开云体育

  1. BITX20
  2. Messages
Expanded Topics Messages Polls
Date
Re: missing c103

Billy Shepherd
 

Thanks so much!


From: BITX20@... [mailto:BITX20@...]
Sent: Wednesday, January 04, 2017 7:23 PM
To: BITX20@...
Subject: [BITX20] Re: missing c103



Billy - Ashar's receiver troubleshooting video gives an overview of the board and talks about where and why some of the parts might be missing. My recent pre-Raduino didn't need C103 either.

Cheers,
Andy


Troubleshooting the BITX40 board's receiver<>


[Image removed by sender. image]<>

Troubleshooting the BITX40 board's receiver <>
A short video showing how to troubleshoot the receiver of the BITX40 with a piece of wire

View on www.youtube.com <>

Preview by Yahoo
Re: missing c103

 

Billy - Ashar's receiver troubleshooting video gives an overview of the board and talks about where and why some of the parts might be missing. ?My recent pre-Raduino didn't need C103 either.

Cheers,
Andy


?
missing c103

Billy Shepherd
 

开云体育

Missing C103 (the potentiometer? for the balanced modulator) from my recently received Bitx40. Is this normal? Mine is the unit without the Raduino. If it’s an error would adding it myself be considered a novice task? Thanks.

?

Billy

?
Re: Si5351 VFO - Low Pass?

 

Very informative.

On Wed, Jan 4, 2017 at 4:55 PM, steve@... [BITX20] <BITX20@...> wrote:
?

The diode-ring mixer operates by switching the RF signal straight through to the IF port on one half-cycle of the local oscillator, then switching an inverted version of the RF signal through to the IF port on the next half-cycle. It doesn't depend on the non-linearity of the diodes for its operation - it treats them as switches. Best inter-modulation performance comes from keeping the diodes hard on or hard off, minimizing the time for which they are in an intermediate state.

Steve G3TXQ




--
Mark Baldridge
608.561.3853
Re: the arrival

Billy Shepherd
 

December 16th. Waiting to here back…the potentiometer for the balanced modulator is missing…not sure if this is just a redesign. Mine came without the Raduino.

Billy Shepherd
Bartholomew Co 911 Center
131 S Cherry St.
Columbus, IN 47201

From: BITX20@... [mailto:BITX20@...]
Sent: Wednesday, January 04, 2017 5:52 PM
To: BITX20@...
Subject: Re: [BITX20] the arrival


Great! What date did you order it?

Rich
KC8MWG

On Wednesday, January 4, 2017 2:13 PM, "Billy Shepherd billy.shepherd@... [BITX20]" <BITX20@...> wro te:


2 weeks to ship for free from India to Indiana, awesome!
[cid:image001.jpg@...][cid:image002.jpg@...]
[cid:image003.jpg@...]
Re: Si5351 VFO - Low Pass?

 

The diode-ring mixer operates by switching the RF signal straight through to the IF port on one half-cycle of the local oscillator, then switching an inverted version of the RF signal through to the IF port on the next half-cycle. It doesn't depend on the non-linearity of the diodes for its operation - it treats them as switches. Best inter-modulation performance comes from keeping the diodes hard on or hard off, minimizing the time for which they are in an intermediate state.

Steve G3TXQ
Re: the arrival

 

Great! What date did you order it?

Rich
KC8MWG


On Wednesday, January 4, 2017 2:13 PM, "Billy Shepherd billy.shepherd@... [BITX20]" wrote:



?
2 weeks to ship for free from India to Indiana, awesome!
[cid:image001.jpg@...][cid:image002.jpg@...]
[cid:image003.jpg@...]

[Non-text portions of this message have been removed]
Re: Band Pass Filter High Attenuation

 

Okay. That is helpful information.

A couple questions:?

1: Can I assume that I will for the most part tune the inductors together? To make the correct bandpass, they must all be the same value, right?

2: Can I attach a 50 ohm spectrum analyzer as I showed in the link? Or will the impedance mismatch cause the filter to not function properly?


On Tue, Jan 3, 2017 at 12:41 AM, iam74@... [BITX20] <BITX20@...> wrote:
?

As I recall, this BPF is about 200 ohms in and out. If you used the IF transformers supplied with the kit, suspect first the coils of these transformers.? They are quite fragile and it is easy to get a poor or nonexixtent connection through them.

First, were they oriented right?

Second, it is easy to pull one of the pins out of alignment and even break the connection internally. Check them very carefully.

Third, there is a specific and quite narrow window which creates the bandpass. Triple check your alignment. The proper final inductance should be about 4 uH (for 20m).

Hope this helps.

john
AD5YE


---In BITX20@..., wrote :

Greetings all.

I seem to have an issue with my Band Pass Filter.

This was built using the components from Sunil Lakhani on eBay.

----

The entire schematic is here:?




--
Mark Baldridge
608.561.3853
Re: Si5351 VFO - Low Pass?

 

THIS WAS MY QUESTION ALSO. Very curious what people have to say. :)

On Wed, Jan 4, 2017 at 2:49 PM, steve@... [BITX20] <BITX20@...> wrote:
?

Isn't it better to drive a diode-ring mixer with a square-wave local oscillator? You're wanting to switch the diode pairs hard on, then hard off.

Steve G3TXQ




--
Mark Baldridge
608.561.3853
Re: BITX40: Delay of PTT, RX amp keeps active too long

 


I doubt my previous suggestion of "Swap ?pins 3 and 5 of relay K2, add a 100k resistor from K2-1 to ground" would do anything but make the transition noisier.?
Re: Si5351 VFO - Low Pass?

