Topics

Test equipment recommendations

Leo
 

Thanks for the heads up Jack. I hadn’t spied that you were the author of that article! It’ll be an interesting experiment that will hopefully contribute to my Intermediate licence. 

i snagged a scope for £50 - don’t know yet if it will work. I’ll also be building test equipment such as RF tracer, sig gen etc. I’m also planning a SWR / power meter with a stockton bridge and a nano. Fun fun fun. 

Jack, W8TEE
 

Hi Leo:

You may have to do some adjustments on the 49-er article as we used an AD9850 which generates a sine wave, where the Si5153 is square wave. Still, it's a fun project and works surprisingly well.

Jack, W8TEE

On Wednesday, May 20, 2020, 6:14:40 PM EDT, ponton.leo@... <ponton.leo@...> wrote:


Wow! A mountain of great advice - thank you all so much. 

i have a RTL SDR V3 dongle which works pretty well and covers HF without an up converter. I can see on its own it will be a great diagnostic tool. I’m not scared of electronics having tinkered for many years starting with an HAC single valve receiver and a very long wire - Radio Moscow, Radio Prague and Voice of America seemed to swamp everything else. 

I’ll probably put the ‘scope on the back burner again although there were some good suggestions I’ll be looking into.

For the rest I’ll research and built and hack and modify. As a career programmer I can Arduino and I expect this to be a mainstay. I’ve just received a SI5351 from China and I have an OLED display so you can guess what I’ll be making. I found an ARRL article (QST?) on hacking the Chinese version Forty-9er to use a VFO and I have that kit in my drawer so that’s going to be a project soon.
once again thanks for all of your advice.

 


--
Jack, W8TEE

Doug W
 

On Wed, May 20, 2020 at 05:44 PM, Doug W wrote:
In addition to this list, it sounds like you would also enjoy https://groups.io/g/SoftwareControlledHamRadio
I forgot to mention https://groups.io/g/HBTE
 
--
www.bitxmap.com

Doug W
 

On Wed, May 20, 2020 at 05:14 PM, <ponton.leo@...> wrote:
For the rest I’ll research and built and hack and modify. As a career programmer I can Arduino and I expect this to be a mainstay. I’ve just received a SI5351 from China and I have an OLED display so you can guess what I’ll be making. I found an ARRL article (QST?) on hacking the Chinese version Forty-9er to use a VFO and I have that kit in my drawer so that’s going to be a project soon.
In addition to this list, it sounds like you would also enjoy https://groups.io/g/SoftwareControlledHamRadio

As for a scope, I picked up a Tektronix 2235 on ebay from a reputable seller for probably less than it cost to make the box it came in when it was new.
 
--
www.bitxmap.com

Leo
 

Wow! A mountain of great advice - thank you all so much. 

i have a RTL SDR V3 dongle which works pretty well and covers HF without an up converter. I can see on its own it will be a great diagnostic tool. I’m not scared of electronics having tinkered for many years starting with an HAC single valve receiver and a very long wire - Radio Moscow, Radio Prague and Voice of America seemed to swamp everything else. 

I’ll probably put the ‘scope on the back burner again although there were some good suggestions I’ll be looking into.

For the rest I’ll research and built and hack and modify. As a career programmer I can Arduino and I expect this to be a mainstay. I’ve just received a SI5351 from China and I have an OLED display so you can guess what I’ll be making. I found an ARRL article (QST?) on hacking the Chinese version Forty-9er to use a VFO and I have that kit in my drawer so that’s going to be a project soon.
once again thanks for all of your advice.

 

Mark Muller
 

One suggestion: perhaps obvious given the others, perhaps not. Maybe you are near some sort of ham club, or at least within driving distance. While there may be a prohibition on swap meets, maybe you can drive to another ham's house? If so, maybe you an join a local club online, and ask the club moderator to send out an email request to the members, to see if anyone has a working analog, or inexpensive digital scope sitting on the shelf that they want to sell; or perhaps someone in the club knows of one that might be for sale from a school or non-member. Let them know approximately what you want in the way of performance, and what you want to spend. Who knows what you might find??? 

