Date   
Re: Frequency Counter

Michael Hagen
 

You might put a 1K in series with the input.  Thus it would take a larger signal but load the test circuit less.

Try on the gate of the IRF510?  That's a pretty good stiff signal at your transmit frequency.

Try it on the SL5351 output.

It is good to experiment, this radio has a lots to learn about!

It is a wonderful base to experiment with.  I will use mine mostly for playing with the receiver and Arduino code.

I don't have an antenna.  So it will be a long wire out the door and /or the Signal Generator!

I have already made PCBs (stamp sized) for the Silicons Labs oscillator and have a Nano driving it with I2C.

The examples in the Arduino Code work!  Sweeping, Fixed Freq. ect.  The library makes it magic.

Mike, WA6ISP


On 4/2/2017 11:27 AM, richard kappler wrote:
Nothing in particular, trying to learn.

On Apr 2, 2017 2:25 PM, "Michael Hagen" <motdog@...> wrote:

What do you want to measure?


It has 100 Ohm input resistance on input transistor base ( Cap Coupled).  So you need to find a signal somewhere that this low impedance won't load down?


Mike, WA6ISP


Re: Raduino BFO hook up?

Dr Fred Hambrecht
 

The sketch by Gene Marcus W3PM can be found in the group and does what you want.

 

v/r

Fred W4JLE

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Mike via Groups.Io
Sent: Sunday, April 2, 2017 7:53 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Raduino BFO hook up?

 

Does anyone know of Arduino code that works on a Arduino with an encoder that handles 10 MHZ and below (LSB) and above USB with the correct frequency readout? The Pa3fat code I am using works well below 10 MHZ but 20 meters I am at 9MHZ and tuning is backwards (when display shows going up in frequency.. Output is actually going down) which makes converting tuff!

Re: Frequency Counter

richard kappler
 

Nothing in particular, trying to learn.

On Apr 2, 2017 2:25 PM, "Michael Hagen" <motdog@...> wrote:

What do you want to measure?


It has 100 Ohm input resistance on input transistor base ( Cap Coupled).  So you need to find a signal somewhere that this low impedance won't load down?


Mike, WA6ISP

Re: Frequency Counter

Michael Hagen
 

What do you want to measure?


It has 100 Ohm input resistance on input transistor base ( Cap Coupled).  So you need to find a signal somewhere that this low impedance won't load down?


Mike, WA6ISP

Re: Frequency Counter

Arv Evans
 

Richard W2KAP

It is normal to connect your frequency counter to the VFO output, and to program
in an IF offset.  This lets the counter tell you the operating frequency when receiving
and transmitting.  Connecting the counter to the antenna port could be bad for several
reasons.  (1) it would only show frequency when transmitting. and (2) the RF power
available at the antenna port when transmitting could do bad things to your frequency
counter.

Arv  K7HKL
_._


On Sun, Apr 2, 2017 at 12:11 PM, richard kappler <richkappler@...> wrote:
I am working on strengthening my kit building skills before I tackle my next Bitx40, so I have built the qrpguys frequency counter and should have the parts for a coupla antenna analyzers tomorrow.

Regarding the freq counter, it has 4 "inputs", a pair of grounds, 8-15 VDC and sig in. I have two questions:
1. Any reason I shouldn't hook the VDC in to the incoming power for the BitX? 

2. Regarding Sig In, I should connect this to the brown (center) of the antenna output?

regards, Richard

--
W2KAP

In any given circuit, the most expensive part will always sacrifice itself to protect the fuse.



Frequency Counter

richard kappler
 

I am working on strengthening my kit building skills before I tackle my next Bitx40, so I have built the qrpguys frequency counter and should have the parts for a coupla antenna analyzers tomorrow.

Regarding the freq counter, it has 4 "inputs", a pair of grounds, 8-15 VDC and sig in. I have two questions:
1. Any reason I shouldn't hook the VDC in to the incoming power for the BitX? 

2. Regarding Sig In, I should connect this to the brown (center) of the antenna output?

regards, Richard

--
W2KAP

In any given circuit, the most expensive part will always sacrifice itself to protect the fuse.


Re: 25 volts and output wattage

Jerry Gaffke
 

If interested in pushing the IRF510, read what kb1gmx has to say in this old thread:  https://groups.io/g/BITX20/topic/4104262#14524

Better yet, all kb1gmx posts to this forum.  Plus EMRFD.

Alternately, I suggest you buy IRF510's in hundred lot quantities.  And some safety goggles.


On Sat, Apr 1, 2017 at 12:38 pm, Jerry Gaffke wrote:

Could in theory we go higher than 25 watts or would that blow a circuit? Say 36 watts with enough cooling to get maybe 40w or more out?

