Thank you...Jan 18 is getting closer!? My 7 and 9 year old helpers are getting eager to "talk to someone" and not just lookup WSPR spots on the globe.? Sadly, my 12yr old asked "do you 3 really think that is fun?"

Rob
AG5OV

Not yet, I have decided to re-model the case, and install my RaduinoI2C board... Also mounted a swr bridge... Gonna be a nice little rig if I get reasonable results from the PA mod..
73..

Good thought, Marco.

But most. if not all variable VR's have a fixed or lesser
VA output. IF you lower the voltage, usually the available
amperage goes down as well...

I use two in my bench supply, one with a 7815 and one
with a LM338. They work well to provide a variable voltae
but the available current is not 5A (say) for the LM338
unless the voltage is quite high. At very low voltages,
the available current is 0.5A or less.

But it is a good thought. Possibly it could be rigged
as a linear supply with 2 LM338's and a LM324 regulator...

It would be cheaper than buying separate fixed supplies.
Also cheap are variable shunt and digital supplies, but
they usually have a big RF noise problem and require
some hefty filtering..

john
AD5YE

Shaun,

The ubitx doesn't have a balanced mic input, i.e. mic leads that don't
have one connected directly to system ground. In a balanced feed the
shield wire would be the system ground and would act as a shield to both
mic wires. Ideally in such a case the PTT would probably also have two
leads, a plus and minus, although many times the shield is just used as
the ground lead.

The PTT shouldn't be wired serially with the mic, both just use a
common ground. When the PTT is pushed the PTT switch closes the PTT
lead to the shield, i.e. system ground. At the same time the mic lead
from the element is connected to the mic lead in the cable. The minus
mic lead is connected solidly to the shield, i.e. system ground.

If the ubitx ran more power it might be necessary to take more care
with the mic circuitry. At 10-15 watts it just isn't necessary as long
as the wires inside the cabinet are dressed properly and kept away from
the PA section of the circuit board.

If you'll download the operating manual for the ftdx-3000 from the
Yaesu site and look at the page with the connector wiring, you'll see
on the microphone connector that there are two mic leads that are
separate from system shield. In fact there is even a totally separate 5v
lead for powering an electret element. Yaesu expects there to be a
blocking capacitor on the mic lead to isolate the 5v from the radio mic
circuit.

tim ab0wr


On Fri, 9 Mar 2018 18:04:27 -0600
"Shaun" <slong682000@...> wrote:

" If you tear a lot of communication mics apart you will see that the
mic element is wired through the PTT switch on most of them."

That is exactly what I would expect and have seen in the past, but
again, the mic wire up I saw on an earlier post for an older version
did have the PTT as a separate circuit, not wired serially with the
electret. While it doesn't address the mic wire up specifically, the
wiring diagram for the uBITX from the website seems to suggest the
same, PTT and mic are two separate circuits. I think you have
confirmed my original way of thinking of how I should wire it up,
i.e. closure of the PTT switch applying ground to the MIC- side of
the electret, and is the way I will go. I am using an old HT
spkr\mic and going that route just means I need to move one
connection point internally and I'm where I need to be. Thank you for
the assist, Tim

Shaun
KE?NLN

On Fri, Mar 9, 2018 at 3:14 PM, Tim Gorman <tgorman2@...> wrote:

Jerry,

Having a live mic with a separate, unassociated PTT switch can lead
to inadvertent transmissions if the PTT gets operated accidentally.
If the mic is not live all the time then all you transmit on an
accidental PTT operation is a suppressed carrier which hopefully
won't bother anyone.

It doesn't happen a lot but it *does* happen. Someone accidentally
pushes his foot switch with a live mic and sends out a discussion
with the wife (spouse) over the air.

Admittedly you can butt transmit with a PTT CB mic or 2-meter ham
mic if you sit on it. It happens also.

For me, the switch is there in the mic and I don't see any reason
not to use it. If you tear a lot of communication mics apart you
will see that the mic element is wired through the PTT switch on
most of them. Apparently someone thinks its a good idea!

tim ab0wr

On Fri, 09 Mar 2018 07:54:26 -0800
"Jerry Gaffke via Groups.Io" <jgaffke@...> wrote:

How is this an advantage?

On Fri, Mar 9, 2018 at 07:23 am, Tim Gorman wrote:

The mic is only actually connected when the PTT switch is
pushed. .... This is why I recommend using a communications
mike instead of a standalone mic with a separate PTT switch.

Works...


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Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
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email: bill@...

This is the modification I came up with to implement a 7805 to supply the TDA2822.

Please check it over for errors.? One trace cut and scrape a little off the board and solder in the 7805.

