Date   
Re: CQ tonight

doghouse3@...
 

Unfortunately I get the single email with all the updates and it comes the next day. Would you be able to post a day ahead of time when you will be on. We just finished out BitX40 day before yesterday and would love to listen to you. Thanks, Joy

Re: W8TEE TFT/ VFO DISPLAY BOARD BOARD

Art Olson
 

Jack

I must have missed this in the build or setup. The voltage continues to change so it must be floating. I have the tft/vfo connected to the bitx40 power so don't think I have a ground problem. Could you resend the detail about the voltage divider 

"If you connect the display voltage pin to your voltage source, it will flash one or two times at power up, but will only update itself if there is a measurable change in the supply voltage. My guess is that you don't have yours tied to either ground or a voltage divider. As a result, the pin is floating which is read as a new voltage which triggers a screen update.I had mine running several hours last night and it never varied enough to update the field". 

art

Re: CQ tonight

David Woodward
 

it would be convenient if we had an echolink node just for real- time bitx contacts and troubleshooting....

On Jul 15, 2017 4:48 PM, <doghouse3@...> wrote:
Unfortunately I get the single email with all the updates and it comes the next day. Would you be able to post a day ahead of time when you will be on. We just finished out BitX40 day before yesterday and would love to listen to you. Thanks, Joy

Re: On the subject of fake IRF510

John Backo
 

Rich got it right.

These devices were originally intended for low frequency switching; they can
handle large currents, but only for a very short time. Their use at RF DEPENDS on
finding a very small gate voltage area which allows linear operation.
Sometimes that area does not exist, even on the originals and true copies.

Some later ones were especially designed for use at RF. They are not MOSFET
switching transistors.

So using a IRF MOSFET is always a case of possible pig in a poke. Some of
them will not work no matter what one does to them. Fortunately, most will work,
but tuning the gate voltage is absolutely critical. At around 5v, there is a sudden release
of ALL available current at the drain to the source. This is the so-called "avalanche" condition.
It must be avoided at all times if using the device for RF (which means that it is harder to
use them when a full-time carrier is involved -- but it van be done).

The other major consideration is the heat generated. These MOSFETS have very poor heat transfer
characteristics. And there is a very small die area where the "switching' work is done. Heat transfer
must be maximized and strictly controlled. Else, poof! There it goes (in milliseconds). It also
very easily breaks into oscillation, especially VHF oscillation. That is controlled by impedance matching of
the drain to the output.

The best tuning is to set the gate voltage low (2v?) without a drain connection. Then connect the
drain supply. Then slowly increase the gate voltage until a SMALL current increase is seen in the drain.
That is getting as close to the linear region as one is able to do with these devices. This is true
(and a characteristic) of all switching MOSFETS. (The major differences are in the peak voltage, the current
each can handle, and the gate capacitances; these vary tremendously according to their die arrangement).
Then connect and adjust your RF source to the drive transistor...this is also just about the recommended procedure
for the BITX40.

These devices work much better at voltages higher than 12v. Those especially designed
for RF use (like the RDHHFxx) devices ARE designed to be used at 12v. Not true for switching MOSFETS.
The RF devices are also much more expensive, but they are more or less guaranteed to work at HF.

There are a few, like the 2N3555, which were in use very early. They are sort of bastard devices with sometimes
good and sometimes bad characteristics. Note that the 2N3555 is really a MOS clone of the 2N3055, a NPN
ordinary transistor. The 2N3055 gained fame as an output transistor in linear power supplies. This was designed
as a MOS replacement, which in fact does run cooler than the original. Doug Demaw was an early investigator of these
devices, and he noted very early on their "odd" characteristics. When the IRF devices first came out, it was
discovered that they could be used as RF devices (much to the design engineers' surprise), but with all the
caveats noted above.

Incidentally, that Hackaday post is a copy of the one he put on his blog. It, and more, are available in full there.

john
AD5YE

BITX echolink node

David Woodward
 

While this is a great group with many capable people, it is way too slow in response time.
 Wouldn't an echolink node strictly for bitx related things be more convenient? 
 What are your thoughts?

Re: W8TEE TFT/ VFO DISPLAY BOARD BOARD

John Backo
 

Good thought, Mike.

I think what happened is that a huge quantity of these devices were
made, and a certain quantity of them were shipped with iffy crystal oscillators.
They became part of the mix and were sold sort of as-is.

Then it was discovered that many, if not all, of the output filters were wrongly
configured. That caused all of them to be dumped on the open market.
For a time, they were freely available and cheap. Then, when the demand
was verified and supply ran out, a new batch was made which are currently for sale
(and more expensive). These newer ones should have better quality...but I wonder.