Robert D. Bowers
 

That sounds interesting, and would be a worthwhile thing to have (even for someone new, if the software is relatively easy to use and understand).  I'm used to (in my head) "stitching together" the results from my dongle via GQRX, but having software to do it would be great!  (I picked up a broken sweep generator and fixed it, so I have that capability to a degree already, but at the same time that could help in some instances!)

Thanks for bringing that up!


On 5/18/20 11:37 AM, Scott McDonald via groups.io wrote:
Given the modeling comments I may regret suggesting this, but as lots of folks have some of the less expensive SDRs, the free software that stitches multiple frequency ranges together to perform as a spectrum analyzer is a pretty cool piece of test kit.

A bit of learning required, but being able to look at the spectrum from your transmitter, or the output of a mixer module, really can speed along learning radio.  Much more intuitive than a scope for RF stuff to me.

I'm most familiar with the free software available for the RSP series SDRs, and have used that with a cheapie noise generator for lots of filter analysis, and am very happy with it.  I believe there is similar software available for dongles as well.  Slower than a real spectrum analyzer for sure, and often some bugs and spurs, but pretty amazing for the price of a free download.

Worth a thought if you already have a cheapie SDR.  

I would NOT do it with a more expensive SDR unless you are darn careful tho :)

Cheers, Scott ka9p


-----Original Message-----
From: Robert D. Bowers <n4fbz@...>
To: BITX20@groups.io
Sent: Mon, May 18, 2020 9:41 am
Subject: Re: [BITX20] Test equipment recommendations

You talk about a steep learning curve for the NanoVNA and then suggest MODELING SOFTWARE?  You do know that doesn't make sense - it could overwhelm someone in a hurry?

Let a new ham learn what they want to learn and when they're ready to learn - in order to pass the test (unless it's really been watered down even more since I got my Extra) they have to have some understanding of the basics already.  You have to build on a foundation - not start erecting the superstructure while the foundation is still being poured!

I'd suggest rather than modeling software, using the ARRL Antenna book or something similar.  That's appropriate not only for someone new to radio, but also useful even for experienced hams.  It also helps to lay a good foundation that can be built on.

Modeling can come later - at their own pace and if they choose.  (The VNA also may be a bit much, although the more a learns, the more valuable such a tool becomes.  That's why a directional wattmeter/SWR bridge is suggested.  Start simple and build up.)


On 5/18/20 9:38 AM, flatpickn via groups.io wrote:
If your interest aligns with this:
The NanoVNA is a nice piece of equipment for not a lot of money. I have an H model.
It does have a steep learning curve which would be true of any VNA.
Build yourself a wire antenna. Make it cheap, use speaker wire from the hardware store. Download the free copy of Eznec and model the antenna in it. Use the Nano to tune it and compare it to the model.
When your done, you'd have a good fundamental  understanding of antennas, a beginning knowledge of antenna analysis,  and you'll know the vna well enough to tackle other vna work like evaluating baluns and circuit impedences.
There's plenty of resources on the internet to help you figure it out.

Scott McDonald
 

Given the modeling comments I may regret suggesting this, but as lots of folks have some of the less expensive SDRs, the free software that stitches multiple frequency ranges together to perform as a spectrum analyzer is a pretty cool piece of test kit.

A bit of learning required, but being able to look at the spectrum from your transmitter, or the output of a mixer module, really can speed along learning radio.  Much more intuitive than a scope for RF stuff to me.

I'm most familiar with the free software available for the RSP series SDRs, and have used that with a cheapie noise generator for lots of filter analysis, and am very happy with it.  I believe there is similar software available for dongles as well.  Slower than a real spectrum analyzer for sure, and often some bugs and spurs, but pretty amazing for the price of a free download.

Worth a thought if you already have a cheapie SDR.  

I would NOT do it with a more expensive SDR unless you are darn careful tho :)

Cheers, Scott ka9p


-----Original Message-----
From: Robert D. Bowers <n4fbz@...>
To: BITX20@groups.io
Sent: Mon, May 18, 2020 9:41 am
Subject: Re: [BITX20] Test equipment recommendations

You talk about a steep learning curve for the NanoVNA and then suggest MODELING SOFTWARE?  You do know that doesn't make sense - it could overwhelm someone in a hurry?

Let a new ham learn what they want to learn and when they're ready to learn - in order to pass the test (unless it's really been watered down even more since I got my Extra) they have to have some understanding of the basics already.  You have to build on a foundation - not start erecting the superstructure while the foundation is still being poured!

