Date   

Re: Test equipment recommendations

Robert D. Bowers
 

I forgot all about this!

One more (really inexpensive) thing to add to the list - a decent SDR dongle.  I spent less than $30 for mine - and I've used it rather like a spectrum analyzer (1mhz window on frequency - maximum, but any frequency center from below 28 mhz to 1400), it also can be used to check deviation in a FM rig, and when connected to the if of a rig (through a buffer amp) - a VERY sensitive band scope (I've also used it to really clean up signals I couldn't understand).  I use mine with GQRX - quite pleased with it.

A computer (or even tablet/phone) can be used for other tests as well - with decent audio in/out (adequate bandwidth/low distortion).

Bob


Re: Test equipment recommendations

Robert D. Bowers
 

I've thought about a decent SA, but have never had the money (or the luck to find one).  Thanks for the reminder about the RSP1A.

I've been using my SDR dongle for checking spectra - it's limited to 1 mhz of the spectrum at a time, but it CAN be used to check FM deviation and so on - plus purity of signal (and even give indications of how far down spurs and so on are).  That's pretty good for something less than $20 - and I forgot to add that to the list I put up!

Bob


On 5/17/20 11:52 AM, Evan Hand wrote:
For me, the basic is:
1 - DMM
2 - An SWR/Power meter
3 - A 100Mhz or better oscilloscope
4 - A PC

Nice to have if you are going to do surgery, PA mods, or antenna experiments:
1 - An SDR Play RSP1A with a -50 DB tap and step attenuator to use as a Spectrum Analyzer (SA) 
2 - NanoVNA or Antuino (from HF Signals)
3 - 50MHz signal generator

Really nice to have:
1 - 2 GHz spectrum analyzer (Sigelent or Rigol)

All of the DSO Oscilloscopes that I have seen are only good to 1 MHz or so.  You really need the 100 MHz to do testing on a superheterodyne transceiver like the uBITX.

I have been pleasantly surprised by the flexibility and usefulness of the SDR Play RSP1A as a SA.  Of course, I would really like a Sigelent or Rigol SA, just not ready to spend $1,000+.

Above are my thoughts, others may be different, and YMMV.
Good Luck
73
Evan
AC9TU


Re: Test equipment recommendations

Randy.AB9GO
 

Go to a hamfest in your local area when they return ☣️.  It may be hit-or-miss if you find an oscilloscope but if you ask around I'm sure someone will have one that they will sell for a reasonable price or since you're starting out sometimes a freebie comes along that works.  It can be a great source for other test equipment also.  If you buy an oscilloscope locally at least you can try it out and make sure it works. I have found eBay to be really hit or miss and usually much too expensive for test equipment.  To get started a 20 megahertz analog scope is just fine and usually they're quite inexpensive.  Most of us didn't have anything better than that until the rash of cheaper Chinese scopes became available a few years ago.  They just cost too much for the experimenter back in the day.  If you can find a used  Rigol Ds1102E scope they make an excellent entry-level scope. Just don't pay too much for it. $100-$150 would be about the max for it since the newer DS1054Z is out and commonly available for $350. And for that money it must have all the probes included!  

Hopefully you'll be able to find what you need. One thing to remember at hamfests some people price their stuff realistically and it always is a good idea to offer less for the item than the asking price. Most people come down somewhat.  Do a little research and see what things are selling for on websites like eham or qrz.  You always run into the seller though that will not come down in price and their asking price is just ridiculous ie eBay prices and higher.  Just move on to the next table.  Not everyone is trying to find a sucker.  😁

randy.ab9go@....



This message sent to you from my mobile device via speech-to-text technology.


Re: Test equipment recommendations

Robert D. Bowers
 

Digital scopes have some limitations - and to really use them effectively, you do need to know a little about how they work and operate.  That being said, they can be valuable too - even a 5mhz digital scope can work with audio (and to a lesser degree with RF - low frequency stuff).  A 20mhz would work for older radios (with a lower IF), but a 20mhz analog is far easier to use near the top end of its bandwidth than most digital scopes - and have a more accurate representation of the waveform at the upper end.  I'd suggest something at least 30mhz... if digital, go higher than that (better representation of the waveform).  For digital, a good rule of thumb is the bandwidth at least twice the signal you might want to check.