It is easy to operated the 3.3v oscillators at 5v. It changes the frequency a bit,
but not much else. However, it does put a strain on them and they can fail early.
You can also usually operate the 5v units at 3.3v. Mostly, they oscillate at about
the right frequency. I would suppose they last somewhat longer, but I have not verified that.
Proper oscillators are easily available (now) and replacement is easy. So there is no real
problem, I guess.

john
AD5YE

Re: I don't believe it!

Dexter N Muir
 

Thanks, Bill.  Yes, even night-time seems to be dead here in NZ. Tuning to the zero of what I take to be those SW-BC stations, I ought to hear voices/music, them being AM, right? Sorry, nothing. I've heard an occasional CW down the bottom of the band, but *only* occasionally, and my CW skills are truly rusty! Yes, it's all coming in by the antenna - total quiet when unplugged, as expected. I might be able to inveigle a local to 'beacon' for me by a call on the local repeater - that might be worth a try.

Re: On the subject of fake IRF510

Jerry Gaffke
 

I find this post from Allison to be informative, she definitely knows what she's doing:  
    https://groups.io/g/BITX20/message/22597 

There are issues with the IRF510 as an RF amp.
Primary issue is poor thermal conductivity from die to TO-220 tab.
Also, the tab is connected to the drain, not the source as it would be in a good RF device,
so be careful not to short the heatsink to ground!  (Or add a $0.05 mica insulator and heatsink paste.)  
The IRF510 does work better at 24v than at 12v, giving better linearity.

But otherwise, Allison reports that the IRF510's  behavior is similar to
the 10x more expensive RF devices such as the RD16HHF1.
She continues to use the IRF510.

Jerry, KE7ER



On Sat, Jul 15, 2017 at 02:45 pm, John Backo wrote:
using a IRF MOSFET is always a case of possible pig in a poke. Some of
them will not work no matter what one does to them.

Re: On the subject of fake IRF510

Andrew Krause
 

Is there an alternative in a TO-220 package? 

On Sat, Jul 15, 2017 at 6:22 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
I find this post from Allison to be informative, she definitely knows what she's doing:  
    https://groups.io/g/BITX20/message/22597 

There are issues with the IRF510 as an RF amp.
Primary issue is poor thermal conductivity from die to TO-220 tab.
Also, the tab is connected to the drain, not the source as it would be in a good RF device,
so be careful not to short the heatsink to ground!  (Or add a $0.05 mica insulator and heatsink paste.)  
The IRF510 does work better at 24v than at 12v, giving better linearity.

But otherwise, Allison reports that the IRF510's  behavior is similar to
the 10x more expensive RF devices such as the RD16HHF1.
She continues to use the IRF510.

Jerry, KE7ER



On Sat, Jul 15, 2017 at 02:45 pm, John Backo wrote:
using a IRF MOSFET is always a case of possible pig in a poke. Some of
them will not work no matter what one does to them.




--

Andrew Krause
General Class Amateur Radio License: KM4ZJO
andrew.krause@...
(404) 732-2369



Re: W8TEE TFT/ VFO DISPLAY BOARD BOARD

K5ESS
 

John,
I've ordered 5v 30MHz replacement oscillators from Mouser for my AD9851 boards but I haven't found any 5v 125MHz oscillators for the AD9850s. If you know of a source I'd appreciate knowing where you can get them.
Mike
K5ESS

-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of John Backo via Groups.Io
Sent: Saturday, July 15, 2017 5:04 PM
To: BITX20@groups.io
Subject: Re: [BITX20] W8TEE TFT/ VFO DISPLAY BOARD BOARD

Good thought, Mike.

I think what happened is that a huge quantity of these devices were made, and a certain quantity of them were shipped with iffy crystal oscillators.
They became part of the mix and were sold sort of as-is.

Then it was discovered that many, if not all, of the output filters were wrongly configured. That caused all of them to be dumped on the open market.
For a time, they were freely available and cheap. Then, when the demand was verified and supply ran out, a new batch was made which are currently for sale (and more expensive). These newer ones should have better quality...but I wonder.

It is easy to operated the 3.3v oscillators at 5v. It changes the frequency a bit, but not much else. However, it does put a strain on them and they can fail early.
You can also usually operate the 5v units at 3.3v. Mostly, they oscillate at about the right frequency. I would suppose they last somewhat longer, but I have not verified that.
Proper oscillators are easily available (now) and replacement is easy. So there is no real problem, I guess.

john
AD5YE

Re: BITX echolink node

Joe
 

Good idea.

