Date   
Re: New tower

Dave New, N8SBE
 

You mean "stairway to heaven"?

I drive by this every day:

Cell phone tower.

It's at the Domino's world headquarters in Ann Arbor, MI, and is a 'disguise' cell phone tower.

73,

-- Dave, N8SBE

-------- Original Message --------
Subject: Re: [BITX20] New tower
From: "GM4CID" <gm4cid@...>
Date: Tue, December 17, 2019 9:15 am
To: BITX20@groups.io

Makes me think of the Led Zepplin song.

Re: µBITX & QRP labs 50W PA

ajparent1/kb1gmx
 

Mark,

For SSB high idle current are not a factor (unless unrealistically high) as
the average current is likely going to be higher and if heat is an issue
than larger heatsinks or fans are the solution.

Keep in mind speculation is not measurements.  For 50W out 
your input DC at 20V has to be in the range of 70 to 90W
assuming 70 to 50% efficiency.  The difference between output
power and input power is resulting in heat.  Power amplifiers 
above the milliwatt range are all concerned with heat and
managing it.

I have used the same heatsinks for the QRPLabs 10W SSB amp 
at higher voltages and power there is a lot of heatsink there.  Running
bias in the 100Ma per device range is fairly trivial at 4W.  Even at 250ma
we are at under 10W.    Considering at 50W out the likely current  is
3.6A at 20V and converting 30% of that to heat for classC and much
Less (typical is 55%, average) for class AB1.

For SSB running to 50W peak the average is likely closer to 20W
and the heat load is maybe near 20W average as well assuming
50% efficient and that would be low.  So heat should not be an issue
with supplied heatsinks and reasonable airflow (no sealed chassis)
and not over driven.

It should be noted that for SSB the peak power is around 50W the
average will be lower and should be to avoid splatter from clipping.
That means the SSB drive power should be lower than CW.

Allison
---------------------------------
No direct email, it goes to bit bucket due spam

Re: µBITX & QRP labs 50W PA

Gordon Gibby
 

Allison, great information!   That sheds a great deal of light on the subject, thanks!


On Tue, Dec 17, 2019 at 11:26 AM ajparent1/kb1gmx <kb1gmx@...> wrote:
Since I run an EBY amp since 2006 you must have mis-read.  In the files section
I've even posted his articles back around 2010 and copied to this iteration years
ago. Still there.

The ubitx is not run that low, spec is 100ma per. 

The irf510 like all fets has a considerable hook at low gate to source voltages.
If the gate voltage is platted against the drian current the linear window is above
100ma and below saturation or about 4A.  Below that in the low end under 100ma 
drain current he gate voltage is not linear at all from start of conduction to the 
100ma range and  that makes for very non linear near cross over.  Class AB1
is more like 80-150ma but it is very toplology dependent.

His (WA2EBY) minimum was 50 ma per device for CW and testing put it higher
near 100ma per device for SSB to get a decent IMD at 28V.  I find mine
comfortable at 125 ma per device and the two tone testing is good enough at
about -28dbc.  However that design has the features needed for linear operation
including independent device bias,  current sourcing transformer for the drains
and large ferrite for the output transformer.

At 100ma per you only talking a standing power of 2.8W at 28V per device,
if that gets warm the heatsink is inadequate. 

So saying a specific current, especially low under 100ma, is inadequate
for linear use without testing questionable.  Especially for an amp designed
for class C use.  I do not say it cant be linear but at low bias its highly unlikely.

I have one on the way so testing will happen.

Allison

--
---------------------------------
No direct email, it goes to bit bucket due spam

Re: µBITX & QRP labs 50W PA

ajparent1/kb1gmx
 

Since I run an EBY amp since 2006 you must have mis-read.  In the files section
I've even posted his articles back around 2010 and copied to this iteration years
ago. Still there.

The ubitx is not run that low, spec is 100ma per. 