I've got a used analog (bought at a hamfest) which works good - yeah, there's a chance of a lemon but often they're quite rugged (and if they look good inside and out, you've got a pretty fair chance of getting a good one).  Usually a few simple tests can show if there are problems or not.  If it comes on, shows traces, and the seller can show a waveform (square wave is good), usually they're adequate for troubleshooting.  I think that there are lists on the internet that show what tests to do - and what sort of problems you're likely to find based on the make and model of the scope.  IME, the usual failure is dried-out power supply caps. 

Here is a list of suggested test equipment:
  1. A very good DVM - be prepared to spend a fair amount on this.  A cheapo model will work, but the better the model, the more useful you'll find it in the future.  (The one I have now - I've had for almost 10 years, and if someone hadn't torched my shop, I'd still be using models I'd had for years before that.)
  2. Make a RF sniffer probe for it.  VERY useful for troubleshooting radios.  You can use on-the-air signals or some other source (mentioned later).
  3. A directional wattmeter (aka SWR meter) - you can make one of these if need be - even make one that works with the DVM.  This is important - because a poor match puts transmitters in jeopardy.  It's not about "Maximum signal out!!!", it protects the finals from being overstressed!!!
  4. The next on the list: a 50 ohm dummy load.  VERY important - you can make one (just don't use wirewound resistors!).  I'd encourage looking at kits, by the way - if you have any experience at all with soldering (start with simple kits and you can develop adequate skill rather fast).

Less critical but worth having.  Kits, by the way, do work... and you might know someone who has an old scope lying around that they don't have a use for.  I've got a couple of pieces of equipment I built from kits - and have considered others.

  1. Here is where I'd put a scope - they may not be essential, but if you have any experience at all with them, they're that useful (make sure you have bandwidth in excess of the signal you expect to check).
  2. Almost as important - a signal source.  There are DDO kits available that are inexpensive and they do an adequate job (although the signal isn't that clean/pure).
  3. Make or buy a step attenuator (for the signal source) - if you don't luck out and find one.
  4. Here is where I'd put something like a VNA or other antenna checker.
  5. It goes on from there.  I'd even suggest something like a "grid dipper" or similar - they are VERY useful, especially when checking things like toroids and caps.  I used to have one - and miss it.
  6. Here's another good one - for checking many components.  It's called a "zener Sweeper" - and I used to have one.  There may be other little things like that.
  7. I thought I'd mention a RF bridge.  I bought a wide-band bare-bones one from China, and I'd previously built a dBm meter (combined chip and components with an arduino).  You can combine these with a DDO signal generator and do all sorts of neat stuff - even synthesize something resembling a dipper!
  8. The rest is per personal preference.  One more thing - don't stint on the soldering iron.  Get a good one (you don't have to break the bank to find a good one... temperature controlled and grounded).  Ditto for small tools - a good wire nipper is very important (especially for kits).

VERY important - do your best to get manuals (including service if available) for everything!!!  They can save tons of headache and heartache!

Good luck... and I hope this helps.

Bob

N4FBZ (First licensed 1980, General Radiotelephone {commercial radios} 1981.)


On 5/17/20 10:59 AM, ponton.leo@... wrote:

Very off topic. My mind is wandering since passing my foundation, getting my call sign and now waiting for a radio. The Baofeng I ordered at the beginning of April didn’t arrive (woop!) and I got a refund. The next day delivery FT-65 to replace it which I ordered on Thursday is coming on Monday. My uBitx is awaiting a despatch window. My CW isn’t good enough to use my Forty-9er yet. I can’t afford a FT-817.