I'd suggest rather than modeling software, using the ARRL Antenna book or something similar.  That's appropriate not only for someone new to radio, but also useful even for experienced hams.  It also helps to lay a good foundation that can be built on.

Modeling can come later - at their own pace and if they choose.  (The VNA also may be a bit much, although the more a learns, the more valuable such a tool becomes.  That's why a directional wattmeter/SWR bridge is suggested.  Start simple and build up.)


On 5/18/20 9:38 AM, flatpickn via groups.io wrote:
If your interest aligns with this:
The NanoVNA is a nice piece of equipment for not a lot of money. I have an H model.
It does have a steep learning curve which would be true of any VNA.
Build yourself a wire antenna. Make it cheap, use speaker wire from the hardware store. Download the free copy of Eznec and model the antenna in it. Use the Nano to tune it and compare it to the model.
When your done, you'd have a good fundamental  understanding of antennas, a beginning knowledge of antenna analysis,  and you'll know the vna well enough to tackle other vna work like evaluating baluns and circuit impedences.
There's plenty of resources on the internet to help you figure it out.

Robert D. Bowers
 

You talk about a steep learning curve for the NanoVNA and then suggest MODELING SOFTWARE?  You do know that doesn't make sense - it could overwhelm someone in a hurry?

Let a new ham learn what they want to learn and when they're ready to learn - in order to pass the test (unless it's really been watered down even more since I got my Extra) they have to have some understanding of the basics already.  You have to build on a foundation - not start erecting the superstructure while the foundation is still being poured!

I'd suggest rather than modeling software, using the ARRL Antenna book or something similar.  That's appropriate not only for someone new to radio, but also useful even for experienced hams.  It also helps to lay a good foundation that can be built on.

Modeling can come later - at their own pace and if they choose.  (The VNA also may be a bit much, although the more a learns, the more valuable such a tool becomes.  That's why a directional wattmeter/SWR bridge is suggested.  Start simple and build up.)


On 5/18/20 9:38 AM, flatpickn via groups.io wrote:
If your interest aligns with this:
The NanoVNA is a nice piece of equipment for not a lot of money. I have an H model.
It does have a steep learning curve which would be true of any VNA.
Build yourself a wire antenna. Make it cheap, use speaker wire from the hardware store. Download the free copy of Eznec and model the antenna in it. Use the Nano to tune it and compare it to the model.
When your done, you'd have a good fundamental  understanding of antennas, a beginning knowledge of antenna analysis,  and you'll know the vna well enough to tackle other vna work like evaluating baluns and circuit impedences.
There's plenty of resources on the internet to help you figure it out.

flatpickn@...
 

If your interest aligns with this:
The NanoVNA is a nice piece of equipment for not a lot of money. I have an H model.
It does have a steep learning curve which would be true of any VNA.
Build yourself a wire antenna. Make it cheap, use speaker wire from the hardware store. Download the free copy of Eznec and model the antenna in it. Use the Nano to tune it and compare it to the model.
When your done, you'd have a good fundamental  understanding of antennas, a beginning knowledge of antenna analysis,  and you'll know the vna well enough to tackle other vna work like evaluating baluns and circuit impedences.
There's plenty of resources on the internet to help you figure it out.

Curt
 

I suggest slowly figuring what you really need, watching for inexpensive club and merchant kits. A xtal oscillator makes a great signal generator or consider a pll signal generator from qrp labs or usr signals on the air. A qrp power meter is useful, but a diode detector and dvm can work also. Don't work too hard to find a used 100 mhz scope, one can be had cheaply if you are patient. Enjoy the journey.

Curt wb8yyy

Robert D. Bowers
 

No.  I got it off of eBay.  I'd have to look it up (it's out in my shop).  It came from China as I remember.

I've got a couple of those $10-$15 Radio Shack multimeters - one out back, and one in the tool box in my van.  They'll do 90% of what you usually need one for (especially with probes like for RF snooping).  In my shop/home lab, I needed one with additional functions - like peak hold and digital output - which gets occasional use.  For more really complicated stuff I turn to my good digitizer scope.  IMO, a good meter is something that as you get more experienced, the more you'll appreciate the 'extras' - especially if you don't have access to the really good equipment.  Mine isn't the best unit available, but it's accurate and precise enough for what I do - and it has adequate safety stuff built in. 