The irf510 like all fets has a considerable hook at low gate to source voltages.
If the gate voltage is platted against the drian current the linear window is above
100ma and below saturation or about 4A.  Below that in the low end under 100ma 
drain current he gate voltage is not linear at all from start of conduction to the 
100ma range and  that makes for very non linear near cross over.  Class AB1
is more like 80-150ma but it is very toplology dependent.

His (WA2EBY) minimum was 50 ma per device for CW and testing put it higher
near 100ma per device for SSB to get a decent IMD at 28V.  I find mine
comfortable at 125 ma per device and the two tone testing is good enough at
about -28dbc.  However that design has the features needed for linear operation
including independent device bias,  current sourcing transformer for the drains
and large ferrite for the output transformer.

At 100ma per you only talking a standing power of 2.8W at 28V per device,
if that gets warm the heatsink is inadequate. 

So saying a specific current, especially low under 100ma, is inadequate
for linear use without testing questionable.  Especially for an amp designed
for class C use.  I do not say it cant be linear but at low bias its highly unlikely.

I have one on the way so testing will happen.

Allison

--
---------------------------------
No direct email, it goes to bit bucket due spam

Re: µBITX & QRP labs 50W PA

 

Hi,

I think linearity will depend on a lot of things, most importantly supplied voltage and bias current (and likely input signal level as well).   I would think it would also depend on the design of the amplifier and not only on what output device it uses.

In WA2EBY's article, he doesn't show or talk about any linearity measurements that he might have made, only that "No indications of instability, CW key clicks or distortion on SSB have been reported." which is not really a reliable test.

So I would either say as Jerry does and have a way to measure IMD distortion, or go with what the designer recommends.  For SSB, unless you are really long-winded, is it probably is OK to have higher idle currents; 250mA at 20V is only an idle of 5W so not so bad if the heatsink is good for intermittant 50W.  Regardless, it would be nice to see some test results showing IMD versus idle current so it could be set it as low as it can. 

73,


Mark.




Re: Templates for China EF01 Electronic Plastic Shell Project Case for a BITX40

KE2GKB
 

Thingiverse has quite a few front panels for this as well available as models that can be 3d printed. they work quite well
as an example but there are quite a few!


On Tue, Dec 17, 2019 at 9:27 AM <pluto@...> wrote:
I I bought this case (S06A): https://www.aliexpress.com/item/4000284522671.html
It is not a real bargain but it comes complete with useful accessories

Cheers,
Diego I8TIF


--
Tim Keller - KE2GKB
https://shop.kit-projects.com

Re: [GCBG] HF Coupon for case

Jack, W8TEE
 

Yeah, I didn't notice the fine print as I was buying a gift for my son. Sorry about that.

Jack, W8TEE

On Tuesday, December 17, 2019, 9:46:59 AM EST, <kd8vrx@...> wrote:


$5 is a steal but the fine prints says "only available with qualifying $49.99 minimum purchase".  Most of us can find a way to spend that much, there's always something you can use/need.  I have a few of these cases and they are very good, the MFJ Analyser will also fit in one of those, which is perfect for field day.

Jocelyn
KD8VRX

--
Jack, W8TEE

Re: Templates for China EF01 Electronic Plastic Shell Project Case for a BITX40

pluto@...
 

I I bought this case (S06A): https://www.aliexpress.com/item/4000284522671.html
It is not a real bargain but it comes complete with useful accessories

Cheers,
Diego I8TIF

Re: Templates for China EF01 Electronic Plastic Shell Project Case for a BITX40

GM4CID
 

You could mock up front and rear panels on stiff card, easy to make changes and when you are happy use as your front and rear templates.

Re: µBITX & QRP labs 50W PA

padmanabhan cattamanchi
 

Most of the the VU2s use a laptop smps with a bit of filtering to give nearly 20 watts out. I don't think there is a need of another amp since the devices are the same

de vu2pep 

On Tuesday, December 17, 2019, 05:28:23 PM GMT+5:30, John AE5X <ae5x@...> wrote:


At $300 the HR-50 supports the uBITX on all bands and modes. And it does not require a PTT In signal since it has a carrier-operated relay:
https://www.hobbypcb.com/index.php/products/hf-radio/hardrock-50-hf-power-amp

John AE5X

Re: New tower

GM4CID
 

Makes me think of the Led Zepplin song.

