Re: Collector current design point for Q911+Q912?

Jim

What's this "SSB" you speak of?  ;)

Note that I am not asking the original question as a way to "hot rod" the output of the uBitx V6, but rather as an approach to level off the output power with increasing frequency, as per Allison's suggestions.  Once I'm satisfied, I'll back RV1 off so that I'm getting at least 5W out on 20m, and the rest can fall wherever.

QRP CW op (mostly) here, so I understand the ability to get a signal out at 5W or less.

Thanks all.

Re: Collector current design point for Q911+Q912?

Curt

Jim

before you do all of that - have you measured both the CW and SSB output levels into a 50 ohm load?  yes you will need some kind of audio oscillator, but this might provide a little further insight.

also consider how you might use a few-watt rig in the SSB mode?  certainly as solar flux is higher, it might cross oceans but I am thinking on the upper bands.

we have a tendency to overvalue watts over dB's.

Curt

Re: Collector current design point for Q911+Q912?

Jerry Gaffke

Here's how calculate the quiescent current, so no signal present:
For DC, T9 is just a piece of wire, and the 2.2 ohms at R89 is small enough to be disregarded.
So we have 12v across R85,R86, and the current through those resistors is 12v/(100+1000) = 0.011 Amps
and the voltage across R85 is  100*0.0109 = 1.1 volts.
We're assuming that the beta of the transistors is high enough that the base current can
be ignored.  Let's also assume that the voltage drop from base to emitter when in the active
region is around 0.7 volts (the BE junction looks like a silicon diode),
so the emitter voltage is 1.1-0.7 = 0.4 volts.
Each 22 ohm emitter resistor at R87, R88 has  0.4v/22ohms =  0.018 Amps through it.
And since the base current is so low, that is also the collector current.

Jerry, KE7ER

On Mon, Feb 10, 2020 at 07:46 AM, Jim wrote:
Hi Mark -- I plan on doing that (needing three hands and a prehensile tail), but also wanted to know what the intended value was so I know the difference between design and application here.

Re: Collector current design point for Q911+Q912?

Jim

Hi Mark -- I plan on doing that (needing three hands and a prehensile tail), but also wanted to know what the intended value was so I know the difference between design and application here.

Thanks!

Re: Collector current design point for Q911+Q912?

Hi Jim,

You can also check the voltage drop across the emitter resistor during transmission and then you can calculate the current used.

73,

Mark

Re: Collector current design point for Q911+Q912?

Hi,

From datasheet max is 400mA.

Re: How Come?

No boot intended :-)

I think the main thing is that ubitx.net is a very helpful site, and it would be nice to make a more obvious link to is somewhere.

And members might want to visit the actual group website sometimes and explore all the sections.

73,

Mark

Re: Made Mods to V3 uBitx - no longer transmitting

Steve - KE0VCD

Thanks Curt,

It appears to be a 4.7k resistor.

From the instructions:

"The CW keyer has to be wired even if you don’t intend to use CW. Yes, the 4.7K resistor to 5v is a must."

Collector current design point for Q911+Q912?

Jim

Just what the title says -- what's the design point for the combined collector current going to Q911+Q912?  Looking to sub in a 2N5179 here, but only has a max collector current value of 50 mA.

Thanks, Jim KK0U

Re: SpecturmLab visual audio clueless

Don - KM4UDX

Evan -- I adjusted the SSB per guidance, then went all the way to 6000. What a daring dude!

The freq spectrum shifted south as expected.

I've been advised that the initial audio was actually good enough. So it is likely I've made things worse with these Delta's. Hahaha.

I'm going to try a on-line SDR site recorder so I can hear for myself.  I'm also getting a new mic.  So my pill bottle mic will be retired to museum status.