So, I’m tinkering with circuits, arduino and so on. Of course whenever I google something there’s an oscilloscope in the article. Since I was a kid I thought I needed one but they’re pricey. Does anybody know....are those twenty-odd quid digital things any good? e.g. JYE Tech DSO138 Mini Digital Oscilloscope. I’ve heard good things about the NanoVNA and I wondered if these little ‘scopes are reasonable in the same way.

Or maybe I’d be better getting and old style big box scope from eBay and hope it works (“Spares only, turns on, but no way to test it” is the standard disclaimer)

Better still, what do people recommend for basic test equipment?

 

 



Re: Getting enough power to check SWR with BITx40

 

Scott,

For years I've been using a free app for my iPhone called Tone Generator, it comes up outputting a 1000hz sine wave tone, I just put it by the mic and key up then make my tuner adjustments. It's been working great for a long time.

Joel
N6ALT


Re: LIVE icon added to bitxmap.com

JohnR
 

I am sorry I may have missed something or just can't figure it out. How do we go "live" on the map or change an icon or what do each icon mean. Is there a legend or instructions I am missing? I made it on the map.at least.
KG4VHV
john

--

“A single light can banish the darkness”

Lux e tenebris 

"A fool stares at the finger that points at the moon"
I Ching




Re: #calibration #v5 #calibration #v5

Evan Hand
 

All of you are giving me more credit than is due.  If you would read as many of the posts here as I do, you would gain the same or more knowledge.  It is the advantage of being retired (lots of free time).

There are others on this board that are more knowledgable than I, they have other jobs or commitments such that I get in the first post.  I would head anyone that does provide another point of view, as they may have the first-hand experience that I do not.  I do try to point out my limits so that if another does provide input you can judge for yourself.

Again, Thank you for the kind words.
73
Evan
AC9TU


Re: Getting enough power to check SWR with BITx40

Scott
 

Thanks to every one that replied to my question.  I now understand that for single side band the power should be very low (or zero) with no microphone input (which is consistent with my observations).  My son and I can work out the details of how to get a signal into the radio for making the measurements.  I will take a look at implementing a CW mod for the BITx40, I have seen instructions for this online. Introducing a tone into the mic might get my son up and running the fastest.

Thanks,
Scott


Re: Getting enough power to check SWR with BITx40

Arv Evans
 

Scott

If I understand what you are saying, this may be a misunderstanding of how SSB works.  
Ideally there would be no, or minimal, power output without audio input from the mike.
Audio input unbalances the balanced modulator and allows modulated carrier to go 
to the transmit stages.  Old-school way of testing SSB output was to use a two-tone 
audio oscillator to generate speech-like tones into the mike input.  For a pure carrier 
output you can insert a single audio tone into the mike input.  This will give you a CW-like 
output that is offset from the carrier frequency by the tone frequency.

Arv  K7HKL
_._


On Sun, May 17, 2020 at 8:45 AM Scott <sskroch@...> wrote:
My son purchased a BITx40 and we thought it would be a good idea to check the SWR of his home made antenna before transmitting.
 
The problem we have run into is that his BITx40 only puts out a fraction of a Watt of power (.016 W) unless we are speaking into the microphone.  We are not able to use our SWR bridge with the low power.
 
1. Is this normal for a BITX40?
 
2. Assuming this is normal, is there a standard way to increase the power to the antenna for these types of measurements?  (I suppose we could set up a speaker next to the microphone to give consistent white noise or tone input.) 
 
Power output was determined by taking voltage measurements with a multimeter on the output leads of a 50 Ohm dummy load.
1.05V without speaking into the microphone (1.05V)^2 / 50 Ohm *.707 = .016 W (RMS power)
18V Loudly speaking into the microphone (18V)^2 / 50 Ohm *.707 = 4.58 W (RMS power)
 
Thanks,
Scott


Re: Getting enough power to check SWR with BITx40

Satish Chandorkar
 

Scott
You have not stated how you measured power across your dummy load.
Was it a RF probe or oscilloscope or anything else
Without knowing of this whatever calculations you are stating has no meaning

Satish
VU2SNK


On Sun, May 17, 2020 at 9:09 PM Bill Cromwell <wrcromwell@...> wrote:
Just as a suggestion you might use something like fldigi in it's CW mode
and send the Morse signal that way. You may have to include a VOX switch
id the BitX doesn't have that. It can be included in the interface
to/from the computer sound card. It may be needed for using the digital
modes anyway.