Re: HF Coupon for case

Jack, W8TEE
 

Ken:

I didn't notice that as I used it when I bought my son a Christmas gift. Still, it's a pretty good deal.

Jack, W8TEE

On Tuesday, December 17, 2019, 9:12:30 AM EST, Ken Hansen <ken@...> wrote:


That $5 price is after an additional $49.95 purchase. I agree, it is a great little case - I use one to hold a DMR HT, Pi-Star hotspot, USB battery pack for both, and a charger as a mini DMR go-box 'solution' - just add wifi and you're one the air' (so to speak).

Ken, N2VIP

On Dec 17, 2019, at 08:05, Jack, W8TEE via Groups.Io <jjpurdum@...> wrote:


All:

Harbor Freight has this coupon:

<hfCoupon.jpg>


for the small Apache case. It's regular price is $15 and often on sale for $10, but $5 is the cheapest I've seen it. I put Diz's 5 W in one:

<FigureJ(Small).jpg>

and it worked out well. I put all the connectors on the top panel so it remains watertight and still has room for paddles, earbuds, and antenna.

Jack, W8TEE


--
Jack, W8TEE
<hfCoupon.jpg>
<FigureJ(Small).jpg>
<hfCoupon.jpg>

--
Jack, W8TEE

Re: HF Coupon for case

Ken Hansen
 

That $5 price is after an additional $49.95 purchase. I agree, it is a great little case - I use one to hold a DMR HT, Pi-Star hotspot, USB battery pack for both, and a charger as a mini DMR go-box 'solution' - just add wifi and you're one the air' (so to speak).

Ken, N2VIP

On Dec 17, 2019, at 08:05, Jack, W8TEE via Groups.Io <jjpurdum@...> wrote:


All:

Harbor Freight has this coupon:

<hfCoupon.jpg>


for the small Apache case. It's regular price is $15 and often on sale for $10, but $5 is the cheapest I've seen it. I put Diz's 5 W in one:

<FigureJ(Small).jpg>

and it worked out well. I put all the connectors on the top panel so it remains watertight and still has room for paddles, earbuds, and antenna.

Jack, W8TEE


--
Jack, W8TEE
<hfCoupon.jpg>
<FigureJ(Small).jpg>
<hfCoupon.jpg>

HF Coupon for case

Jack, W8TEE
 

All:

Harbor Freight has this coupon:

Inline image

for the small Apache case. It's regular price is $15 and often on sale for $10, but $5 is the cheapest I've seen it. I put Diz's 5 W in one:

Inline image

and it worked out well. I put all the connectors on the top panel so it remains watertight and still has room for paddles, earbuds, and antenna.

Jack, W8TEE


--
Jack, W8TEE

New tower

Jack, W8TEE
 

...and my kids didn't think I could put it up myself!

Inline image


--
Jack, W8TEE

Re: Templates for China EF01 Electronic Plastic Shell Project Case for a BITX40

Mike Short
 

I used some PCB for mine. Or you can go to a hardware store and get some aluminum and make a new panel. The steel one is hard to work with. 


mike
AI4NS

Re: µBITX & QRP labs 50W PA

John AE5X <ae5x@...>
 

At $300 the HR-50 supports the uBITX on all bands and modes. And it does not require a PTT In signal since it has a carrier-operated relay:
https://www.hobbypcb.com/index.php/products/hf-radio/hardrock-50-hf-power-amp

John AE5X

Re: uBitx FT8

Ashhar Farhan
 

By August, we didn't have any v4 boards. Can you send me a picture directly to my email address?
- f

On Tue 17 Dec, 2019, 1:48 AM V Zecchinelli, <n1vin@...> wrote:
Jerry, Sarma, Gordon,

Wow, am I confused.  I purchased 12 August 2019 and I thought it was a V5 however after Jerry's response I looked and it is a V4.  My bad for not checking things better.  Live and learn.