 

Re: No audio driver, now RF Probes

Michael Hagen
 

Those eBay ones are nifty, I want one.  But, they are 50 Ohms, so not so good at poking around circuits that may be several K Ohms?

Mike, WA6ISP

Re: No audio driver

Jack Purdum <econjack@...>
 

Dennis and I are finishing up work on an AGC board, from which we grab the S meter data. By having the takeoff for the AGC in the RF chain, Dennis has a pretty good S meter (i.e., not a VU meter). I've also added a little more detail to the S meter graphic to make it look more like an S meter. I'll let the group know where we're done hacking away!

Jack, W8TEE


From: Jerry Gaffke via Groups.Io <jgaffke@...>
To: BITX20@groups.io
Sent: Sunday, April 2, 2017 11:52 AM
Subject: Re: [BITX20] No audio driver

If you must have a log amp, I'd make pads for an optional AD8310 (the improved and cheaper AD8307)  on the main board and have it drive a Nano analog input.  Make a dandy S meter when not being used to troubleshoot the Bitx or perhaps other gear.  Those that want it could go out and buy one, or you could make the extra part a buying option at hfsigs.
Of course, we'll quickly run out of Nano pins.  I still like the idea of the Si5351 on the main board, a connector off to the microcrontroller/display of our choice.  I'd go Teensy 3.2, likely never run out of pins or anything else (mips, flash, ram, ADC bits, serial ports, ...).
On Sun, Apr 2, 2017 at 01:12 am, Raj vu2zap wrote:
How about this Farhan?  http://www.ebay.com/itm/182209512477 It should do, very economical RF probe! 

 


Re: No audio driver

Jerry Gaffke
 

If you must have a log amp, I'd make pads for an optional AD8310 (the improved and cheaper AD8307)  on the main board and have it drive a Nano analog input.  Make a dandy S meter when not being used to troubleshoot the Bitx or perhaps other gear.  Those that want it could go out and buy one, or you could make the extra part a buying option at hfsigs.

Of course, we'll quickly run out of Nano pins.  I still like the idea of the Si5351 on the main board, a connector off to the microcrontroller/display of our choice.  I'd go Teensy 3.2, likely never run out of pins or anything else (mips, flash, ram, ADC bits, serial ports, ...).

On Sun, Apr 2, 2017 at 01:12 am, Raj vu2zap wrote:

How about this Farhan?  http://www.ebay.com/itm/182209512477 It should do, very economical RF probe! 


 

Re: New to group -- exploring multiband capabilities

Jerry Gaffke
 

Etherkit has:  https://www.etherkit.com/rf-modules/si5351a-breakout-board.html


On Sun, Apr 2, 2017 at 08:17 am, cove37 wrote:

 BTW, has anyone successfully dropped a TCXO in place of the oscillator crystal?

 

Re: No audio driver

ohwenzelph
 

anyone have a better idea of a simple 2-3 component rf detector?

- f


Well, not as cheap as the eBay one but could this be useful?


Jer AA1OF

Sent from my iPad

Re: New to group -- exploring multiband capabilities

cove37
 

Ok, that covers my concerns about using all the clock outputs.  As for the GPS disciplining, I was going to lift the code from QRP Lab's Progrock and use a GPS receiver's 1PPS signal.  Not cheaper or easier, just a fun way of assuaging the clock freak in me.  BTW, has anyone successfully dropped a TCXO in place of the oscillator crystal?

Re: No audio driver

Jerry Gaffke
 

I haven't had reason to play with diode RF probes.  But here's a quote from  http://www.tuberadioforum.com/t4138-simple-rf-probe-for-my-dmm  suggesting they work well enough at far far lower RF voltages than you might think:

  This one is a bit more sophisticated. It is still a passive probe, but can be calibrated in both output and linearity. Its minimum sensitivity is about 2.3 mVrms input, and in testing so far, has an essentially a flat response from high audio frequencies to about 30 MHz I have not gone beyond that, but it should be good to 100 MHz or so.  The main difference with this RF probe is the fact that it is just about dead on 1:1 RMS input to DC output from 150 mV to past 15V. Again, it should continue to be linear, but I have not tested its voltage response beyond about 26 dB.

Most of the RF probe designs out there use the meter's internal resistance in series with a resistor in the RF probe to convert pk-to-pk into rms voltage.  Careful with that if using an external meter, as they can have an order of magnitude difference in internal resistance.  

Another point often not mentioned is that the probes use that series resistor in the probe plus any stray capacitance inside the meter to form a low pass filter, creating the DC voltage that gets measured.


On Sun, Apr 2, 2017 at 07:53 am, Jerry Gaffke wrote:

Actually, a germanium (and likely even schottky) diode probe can work down below 100mv if the current is kept low enough

 

Re: No audio driver

Soundararajan Ra.
 