 

Isn't it better to drive a diode-ring mixer with a square-wave local oscillator? You're wanting to switch the diode pairs hard on, then hard off.

Steve G3TXQ
Si5351 VFO - Low Pass?

 

Any thoughts on the 'proper' selection of a low-pass filter for the output of an Si5351? ?Is it sane to think about a 60 meter low pass for the 4.7-5 MHz, or would most anything work to clean the signal as long as it passes 4.7-5?


Thanks!

Andy
Re: LED for XMIT indication

 

Would You please upload a photo which shows the points you use ?

Thanks in advance

Walter

Dortmund, Germany
Re: LED for XMIT indication

 

Here's what I did - I tapped the TX / RX +12 points from the relay closest to the Power Connector.

This will give you +12 on RX, then on PTT, RX goes to zero (or nearly) and TX goes +12.

This way, you can use a Red / Green Bi-Color LED.
Green for 'ON / RX'
Red for 'PTT / TX'

In fact, there's a convenient spot near that relay, toward the corner, where you can glue or
hot-glue a 3-pin connector (just like the ones on-board), but flush with the bottom of the
PCB. Now you have a convenient plug-in point for your Red/Green LED.

Since both LEDs won't be on at the same time, they can share a single current limiting
resistor in the 'common' or 'ground' leg of the connector headed out to the Bi-Color LED.

I think current draw for Red and Green are slightly different, but I just picked a resistor which
would give me the most even light from each. Current draw is probably under 10 ma. for these
LEDs, but it is a nice feature. You can tell if PTT is working.

Mike Yancey, KM5Z
Dallas, Texas
the arrival

Billy Shepherd
 

2 weeks to ship for free from India to Indiana, awesome!
[cid:image001.jpg@...][cid:image002.jpg@...]
[cid:image003.jpg@...]
Re: BITX40: Delay of PTT, RX amp keeps active too long

 

Good question regarding why D18 is in there.

The diodes are needed on the bidi RF amps, as Ashhar notes in his circuit description:

? "The diodes in the collectors prevent the switched-off transistor's collector resistor (220 ohms) from loading the input of the other transistor."

If D18 were not there, then C110 will supply power to the rx side of those bidi amps for a second or so after you hit the PTT switch. ?With that rx side diode conducting we are back to the problem of the rx side 220 ohms loading the input of the tx amp.

You could use a relay instead of my fet or npn to discharge C110 ?to ground through a 100 ohm resistor.
And you could use that relay (or my fet or npn) to discharge the entire rx 12v rail as you suggest, though you would either have to remove D18 or put a resistor across it. ?Think about what happens if some sort of fault causes whatever npn/fet/relay to turn on while the rx rail is powered up (hence the 100 ohm resistor).

I only suggested the IRF510 because it is so monstrous and easy to hack with. ?Could just as well be a surface mount 2n3904, since the current involved is only 12v/100 = 120ma, and only happens for roughly 470uF*100ohms ?= 0.047 seconds. ?If using an npn there, you would want a resistor from base to the tx rail of around one to 10 kohms to limit the base current.

Jerry, KE7ER


---In BITX20@..., <ronvandoremalen@...> wrote :

Assume RX is pulled to ground by K1 relay. Would it be a solution to discharge via diode/resistance combination just in front of D18. What’s the actual use of D18 btw?

?

Ron – PA3FAT

___
Re: Highlighted signal path drawings

 

randy,?

post it to me directly at farhanbox@... and i will put it up on the bitxhacks blog, thanks for the effort!

- f

On Wed, Jan 4, 2017 at 11:00 PM, listk7age@... [BITX20] <BITX20@...> wrote:
?

Hi


I was looking over the BITX 40 schematic last night before watching Farhan on Tom's W5KUB show. At first, I was a bit confused with the signals flowing back and forth around the two-way amps. I thought I would grab my highlighter pen and mark up the schematic.


But, then I thought maybe others are also confused when first looking at the schematic. So, I made two drawings?in the computer this morning that shows the receive and transmit path. You will find these drawings in my K7AGE directory,


I also included the LibreOffice Draw files. If I have made any mistakes, please let me know. You can also modify the original files if you would like. All open source!


Hope this helps,


Randy, K7AGE
Highlighted signal path drawings

 

Hi


I was looking over the BITX 40 schematic last night before watching Farhan on Tom's W5KUB show. At first, I was a bit confused with the signals flowing back and forth around the two-way amps. I thought I would grab my highlighter pen and mark up the schematic.


But, then I thought maybe others are also confused when first looking at the schematic. So, I made two drawings?in the computer this morning that shows the receive and transmit path. You will find these drawings in my K7AGE directory,


I also included the LibreOffice Draw files. If I have made any mistakes, please let me know. You can also modify the original files if you would like. All open source!


Hope this helps,


Randy, K7AGE
Re: BITX40: Delay of PTT, RX amp keeps active too long

 

开云体育

Hi Jerry,

?

Assume RX is pulled to ground by K1 relay. Would it be a solution to discharge via diode/resistance combination just in front of D18. What’s the actual use of D18 btw?

?

Ron – PA3FAT

___
New file uploaded to BITX20

BITX20@yahoogroups.com
 

Hello,


This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.


File : /K7AGE/BITX 40 transmit signal path.pdf
Uploaded by : wa2age2001 <listk7age@...>
Description : BITX 40 Highlighted transmit path


You can access this file at the URL:



To learn more about file sharing for your group, please visit:



Regards,


wa2age2001 <listk7age@...>
96421 - 96440 of 116178