I probably grab the meter about 80% of the time... my scopes come next (probably 10%), followed by the other equipment.

On 5/17/20 8:10 PM, Reed N wrote:
Hi Bob,

For home/hobby use, I have a Best DT-9205M. It's not a high quality multimeter, but it measures AC and DC voltage and current, resistance, and capacitance. It's good enough for order of magnitude capacitance (is this a 0.1uF, or 1uF?), and reasonable on DC voltage readings. It's unfused on the current input, so I never use it for high current systems - that's just asking for trouble. For high current stuff, I borrow the high quality multimeters (with all the bells and whistles, like min/max hold, counters, and such) from work, but I can't remember the last time I needed to do that. I don't think buying a quality (expensive) multimeter would be a bad idea, and you're absolutely right about them lasting a LONG time (with proper care), but also don't think that it's necessary to buy something like a Fluke 289, BK Precision 393, or 121GW straight out of the gate.

I whole-heartedly agree with you about reading and following your equipment's specs! That's what I was hoping to convey with the "know your tools' limitations" bit.

Do you have a link to whatever kit you bought for the HF upconversion?


Reed

Reed N
 

Hi Bob,

For home/hobby use, I have a Best DT-9205M. It's not a high quality multimeter, but it measures AC and DC voltage and current, resistance, and capacitance. It's good enough for order of magnitude capacitance (is this a 0.1uF, or 1uF?), and reasonable on DC voltage readings. It's unfused on the current input, so I never use it for high current systems - that's just asking for trouble. For high current stuff, I borrow the high quality multimeters (with all the bells and whistles, like min/max hold, counters, and such) from work, but I can't remember the last time I needed to do that. I don't think buying a quality (expensive) multimeter would be a bad idea, and you're absolutely right about them lasting a LONG time (with proper care), but also don't think that it's necessary to buy something like a Fluke 289, BK Precision 393, or 121GW straight out of the gate.

I whole-heartedly agree with you about reading and following your equipment's specs! That's what I was hoping to convey with the "know your tools' limitations" bit.

Do you have a link to whatever kit you bought for the HF upconversion?


Reed

Robert D. Bowers
 

Laugh!!!   I suggested a good meter because the ones I was thinking about had other useful functions like cap testing and better tolerance of spikes (plus the safety features you mentioned).  To that I'd add that multimeters as a general rule don't like HF (guess how I know)!  Some have a frequency counter function built in - but the models I've seen with that were limited in bandwidth - and as I'd learned, that maximum frequency and AC voltage IS the limit. Another suggestion to add - remember the specs and try to avoid exceeding them!

I'd forgotten the general coverage receiver.  Thanks for bringing that up.

As far as SDR, you can buy a bare-bones upconverter now that works pretty well, for not that much money.  I've got one - board and components only, but it's sensitive, rather good at rejecting signals above 30mhz, and doesn't seem to radiate much when used. (So far I've not seen any ghost signals from the upconverter - and I do watch for them.)

Bob

On 5/17/20 6:20 PM, Reed N wrote:
There's already a lot of good recommendations here, but thought I'd add my 2 cents.

Reed N
 

There's already a lot of good recommendations here, but thought I'd add my 2 cents.

I am in the fortunate position of having access to decent test equipment via my work when needed. However, I rarely actually take advantage of this, as for most hobby stuff, I can make due with the hobby grade stuff I have at home. One of the most important skills as a tinkerer is to learn how your tools work, so you can use them to their full potential, but perhaps more importantly, so that you know your tools' limitations and either work around them, or know when to buy better tools.

The Internet is an extremely valuable piece of "test equipment". If you look around here, or any of the other numerous radio forums, you'll find tons of examples of people describing basic symptoms, which others have already encountered, and can suggest fixes for, without ever using a physical diagnostic tool. However, the Internet by itself is also very limited in what it can test, so if you have an uncommon or non-obvious problem, it can't help much without additional test tools.