Using the push to talk in SSB with no audio input should produce no
output just at the  others have said. Between the balanced modulator and
the filter you should be in the microwatt (or low millwatt) range with
the carrier leakage.

73,

Bill  KU8H


On 5/17/20 11:18 AM, Evan Hand wrote:
> Scott,
> Yes, it is normal for all SSB transmitters to have no power out without
> any audio.  It is why they are more efficient than AM transmitters.  For
> most trancievers there is a CW mode that allows you to send a pure
> carrier when the CW key is pressed.  That is how I do tuning/SWR checks
> with my uBITX.
>
> I checked the BITX40 schematic and found no CW key input.  The only way
> that I can think of to do the equivalent would be to use a tone
> generator to feed either one or two tones into the microphone input. 
> Alternatively, you could use a tone generation program on a PC and hold
> the mic near the speaker to generate the tone.
>
> Here is a single tone generator that is free
> https://www.microsoft.com/en-us/p/tone-generator/9wzdncrdhjqn?activetab=pivot:overviewtab
> I would recommend using 1,000 Hrz as the tone.
>
> An actual owner of a BITX40 may have another way, as maybe there is a
> way to set up the transceiver for CW.
>
> 73
> Evan
> AC9TU
>

--
bark less - wag more




Re: #calibration #v5 #calibration #v5

Don - KM4UDX
 

Evan is one of the best and most helpful  uBITX diagnosticians in the known universe..

I too follow his posts. I read them like a master class. 

Don
Km4udx


Re: Test equipment recommendations

Evan Hand
 

For me, the basic is:
1 - DMM
2 - An SWR/Power meter
3 - A 100Mhz or better oscilloscope
4 - A PC

Nice to have if you are going to do surgery, PA mods, or antenna experiments:
1 - An SDR Play RSP1A with a -50 DB tap and step attenuator to use as a Spectrum Analyzer (SA) 
2 - NanoVNA or Antuino (from HF Signals)
3 - 50MHz signal generator

Really nice to have:
1 - 2 GHz spectrum analyzer (Sigelent or Rigol)

All of the DSO Oscilloscopes that I have seen are only good to 1 MHz or so.  You really need the 100 MHz to do testing on a superheterodyne transceiver like the uBITX.

I have been pleasantly surprised by the flexibility and usefulness of the SDR Play RSP1A as a SA.  Of course, I would really like a Sigelent or Rigol SA, just not ready to spend $1,000+.

Above are my thoughts, others may be different, and YMMV.
Good Luck
73
Evan
AC9TU


Re: Test equipment recommendations

Bill Cromwell
 

Hi,

The nanVNA is not going to serve you as a scope. Have you considered building some (or all) of your own test/measurement gear? In my early teens such things were beyond my reach so my first measurement gear was a homebrewed V-O-M in a cigar box. If I could do things like that so can *you*. There have been homebrew scope designs over the years in various publications. One was in "73 Magazine" in two issues in the 1970s and the article to look for is "Eyes For Your Shack". The entire run of "73 Magazine" is available online. Google can be your friend. You could look at that article and any others you can find for inspiration to build your own.

As for eBay and those disclaimers avoid those like the plague (unless you only want a box of parts). Get something from a seller with good ratings and an assurance that the unit is not junk. Not everybody on eBay is a scoundrel.

I hope this helps.