Thanks to Dean KK4DAS as well for his wonderful help

Re: Revisiting lower power output on 40m, V6

Jim

Ok, so I removed C81 and subbed in a couple of other value capacitors with no real joy.  I finally subbed in a 0.01uF and now have this:

80m: 12.2W

40m:  10.6W

30m:  7.6W

20m:  4.0W

17m:  3.1W

15m:  1.6W

10m: 0.6W

*This* I can deal with, as it looks like what I would expect. I have some 2N5179, 2N3866A and 2N3553 in the junk box that I can sub in for the rest of the amplifier chain before the finals to help raise the upper end a wee bit. Off to a new thread! (Yes, I've read all the threads about transistor substitution in the predriver and driver circuits).

Re: How Come?

David Wilcox <Djwilcox01@...>

I thought I had looked at all those links when I started down this rabbit hole a few years ago.  Sorry, my wife (my right seat pilot) doesn’t look over my shoulder when I am reading ham radio emails. Thanks for the soft boot to the hiney.

Dave K8WPE

On Feb 9, 2020, at 11:37 PM, Mark - N7EKU <n7eku@...> wrote:

﻿Hi,

Look on the left -> click on "Database" -> click on "Links"   Group members can add more links as they want (it's not been updated for awhile I think)

It's not an obvious place for the links, but I don't think groups.io lets you add new page categories on the left.  Moderators would have to answer that.

I guess someone could go to the Wiki page too and add a links section there too if they want.

73,

Mark

Re: new nextion 5/7 hmi bug

Mark Hatch

Richard,

That does not look like the screens that Joe and I worked on. (it does look like a Nice improvement!)

What is the problem?

73
mark
AJ6cu

Re: Anyone used the ELEKITSORPARTS digital interface board? Opionons?

Evan Hand

dwhacks,

I had to look really close to see the mod.  Good job on the soldering, not sure that I could make it even close to that clean.

As long as it is working, I would not change it back.  From what you said before you have enough signal to the PC and do not need the amp.

73
Evan
AC9TU

Re: How Come?

Hi,

Look on the left -> click on "Database" -> click on "Links"   Group members can add more links as they want (it's not been updated for awhile I think)

It's not an obvious place for the links, but I don't think groups.io lets you add new page categories on the left.  Moderators would have to answer that.

I guess someone could go to the Wiki page too and add a links section there too if they want.

73,

Mark

Re: Anyone used the ELEKITSORPARTS digital interface board? Opionons?

dwhacks

Thanks for the insight and link. I will look into it as that was my assumption as well. It made just as much noise without it connected to the ubitx so maybe the 5v for the amplifier is from USB. here’s a picture of what I’ve done.

Re: How Come?

Vince Vielhaber

Apparently so. I just looked thru the group on groups.io and don't even see a Links section, not sure why we don't have one.

Vince - K8ZW.

On 02/09/2020 07:19 PM, AndyH wrote:
Footers. I guess that's for the folks that consume the group via
individual emails?

On Sun, Feb 9, 2020 at 05:10 PM, Vince Vielhaber wrote:

Dave, if you look at the footer of every message there are a number of
links. ubitx.net is the 5th one or second from the bottom.
Vince - K8ZW.

On 02/09/2020 06:51 AM, David Wilcox via Groups.Io wrote:

How come I never saw any reference to this site before and I
all the uBitx emails and joined github just to keep up for the day I
would finally get the courage to jump in and tinker with one?

https://ubitx.net/category/hardware/display/

I finally picked up at HamCation a working version 3 with the
Nextion
color/touch screen and other mods and started looking around (thanks
Safari) for more than the base hfsigs site and the above site
came up.
A wealth of mods all in one place with good details and
explanations.
Even Pete’s list of mods.....

Thanks to all who make this site, the .io group emails and github
happen. This old dog just may learn a new trick or two.

Dave K8WPE

--

Re: How Come?

Hi,

I've seen the site mentioned many times in posts.  I actually can't figure out how you've missed it.  A search of the messages for the term results in almost 600 mentions in the posts!

73,

Mark

Re: new nextion 5/7 hmi bug

Richard E Neese <r.neese@...>

the math in the tmp1 file on the vfo page

Re: new nextion 5/7 hmi bug

Richard E Neese <r.neese@...>

its the math for the dsp display on the vfo page