A cheap ($10-20USD) multimeter is by far the best testing per dollar investment. The one I have at home is known to be somewhat inaccurate, but has been good enough for diagnosing my hobby stuff for many years now. The continuity buzzer is probably the feature I use most anyway, to find shorts or opens where they shouldn't be. You can spend hundreds on a good multimeter, but do you REALLY need values accurate to 5 digits, or can you get by with 1-2 digits and a little error? You might need the accuracy if you're doing matching for a mixer, or precision resistor measurements, but most of the time I suspect not. The main thing to be careful with on the cheap end is high voltage or current, since many cheap models skimp on safety features like fuses. If you're working QRP or microcontroller electronics, this shouldn't be a big problem, but if you're working on high power rigs, then you'll want to make sure your multimeter has the proper fuses and isolation.

A SWR/power meter is useful for every-day operation. I have one built into my antenna matcher, and use it so much that I hardly think of it as test equipment, even though it obviously is. While an antenna analyzer can help you with SWR (discussed below), the forward power meter part lets you measure your actual output. Turns out SWR doesn't matter if your transmitter isn't actually outputting anything!

For general RF detection, an LED and a diode make for a super cheap indicator. Take a look at https://www.youtube.com/watch?v=V5SMF9p-4Q0 for example.

A dummy load is also piece test equipment I often take for granted. It's great for verifying transmitter stuff without actually broadcasting (appreciably), can be used in conjunction with a power meter to verify full power output without worrying about SWR, and if you have another radio, the leaked power on my dummies is often large enough to be detected by an adjacent receiver for further validation.

For radio use, it's a toss up for me if the next best investment is an oscilloscope, or a network/antenna analyzer. If you're planning on doing lots of antenna design or tweaking, then the analyzer would serve you better. If you're planning on spending more time working on rigs or other electronics, then the oscilloscope probably is the better choice. Of course, if you can afford both, then even better.

For oscilloscopes, as mentioned by others, the key is to have enough bandwidth for the signals you actually care about. The DSO138 you mentioned isn't necessarily a bad choice, as long as all of your signals of interest are in the audio frequencies, or are slow-ish digital (like Arduino stuff usually is). It's low price is attractive, but it's actually significantly more expensive in Hz per dollar than the "real" entry level oscilloscopes out there (200kHz/$10 for the cheapest DSO138 kit I see = 20kHz/$1, vs e.g. Hantek 2C42's 40MHz/$104 = 385kHz/$1), and is not at all competitive in performance. I have a XMEGA-based 200kHz (2MSPS) oscilloscope that I bought a number of years back, and it definitely has helped me solve problems that my multimeter just can't. Having even a 200kHz time domain can be incredibly useful, so if you have a tight budget, something like the DSO138 could be worth while. However, for analyzing RF, you'll need an oscilloscope that has a much larger analog bandwidth. The uBiTX IF goes up to 75MHz (officially, more if you ask the Si55351 to :P), so if you plan to work on the uBiTX's RF chain at all frequencies, you should consider buying a scope capable of ~75MHz analog bandwidth. As Robert mentioned, DSOs are sometimes advertised with their sampling frequency, rather than analog bandwidth. Shannon/Nyquist tells us we need at least 2x sampling for a given frequency, so you'd need an absolute minimum of 150MSPS to get 75MHz analog bandwidth measurements, but realistically you should aim for higher samples per second so that you can actually see the shape of the wave. Analog oscilloscopes don't have discrete samples, so as Ashhar pointed out, you can use them at higher frequencies - they'll just measure lower amplitudes than actually are present past their designated bandwidth. I would agree with Bill, and advise against purchasing anything on eBay that's not listed as being in working condition with pictures of sample traces, unless you're ready to spend time diagnosing and fixing it yourself, which will be particularly difficult if you don't already have a working oscilloscope. Randy's suggestion of looking at hamfests is a good one.

For the antenna analyzer, the NanoVNA you mentioned is a great tool for the money. It's capable of all the stuff the more expensive units are (e.g. MFJ's SWR-584C, or RigExpert offerings), but the NanoVNA has a bit steeper of a learning curve than those more expensive options too. K7TRF wrote up a nice short comparison recently over at https://forums.qrz.com/index.php?threads/antenna-analyzer-so-many-choices.689265/#post-5335185 . One thing to watch out for with the NanoVNA specifically is all of the clones. I'd strongly recommend buying directly from one of the NanoVNA's developer's links (such as hugen79 or flyoob
) to ensure you get one that doesn't take any shortcuts, and directly benefits the parties responsible for the tool development.