Ron W7HD

--
W7HD - NAQCC#7587 OMISS#9898 KX3#6966 LinuxUser#415320

I received my uBitx today

ordered January 8, 2018
notice of being shipped March 6, 2018
received March 9, 2018

john kg9dk

开云体育

Pete,

Maybe some more experimentation with the capacitor value is needed. The diode has some finite forward resistance so it will take some small amount of time for the cap to charge up. I originally had the circuit connected to U1 input as well and had settled by experiment on 330 nF. Didn't see any change in effectiveness when I moved it to M2. So maybe a somewhat smaller capacitor will fix it. (Don't remember what I have for the resistor, btw). Also by the way, my gate circuit is slightly different. I have only the diode in series with the T/R signal going to the gate. Both the capacitor and resistor are connected from the gate to ground. I seem to remember that I had a hard time getting it to work until I tried it this way. Don't know what difference it might make, though.

For R70, I knew I wanted something larger than 10 ohms to have the voltage divider produce enough output, but not so large that the maximum volume available from the volume pot would be reduced significantly. I saw that I had the 510 ohm part and thought, "try this". Simple as that.

73, John

Thank John, moving the Drain to R70 (changed to 510) helped restore my volume. However, I am getting the pop going key down RX to TX but no pop going from TX to RX.
So the MOSFET is not muting quite fast enough.?

How did you determine the value you used for R70??

Pete WK8S

Thanks Ian. For a great updated to include WSPR, It was a surprise.

Philip G7JUR.

Walter,

What voltage are you feeding this with? I assume it is more than
24v in order for you to have a 24v position.

If you are running in the 10 volt position, for instance, that would be
drop of at least 24v - 10v = 14v. Fourteen volts at .5amp is 7W being
dropped into that transistor. That's a pretty fair amount of heat.

tim ab0wr

On Fri, 09 Mar 2018 06:17:16 -0800
"Walter" <W9KJO@...> wrote:

On Wed, Feb 21, 2018 at 06:23 pm, LKNDAVE wrote:

i did the hokie pokie and this jpg came out

Based on this design I built this attached circuit.

It controls voltage nicely.? Really helps limit output power while
working digital.

However the TIP 142 really generates some heat.? I have a heat sink
on it but it will need to be much larger.? it is only drawing
about .5 amp (1/2 amp) while transmitting.

Does that seem normal?? it the heat something I should be concerned
about?? Or just provide a better heat sink and run it?

Thanks for the circuit idea and plan.
?
--
73, W9KJO
Walter

Jerry,

Having a live mic with a separate, unassociated PTT switch can lead to
inadvertent transmissions if the PTT gets operated accidentally. If the
mic is not live all the time then all you transmit on an accidental PTT
operation is a suppressed carrier which hopefully won't bother anyone.

It doesn't happen a lot but it *does* happen. Someone accidentally
pushes his foot switch with a live mic and sends out a discussion with
the wife (spouse) over the air.

Admittedly you can butt transmit with a PTT CB mic or 2-meter ham mic
if you sit on it. It happens also.

For me, the switch is there in the mic and I don't see any reason not
to use it. If you tear a lot of communication mics apart you will see
that the mic element is wired through the PTT switch on most of them.
Apparently someone thinks its a good idea!

tim ab0wr

On Fri, 09 Mar 2018 07:54:26 -0800
"Jerry Gaffke via Groups.Io" <jgaffke@...> wrote:

How is this an advantage?

On Fri, Mar 9, 2018 at 07:23 am, Tim Gorman wrote:

The mic is only actually connected when the PTT switch is
pushed. ....? ?This is why I recommend using a communications mike
instead of a standalone mic with a separate PTT switch.

whats the latest on the new w8tee lcd vfo for the ubitx ?

Here's a starting point on web resources regarding this big/little endian stuff in case you're curious.
? ??

But for most of us this is a non-issue, and you needn't worry about it.
And you certainly don't have to suffer anybody arguing about it.

Code on the Nano (and likely in most any Arduino environment) is little endian.
Though on an 8 bit machine like the Nano, endian-ness is mostly a matter of what the compiler wants to do.
? ??
? ??

Jerry, KE7ER

I found a much better place to connect the drain of the MOSFET. First I replaced R70 with a 510 ohm resistor that I happened to have in the same footprint.

Then I connected the MOSFET drain to the relay side of that resistor, i.e. to the point M2 on the schematic. This setup still shorts the incoming audio to ground and kills the pops, but leaves a voltage divider of R253 and R70 connecting the sidetone to the volume control. Depending on your value of R253, this may be perfect as is. My R253 was 220 k and I needed more volume, so I put a 50 k trimpot across R253. It is just about right for me at maximum resistance, but I can adjust it downward if I should want more volume still. If your R253 is a smaller value and the sidetone is too loud, just replace it with something of higher resistance.

The volume control will now have final control over the level and can be tweaked in operation if needed.

73,
John AD0RW

Mods so far, in tested.?

--