73,

Bill KU8H

On 5/17/20 10:59 AM, ponton.leo@... wrote:
Very off topic. My mind is wandering since passing my foundation, getting my call sign and now waiting for a radio. The Baofeng I ordered at the beginning of April didn’t arrive (woop!) and I got a refund. The next day delivery FT-65 to replace it which I ordered on Thursday is coming on Monday. My uBitx is awaiting a despatch window. My CW isn’t good enough to use my Forty-9er yet. I can’t afford a FT-817.
So, I’m tinkering with circuits, arduino and so on. Of course whenever I google something there’s an oscilloscope in the article. Since I was a kid I thought I needed one but they’re pricey. Does anybody know....are those twenty-odd quid digital things any good? e.g. JYE Tech DSO138 Mini Digital Oscilloscope. I’ve heard good things about the NanoVNA and I wondered if these little ‘scopes are reasonable in the same way.
Or maybe I’d be better getting and old style big box scope from eBay and hope it works (“Spares only, turns on, but no way to test it” is the standard disclaimer)
Better still, what do people recommend for basic test equipment?
--
bark less - wag more


Re: Getting enough power to check SWR with BITx40

Bill Cromwell
 

Just as a suggestion you might use something like fldigi in it's CW mode and send the Morse signal that way. You may have to include a VOX switch id the BitX doesn't have that. It can be included in the interface to/from the computer sound card. It may be needed for using the digital modes anyway.

Using the push to talk in SSB with no audio input should produce no output just at the others have said. Between the balanced modulator and the filter you should be in the microwatt (or low millwatt) range with the carrier leakage.

73,

Bill KU8H

On 5/17/20 11:18 AM, Evan Hand wrote:
Scott,
Yes, it is normal for all SSB transmitters to have no power out without any audio.  It is why they are more efficient than AM transmitters.  For most trancievers there is a CW mode that allows you to send a pure carrier when the CW key is pressed.  That is how I do tuning/SWR checks with my uBITX.
I checked the BITX40 schematic and found no CW key input.  The only way that I can think of to do the equivalent would be to use a tone generator to feed either one or two tones into the microphone input. Alternatively, you could use a tone generation program on a PC and hold the mic near the speaker to generate the tone.
Here is a single tone generator that is free
https://www.microsoft.com/en-us/p/tone-generator/9wzdncrdhjqn?activetab=pivot:overviewtab
I would recommend using 1,000 Hrz as the tone.
An actual owner of a BITX40 may have another way, as maybe there is a way to set up the transceiver for CW.
73
Evan
AC9TU
--
bark less - wag more


Re: Getting enough power to check SWR with BITx40

Evan Hand
 

Scott,
Yes, it is normal for all SSB transmitters to have no power out without any audio.  It is why they are more efficient than AM transmitters.  For most trancievers there is a CW mode that allows you to send a pure carrier when the CW key is pressed.  That is how I do tuning/SWR checks with my uBITX.  

I checked the BITX40 schematic and found no CW key input.  The only way that I can think of to do the equivalent would be to use a tone generator to feed either one or two tones into the microphone input.  Alternatively, you could use a tone generation program on a PC and hold the mic near the speaker to generate the tone.

Here is a single tone generator that is free
https://www.microsoft.com/en-us/p/tone-generator/9wzdncrdhjqn?activetab=pivot:overviewtab
I would recommend using 1,000 Hrz as the tone.

An actual owner of a BITX40 may have another way, as maybe there is a way to set up the transceiver for CW.

73
Evan
AC9TU


Re: Getting enough power to check SWR with BITx40

Gordon Gibby
 

When doing single side band, you are not supposed to see power when not speaking. 

The solution for that is either to use key down Morse code, or inject a tone into your microphone.   

For years, amateur radio operators have simply press the Morse code key down to generate a carrier output


On May 17, 2020, at 11:01, Dale Parfitt <PARINC1@...> wrote:



Hi Scott,

Ideally, there would be zero  output w/o voice in SSB mode. Use  CW mode, not SSB.

 

Regards & have fun.

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Scott
Sent: Sunday, May 17, 2020 10:45 AM
To: BITX20@groups.io
Subject: [BITX20] Getting enough power to check SWR with BITx40

 

My son purchased a BITx40 and we thought it would be a good idea to check the SWR of his home made antenna before transmitting.
 