Once you have most of the equipment above, an SDR would probably be my next recommendation. The normal RTL dongles won't work at HF (though you can find some RTL dongles with HF upconverters built in), but there are a good number of options in the ~$100USD range. There are tons of things you can do with SDR, but as a test tool specifically for the uBiTX, I've found it most useful for calibration of the oscillator, and verification of signal output in various modes. They can also work as a windowed spectrum analyzer, useful for finding unwanted harmonics or spurs, or measure relative power output.


Reed

Ashhar Farhan
 

Even a 20 mhz scope is good enough. The old analog, crt scopes dont shutter down beyond their operating frequency, they remain usable to almost twice the frequency. 
These can be picked up for a few dollars. The other really useful test instrument is a general coverage superher receiver. You can build one quickly. Keep no front end filter so that it tunes a wide range with a wide range vfo. This becomes your manual spectrum analyzer.

On Mon 18 May, 2020, 1:34 AM Gigabyte, <steven.b.hoff@...> wrote:
The speed of most of those little scopes is not fast enough for a lot of stuff.  

I got one of these used for $60 https://wiki.seeedstudio.com/DSO_Quad/

It's 72MS/s and it's awesome.  There is third party opens source firmware for it.  With the open source firmware it can even be hooked to serial lines and display the data on the lines.  

I was originally going to get one of those cheaper little DSOs but discovered this one and just happens across one online.  It was used but still in the original box.   I've been real happy with it for what I do.   

On Sun, May 17, 2020, 10:00 <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?

 

 

James Lynes
 

I like GQRX as well. It has a TCP/IP interface that lets you modify settings via another program(I use Perl).

I have several frequency scanner programs set up. One has a table of frequencies for the Sun N Fun airshow.

James

Gigabyte
 

The speed of most of those little scopes is not fast enough for a lot of stuff.  

I got one of these used for $60 https://wiki.seeedstudio.com/DSO_Quad/

It's 72MS/s and it's awesome.  There is third party opens source firmware for it.  With the open source firmware it can even be hooked to serial lines and display the data on the lines.  

I was originally going to get one of those cheaper little DSOs but discovered this one and just happens across one online.  It was used but still in the original box.   I've been real happy with it for what I do.   

On Sun, May 17, 2020, 10:00 <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?

 

 

Bill Cromwell
 

Hi,

A tale of my first purchase of a used scope. In my early 20s I saw an ad in the paper (remember those?) for used trade school scope, very reasonably priced. I made arrangements to goto fellow's house around sunrise the next day. He was waiting for me in his kitchen while the rest of his family slept. We plugged the scope in and turned it on. He looked dismayed and insisted had worked only a half hour earlier.

I removed the covers and I found a bad connection. I borrowed his soldering iron and repaired it. I reassembled it and then...
I bought it -shrug- I used it for several years.

Don't give up any possibilities.

73,

Bill KU8H

On 5/17/20 12:35 PM, Robert D. Bowers wrote:
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?
--
bark less - wag more

Robert D. Bowers
 

You'll encounter all sorts at hamfests, and find some really decent people there (as well as monsters).  My good scope (needed for my research) - the guy sold it to me for a price I could afford, but with extracting a promise I wouldn't try to turn around and sell it for a profit - that I was going to use it!  (Ditto for my BitX20 which I plan to convert to 10 meters.)  I've lucked out on a few other items - and look forward to hamfests starting up again (I've got a bunch of 'junque' I want to trade off - clear out storage a bit and have some fun!)

I'd add to your comments:

For someone seeking 'start-out' test equipment, see if you can find a local experienced ham in your area who'd be willing to go with you (maybe even a group - it's been known to happen).  Someone who is really knowledgeable and experienced can often spot the ugly-as-h*ll-but-a-real-deal items, and know what to avoid.  As you wrote, you might even find someone who enjoys helping out 'newbies' and would be willing to give someone equipment (I've been known to do that - and I've known hams who did).  Indeed, one of the people on this server gave me a BitX40!  (It's a prized piece, set up for portable/emergency comm use - doubly so as it reminds me of a kindness I experienced). 

The more people work together and help each other out, the more fun it can be!

Bob

On 5/17/20 12:54 PM, Randy.AB9GO wrote:
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@....



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