all of these measurements might mean and how to use the information.

After using several versions of BITX transceiver I would heartily recommend a method for reducing power for ATU or Antenna adjustments.  

The assembly and operating manual should possibly include a section showing power supply requirements and how to measure and achieve those parameters.  Having the  above-mentioned internal measuring capability could simplify measuring things like power supply ripple, hum, and power (volts * Amps).  Desktop PC power supplies are inexpensive and easily modified to provide a solid and quiet  13.8V DC at several amperes.  Wall-warts and laptop power units are rarely suitable due to having minimal RF bypassing and an unshielded plastic case.  Linear supplies should be linear regulator units with significant over-current capability.  Remember that your power supply should have a low AC impedance furnished by RF, LF, and AF bypass capacitors.  Use a scope or fast sample-and-hold circuit to check power supplies for voltage overshoot at startup.


On Tue, Oct 20, 2020 at 12:01 AM Ashhar Farhan <farhanbox@...> wrote:
That is the scheme of hf packer : switch on the boost converter only on tx.
Another approach would be to make your radio live with noisy supplies. The best case would be to make it run off 5v supplies. They are aplenty. From PC SMPS to phone chargers to the USB power banks. It is really about time we moved to 5v standard.
A 5v supply boosted to 15v and linear regulated down to 12v could internally power the radio. The transmit would boost it to 24 or 50v. An Arduino and a low cost SMPS transformer would do the trick. If someone here as experience with this, it would be a game changer.
- f

On Tue 20 Oct, 2020, 11:12 AM Tom, wb6b, <wb6b@...> wrote:
On Mon, Oct 19, 2020 at 08:02 PM, Sila wrote:
Have you noticed any problems with the power supplies?
The one I have is a similar 12V switching supply. I puts out an RF spur that drifts across 75 meters. Fortunately, in somewhat less than 15 minutes it drifts across and away from the net I check into. 

I bought a couple of these supplier 12v 30A, 360W (was mistaken on my last post that they were 300W) to have a beefier spare supply for my 3D printer. When I bought the vintage Kenwood from a local ham I decided to try the power supply on it. I was happy it worked so well. Does have a annoying fan that sometimes starts running. Most of the lower wattage supplies do not have a fan.

Here would be a great Rube Goldberg electronic project: Put a switchable capacitor in the switching regulator circuitry to shift the frequency the supply is switching on. And depending on what frequency you are receiving on, shift the power supply frequency so the spur in not on the the frequency you are working on the radio. I'm sure adding a microprocessor would be a great addition to automating this. 

I'm not above a Rube Goldberg project once and awhile. When hard dives were new and very expensive, I programmed an 8748 microprocessor to monitor the status led on a drive that was starting to have problems booting up. When the 8748 noticed the LED was flashing a certain pattern it would pull the reset down on the hard drive and repeat this cycle until the drive would finally initialize and run. 

Got another year out of that drive. By then the replacement hard drives were higher capacity and had come down significantly in price. 

Some of the supplies I see sold for amateur radio use (from HAM radio manufactures) are switching supplies. Likely are similar supplies put in a metal box with additional RF filtering. 

For boosting the power of my uBitx, I'm still tending towards using a 12v (adjusted for 13.6v) power supply and the eBay boost converts. Only enabling the boost converters when transmitting.  I'd like to keep the main supply for my uBitx at 12V (13.6V) as that gives me more ham swap meet used power supply, battery and mobile options.

Tom, wb6b

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