I hope we can use RF probe with germanium diode when set righting a nonworking BITX by comparing working BITX rig..

On Sun, Apr 2, 2017 at 8:23 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Actually, a germanium (and likely even schottky) diode probe can work down below 100mv if the current is kept low enough (if the voltmeter is at least a megaohm or so).  That curve is exponential, not two straight lines meeting at a "knee" as we (and LTSPICE) usually think of it.  Below 100mv the results can be repeatable though certainly not linear.  If we use an analog input to the Nano as the voltmeter, then everybody will have about the same voltmeter input impedance to better compare results.

> The diode probes work only above 1v levels.


Re: No audio driver

Jerry Gaffke
 

Actually, a germanium (and likely even schottky) diode probe can work down below 100mv if the current is kept low enough (if the voltmeter is at least a megaohm or so).  That curve is exponential, not two straight lines meeting at a "knee" as we (and LTSPICE) usually think of it.  Below 100mv the results can be repeatable though certainly not linear.  If we use an analog input to the Nano as the voltmeter, then everybody will have about the same voltmeter input impedance to better compare results.

> The diode probes work only above 1v levels.

Re: No audio driver

Jerry Gaffke
 

Could use the diode probe if a signal is injected into the amp with some kind of probe, giving a response 2 or 3  times bigger than it normally is.


On Sun, Apr 2, 2017 at 06:01 am, Ashhar Farhan wrote:

The difficulty with a good procedure to align the the tx is that, it needs to 'see' the RF at fairly low levels of 100 mv or so.

 

Re: New to group -- exploring multiband capabilities

Jerry Gaffke
 

I've heard that using CLK0 and CLK2 with CLK1 forced low does alright.  Turning on CLK1 to use all 3 does create some crosstalk as they are all operating from the same VCCIO supply.  Ashhar apparently found that not to be a significant issue on the uBitx, though if not to your taste you could spend another $1USD on a second Si5351 (and figure out some way to talk to the second I2C port).  A VXO on the BFO works, but having an Si5351 channel for the BFO makes it easily adjusted for alignment and USB/LSB/CW selection.  The Si5351 only has two PLL's internally, but the fractional dividers on the outputs allow more than enough resolution for our purposes.

Exactly how would you use CLK2 for GPS calibration?  I'm thinking the ideal (and cheapest) way to calibrate is to set it up as a 10mhz WWV receiver (or your favorite HF time standard signal at most any frequency), look for zero beat.  That zero beat will depend on all three uBitx local oscillators, but since they are all operating from the same reference oscillator the calculations for the correction factor are trivial.

Jerry, KE7ER


On Sun, Apr 2, 2017 at 06:23 am, cove37 wrote:

I'm also guessing someone's solved the interrelational problems with clk1 and 2 to get the desired frequencies from all 3 outputs.  I still would be ok with using a VXO for the BFO so I could use the clk2 for GPS calibration.

 

Re: No audio driver

Al Duncan VE3RRD
 

If you now have no output when you speak into the mic, but the receive is OK (but everything worked OK previously); then another component to check is Q13. Although Q13 is in the TX path, it is left in the circuit during RX. If you have transmitted on another 100W or higher power rig while the Bitx40 was in RX mode on a nearby antenna,then there is a good chance you have blown Q13 - if you didn't install the two 1N4148 protection diodes between K1 pin 12 and ground. The picture in the following message shows the location on the board:

https://groups.io/g/BITX20/message/22844?p=Created,,,20,1,0,0::Created,,minimum+mods,20,2,40,4415405

Placing them between pin 12 and ground means they are only in the circuit during RX; you might not want an extra couple of non-forward biased diode junctions in the TX path during transmit that could generate noise, harmonics etc. Q13 can be replaced by a 2N3904.

Re: New to group -- exploring multiband capabilities

cove37
 

Thanks for the info.  The uBitx system looks promising also.  If no one is having problems with the 12mhz IF, then I'll stick with it.  10.7 is convenient because you can buy matched crystals for that freq off the shelf.  I'm also guessing someone's solved the interrelational problems with clk1 and 2 to get the desired frequencies from all 3 outputs.  I still would be ok with using a VXO for the BFO so I could use the clk2 for GPS calibration.

Thanks

Burton Ison
W5IAC


On Saturday, April 1, 2017 4:06 PM, cove37 via Groups.Io <cove37@...> wrote:


Hello all,

A couple of questions to bounce off all -- since the IF is 12Mhz (maybe change to 10.7 to get it further from 20m), couldn't 20-10 meters use the mixer sum, instead of difference, and this would automatically switch the sideband to upper?  Also, would it simplify the filtering to use a robust bandpass filter for each band for both T and R, eliminating the need for a separate LPF?


Thanks

Burton Ison
W5IAC