Date   
Re: elves are at it

Michael Hagen
 

Oh WOW!  What a wonderful sight.  They are going to be working from now util Next Christmas!

They really look nice!

Congratulations Ash




On 12/3/2017 8:06 AM, Ashhar Farhan wrote:

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

Re: Choosing a toroid for impedance matching from antenna to NE602

Jerry Gaffke
 

Here's an interesting document regarding impedance matching networks to feed the 602/612 mixers: 
https://www.nxp.com/docs/en/application-note/AN1994.pdf
 
Page 3 tells us that the SA602A has the same mixer as the SA605, as described in this app note.
Page 3 includes some other history, but never quite says what an SA612A is (only what the SA612 was).
Page 6 shows that when driven single ended at 10mhz, the input impedance is around 5k
Page 9 reminds us that when driving the mixer differentially, that input impedance is doubled to 10k.

Page 4 of the datasheet:   https://www.nxp.com/docs/en/data-sheet/SA612A.pdf
says   "AC input impedance is approximately 1.5k || 3 pF through 50 MHz."
I'm pretty sure that would be doubled to 3k when driven differentially.
Since this is a later document than AN1994 and is specific to the currently available SA612A,
seems more likely to be correct with regard to the input impedance.  But that's by no means certain.


This blog posts suggests that for all parts currently available, the 602's are the same as the 612's.
The story conflicts a bit with AN1994 page 3 in that it claims the upgraded part was called the 612, not the 602A.
Never says anything about the A variants, though that transition happened around 1990, long before this was written.
Also explains that the NE612 was good only from 0-70C, whereas the SE612 is good from -40 to 85C.
The only 602/612 part I see being sold these days is the SA612AD.

http://soldersmoke.blogspot.com/2009/06/na5n-on-ne602.html

If you don't need to wring every ounce of gain from these mixers
should be ok to drive them from a lower impedance source.
Some successful QRP rigs just drive them from 50 ohms single ended,
as atmospheric noise tends to predominate at HF anyway.


Jerry, KE7ER



On Sun, Dec 3, 2017 at 03:47 am, Kerr Smith wrote:
... I have chosen to use 1500 ohms but Jean-Matthieu calculations suggest 3472 ohms?

Re: elves are at it

Jerry Gaffke
 

I know what I'm getting for Christmas.
And maybe a friend or two as well.


On Sun, Dec 3, 2017 at 08:38 am, Ashhar Farhan wrote:
soon...

Re: BITX QSO Night, Sunday, December 3, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

John P
 

I still plan on being on at 3PM EST (2000 UTC) and again this evening.
--
John - WA2FZW

Re: elves are at it

Jorge Luiz Fenerich
 

   Great Ashhar, do not make us suffer !!! I'm in line for one of these okay?
  Jorge PY2PVT _._

2017-12-03 14:06 GMT-02:00 Ashhar Farhan <farhanbox@...>:




--
  73 de Jorge PY2PVT
  Campinas SP
  GG67MD

Re: elves are at it

philip yates
 

And me.... Santa asked me what I wanted.

Phil - G7BZD

On Sun, Dec 3, 2017 at 7:30 PM, Jorge Luiz Fenerich <py2pvt@...> wrote:
   Great Ashhar, do not make us suffer !!! I'm in line for one of these okay?
  Jorge PY2PVT _._

2017-12-03 14:06 GMT-02:00 Ashhar Farhan <farhanbox@...>:




--
  73 de Jorge PY2PVT
  Campinas SP
  GG67MD


Re: elves are at it

Craig Wadsworth <cwadsworth@...>
 

“It’s beginning to look a lot like Christmas . . . “
They look fine! Nice work, Ash.

Re: elves are at it

Karl Heinz Kremer, K5KHK
 

How about a secret pre-order process just for us? :)


Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...


On Sun, Dec 3, 2017 at 2:59 PM, Craig Wadsworth <cwadsworth@...> wrote:
“It’s beginning to look a lot like Christmas . . . “
They look fine!  Nice work, Ash.




Re: BITX QSO Night, Sunday, December 3, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

Tom VE3THR
 

I got an amateur on AM on 7.275, the AM broadcast station also on 7.275 and another AM broadcast station on 7.285. There is all kinds of AM broadcasts right now between 7.120 and 7.300. Another qso on 7.177. Going to try 7.262 for a while on the Kenwood @ 2005 HRS zulu.
Good luck guys...lets try anyway.

Re: elves are at it

Roy Appleton
 

So what is the story of these? I assume that they are a multi band ubitx? 

Roy
WA0YMH

On Dec 3, 2017 10:06 AM, "Ashhar Farhan" <farhanbox@...> wrote:

Re: BITX QSO Night, Sunday, December 3, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

Vince Vielhaber
 

I'm on the Kenwood on the Buzzards net/pre-net on 3929. I'll check the 40M freqs off an on thru the evening.