I am using a stereo cable I bought on ebay cheap.  After your responses I decided to check the 3.5mm connectors to see if there could be a short there.  Well, there are only 2 wires in the cable and shield and ring are connected together.  Lesson, don't buy cheap cables on ebay.  I will order some quality stereo cables from Amazon and see how things go.

Thank you so much for your responses.

Vince


On 12/16/2019 12:46 PM, Gordon Gibby wrote:
Are you DC shorting out the output with a transformer in the sound card??


On Dec 16, 2019, at 12:07, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

I'd guess your USB soundcard cabling is somehow (almost) shorting out the audio from that 2822 chip.
Look for a short.
Perhaps add an 8 or 10 ohm resistor in series with the TDA2822 to protect it from shorts like that.

The TDA2822 amp was used on v3.
Some discrete transistors were used on v4.
On v5, as Sarma has stated, the trusty (crusty?) old LM386 was used.

If you have a TDA2822 chip installed, it is probably v3.
A search of the forum for 2822 will reveal that a few v3 uBitx boards went out
with a WX branded TDA2822.  This clone of the TDA2822 works fine up to about 8v,
above 8v it can sometimes self destruct.   If you have a WX branded TDA2822 on
your board, I suggest you get an NJM2073D ordered from a reputable distributor
It is pin compatible with the TDA2822, works fine, good to 15v or so.

The original TDA2822 in the DIP package from ST is no longer available,
though ST does still sell it in an SOIC.
There are a half dozen different makers of clone TDA2822's, many of them work fine.

Some of the clones work ok but only with a maximum supply voltage of around 6v.
With the WX TDA2822 clone operating at 12v in the uBitx, the chip might work fine
for weeks and then suddenly decide to blow bits of silicon across the room.


A fun bit of trivia from https://en.wikipedia.org/wiki/LM386
  "The LM386 was invented by Ernie Leroy Long at Motorola in 1969. It was originally for part of a fuel injection system for a Ford Car."

If true, I assume it went by a different name at the time.
I'm a bit suspicious, a google for "LM386 Ernie" gets many copies of exactly the above phrase with no further information or attribution.
The "LM" prefix suggests National Semiconductor, perhaps it had a different name coming out of Motorola.

Jerry, KE7ER
 

On Mon, Dec 16, 2019 at 07:10 AM, V Zecchinelli wrote:

Good Morning,

I have a quick question on FT8 with uBitx V5 using USB soundcard (7.1 Channel).  Even with the volume of uBitx set very low the 2822 audio amp gets very hot and if volume set over 1/4 it will fail catastrophically.  On phone I can listen to the radio all day with no issues.  Seems odd.  Anyone else seen this problem?

Thanks,
Vince

Re: µBITX & QRP labs 50W PA

Ashhar Farhan
 


Allison,
I am basing my report in wa2eby's recommendations. My own measurement lead me to believe that between 25 ma to 150 ma, there is not much of a difference in linearity. The linearity increases only around 500ma. By then, we are roasting potatoes.

- f

On Tue 17 Dec, 2019, 3:22 AM ajparent1/kb1gmx, <kb1gmx@...> wrote:
Farhan,

No its not.  You need to be more than 100ma to get sorta on the linear part of the IRF510 bias curves.

At minimum bias you are on the very curved part of the gate threshold curve and the IMD will be poor with
crossover distortion.  Also we are not switching as its linear from transistor to transistor its complementary.
 
---------------------------------
No direct email, it goes to bit bucket due to spam

Re: Brand new uBiTX v5.0 quality issue ?

pluto@...
 

Hi Ashhar, I agree with you.
I also wrote a serious email to hfsignals attaching several photos but they haven't given me any answer yet..

73's Diego