The problem we have run into is that his BITx40 only puts out a fraction of a Watt of power (.016 W) unless we are speaking into the microphone.  We are not able to use our SWR bridge with the low power.
 
1. Is this normal for a BITX40?
 
2. Assuming this is normal, is there a standard way to increase the power to the antenna for these types of measurements?  (I suppose we could set up a speaker next to the microphone to give consistent white noise or tone input.) 

 

Power output was determined by taking voltage measurements with a multimeter on the output leads of a 50 Ohm dummy load.
1.05V without speaking into the microphone (1.05V)^2 / 50 Ohm *.707 = .016 W (RMS power)
18V Loudly speaking into the microphone (18V)^2 / 50 Ohm *.707 = 4.58 W (RMS power)
 
Thanks,
Scott


Re: Getting enough power to check SWR with BITx40

Dale Parfitt
 

Hi Scott,

Ideally, there would be zero  output w/o voice in SSB mode. Use  CW mode, not SSB.

 

Regards & have fun.

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Scott
Sent: Sunday, May 17, 2020 10:45 AM
To: BITX20@groups.io
Subject: [BITX20] Getting enough power to check SWR with BITx40

 

My son purchased a BITx40 and we thought it would be a good idea to check the SWR of his home made antenna before transmitting.
 
The problem we have run into is that his BITx40 only puts out a fraction of a Watt of power (.016 W) unless we are speaking into the microphone.  We are not able to use our SWR bridge with the low power.
 
1. Is this normal for a BITX40?
 
2. Assuming this is normal, is there a standard way to increase the power to the antenna for these types of measurements?  (I suppose we could set up a speaker next to the microphone to give consistent white noise or tone input.) 

 

Power output was determined by taking voltage measurements with a multimeter on the output leads of a 50 Ohm dummy load.
1.05V without speaking into the microphone (1.05V)^2 / 50 Ohm *.707 = .016 W (RMS power)
18V Loudly speaking into the microphone (18V)^2 / 50 Ohm *.707 = 4.58 W (RMS power)
 
Thanks,
Scott


Test equipment recommendations

Leo
 

Very off topic. My mind is wandering since passing my foundation, getting my call sign and now waiting for a radio. The Baofeng I ordered at the beginning of April didn’t arrive (woop!) and I got a refund. The next day delivery FT-65 to replace it which I ordered on Thursday is coming on Monday. My uBitx is awaiting a despatch window. My CW isn’t good enough to use my Forty-9er yet. I can’t afford a FT-817.


So, I’m tinkering with circuits, arduino and so on. Of course whenever I google something there’s an oscilloscope in the article. Since I was a kid I thought I needed one but they’re pricey. Does anybody know....are those twenty-odd quid digital things any good? e.g. JYE Tech DSO138 Mini Digital Oscilloscope. I’ve heard good things about the NanoVNA and I wondered if these little ‘scopes are reasonable in the same way.

Or maybe I’d be better getting and old style big box scope from eBay and hope it works (“Spares only, turns on, but no way to test it” is the standard disclaimer)

Better still, what do people recommend for basic test equipment?

 

 


Re: Getting enough power to check SWR with BITx40

R. Tyson
 

Hi Scott,
Sounds about right. The mic. is usually not very good and does better with either a replacement or mic. amp. to boost it up a bit.

Why not set up the antenna tuning by using the CW setting ? It will give a more consistent output than voice and make it easier to do.

Reg             G4NFR


Re: Slowing down Tx to Rx

Evan Hand
 

Reg,

The value delays the change from transmitting back to receive. As I stated in the prior message, it is in milliseconds, so you would need to enter a value that is large to note a difference. Try 2000 for a 2-second delay.

I am not aware of a way to delay the start of transmission (from RX to TX) if that is what you want.  You could add it to the Nano program.

73
Evan
AC9TU