Vince.

On 12/03/2017 03:08 PM, Tom VE3THR wrote:
I got an amateur on AM on 7.275, the AM broadcast station also on 7.275
and another AM broadcast station on 7.285. There is all kinds of AM
broadcasts right now between 7.120 and 7.300. Another qso on 7.177.
Going to try 7.262 for a while on the Kenwood @ 2005 HRS zulu.
Good luck guys...lets try anyway.

Re: elves are at it

Jerry Gaffke
 

Yup, the multiband ubitx.
Probably pretty close to the schematic shown here:  https://groups.io/g/BITX20/message/33255

Jerry, KE7ER


On Sun, Dec 3, 2017 at 12:11 pm, Roy Appleton wrote:
So what is the story of these? I assume that they are a multi band ubitx? 
 

Re: BITX QSO Night, Sunday, December 3, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

John P
 

Sorry, but I didn't quite make 3PM!! I'm on 7277 now. Frequency seems quiet.
--
John - WA2FZW

Re: BITX QSO Night, Sunday, December 3, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

John P
 

On 7277 with VE3THR now! Signals aren't great, but workable!
--
John - WA2FZW

Re: Choosing a toroid for impedance matching from antenna to NE602

Norberto Modanesi
 

Have a look at this link

http://w7zoi.net/transformer_coupled_lc_bpf.pdf

 

73 – LU5DNM

 

De: BITX20@groups.io [mailto:BITX20@groups.io] En nombre de Jerry Gaffke via Groups.Io
Enviado el: domingo, 03 de diciembre de 2017 01:55 p.m.
Para: BITX20@groups.io
Asunto: Re: [BITX20] Choosing a toroid for impedance matching from antenna to NE602

 

Here's an interesting document regarding impedance matching networks to feed the 602/612 mixers: 
https://www.nxp.com/docs/en/application-note/AN1994.pdf
 
Page 3 tells us that the SA602A has the same mixer as the SA605, as described in this app note.
Page 3 includes some other history, but never quite says what an SA612A is (only what the SA612 was).
Page 6 shows that when driven single ended at 10mhz, the input impedance is around 5k
Page 9 reminds us that when driving the mixer differentially, that input impedance is doubled to 10k.

Page 4 of the datasheet:   https://www.nxp.com/docs/en/data-sheet/SA612A.pdf
says   "AC input impedance is approximately 1.5k || 3 pF through 50 MHz."
I'm pretty sure that would be doubled to 3k when driven differentially.
Since this is a later document than AN1994 and is specific to the currently available SA612A,
seems more likely to be correct with regard to the input impedance.  But that's by no means certain.

This blog posts suggests that for all parts currently available, the 602's are the same as the 612's.
The story conflicts a bit with AN1994 page 3 in that it claims the upgraded part was called the 612, not the 602A.
Never says anything about the A variants, though that transition happened around 1990, long before this was written.
Also explains that the NE612 was good only from 0-70C, whereas the SE612 is good from -40 to 85C.
The only 602/612 part I see being sold these days is the SA612AD.

http://soldersmoke.blogspot.com/2009/06/na5n-on-ne602.html

If you don't need to wring every ounce of gain from these mixers
should be ok to drive them from a lower impedance source.
Some successful QRP rigs just drive them from 50 ohms single ended,
as atmospheric noise tends to predominate at HF anyway.


Jerry, KE7ER



On Sun, Dec 3, 2017 at 03:47 am, Kerr Smith wrote:

... I have chosen to use 1500 ohms but Jean-Matthieu calculations suggest 3472 ohms?

Re: elves are at it

Doug W
 

Now we need a special edition board with an autographed schematic (suitable for framing of course).

Re: BITX QSO Night, Sunday, December 3, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

John P
 

Had about a 20 minute QSO with Tom (VE3THR; not on his BitX) and worked Mike (WA3O - BitX to BitX) this afternoon. Conditions weren't great; lots of QSB and some broadcast QRM, but seemed a little better than they've been in the evening lately. We'll see what happens at 7PM!
--
John - WA2FZW

Re: elves are at it

MAc B
 

Waiting....

Re: elves are at it

David Woodward
 

haven't had this much anticipation since I was a kid...

On Dec 3, 2017 5:26 PM, "MAc B" <sp9mrn@...> wrote:
Waiting....


Re: elves are at it

Simon Thompson <simonthompson67@...>
 

When can I get one, or two, or three?

On Dec 3, 2017, at 3:30 PM, David Woodward <kf4wbj2@...> wrote:

haven't had this much anticipation since I was a kid...

On Dec 3, 2017 5:26 PM, "MAc B" <sp9mrn@...> wrote:
Waiting....