Joe
Ve1bwv


On Sat, Jul 15, 2017, 6:56 PM David Woodward <kf4wbj2@...> wrote:
While this is a great group with many capable people, it is way too slow in response time.
 Wouldn't an echolink node strictly for bitx related things be more convenient? 
 What are your thoughts?

Re: BITX echolink node

ron van doremalen (PA3FAT)
 

No need. If you need fast response times consider Elecraft. This is a 50$ kit.

Get real

Sent from my iPhone

On 15 Jul 2017, at 23:56, David Woodward <kf4wbj2@...> wrote:

While this is a great group with many capable people, it is way too slow in response time.
 Wouldn't an echolink node strictly for bitx related things be more convenient? 
 What are your thoughts?

Re: I don't believe it!

Dexter N Muir
 

Thanks, John P, your Molex tip is known - that's what I meant by "Molex surgery".
A gentle twist of the wrist with small 'sidecutters' can undo the first crimp (as you approach along the wire) to extract the remnant wire-jacket. The remaining scrap of bare wire is inconsequential.
BTW 'sidecutters' are NOT 'Diagonal cutters'. The former profile at the cutting point can cut level to a PCB surface: " _\ /_". The latter are more "><". 'Cheapos' tend to be the former, so us frugal Hams are well-catered-to. My 'Trade' quality cutters are Japanese copies of Xcelite (or perhaps Snap) - designed *for* the Electronics trade. Steer clear of Hardware/DIY store gear - they're more likely to be the latter.

Re: BITX echolink node

 

wow Ron just wow ............Don't see what the price has to do with people wanting to chat or help with the bitx live.......in fact when I had a elecraft (k1) they were pretty rude and not helpful at all unless I was willing to "upgrade" to the 1000$ model.

 

 An Echo link node would be cool for chat on the bitx. I would pop in for sure.

Re: I don't believe it!

Andrew Krause
 

Is this related to the solar flare earlier this week, maybe?

Re: BITX echolink node

Andrew Krause
 

My sentiments exactly. The tradeoff with free tech support from a third party group of volunteers might include long wait times. (And snark.) :)

On Sat, Jul 15, 2017 at 7:12 PM, ron van doremalen (PA3FAT) <ronvandoremalen@...> wrote:
No need. If you need fast response times consider Elecraft. This is a 50$ kit.

Get real

Sent from my iPhone

On 15 Jul 2017, at 23:56, David Woodward <kf4wbj2@...> wrote:

While this is a great group with many capable people, it is way too slow in response time.
 Wouldn't an echolink node strictly for bitx related things be more convenient? 
 What are your thoughts?




--

Andrew Krause
General Class Amateur Radio License: KM4ZJO
andrew.krause@...
(404) 732-2369



Re: BITX echolink node

Doug W
 

I like the idea of something real time especially for last minute OSO attempts.   this site has a chat function that the group owner needs to activate.  sounds easier than needing another program.

Re: BITX echolink node

Michael Hagen
 

Amen Dude!

What the heck is echolink node?

This is a Hobby and Fun.

We don't need the "Red Phone"!

We don't need the "Emergency Ward".

It should not be about Instant Gratification.

Buy several BitX Kits, they are FUN.

Learn Lots!


Mike, WA6ISP


On 7/15/2017 4:12 PM, ron van doremalen (PA3FAT) wrote:
No need. If you need fast response times consider Elecraft. This is a 50$ kit.

Get real

Sent from my iPhone

On 15 Jul 2017, at 23:56, David Woodward <kf4wbj2@...> wrote:

While this is a great group with many capable people, it is way too slow in response time.
 Wouldn't an echolink node strictly for bitx related things be more convenient? 
 What are your thoughts?

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

Re: BITX echolink node

Ken Hansen
 

I can't find a 'chat' function in group.io...

Ken, N2VIP

On Jul 15, 2017, at 6:34 PM, Doug W <KD9CYF@...> wrote:

I like the idea of something real time especially for last minute OSO attempts.   this site has a chat function that the group owner needs to activate.  sounds easier than needing another program.

Re: BITX echolink node

David Woodward
 

yes for troubleshooting and qso coordination...the Bitx40 and ubitx has the capability to revolutionize our ham radio hobby in a positive way....

On Jul 15, 2017 7:52 PM, "Ken Hansen" <ken@...> wrote:
I can't find a 'chat' function in group.io...

Ken, N2VIP

On Jul 15, 2017, at 6:34 PM, Doug W <KD9CYF@...> wrote:

I like the idea of something real time especially for last minute OSO attempts.   this site has a chat function that the group owner needs to activate.  sounds easier than needing another program.