CB and Ham Radio Techs Love Their Bird Wattmeters

[joeqsmith]

I don't have a amplifier that works much above 100MHz.   The one I put together from a kit is setup for below this.     

I had roughly 40dB loss between the Signal Hound and the amplifier.  I set the generator to 150MHz and the level to 0dBm (plus 40 or 10Watts).  Using the same setup, the two cheap back to back ham adapters were inserted in place of the N adapter.   I measure a difference of 0.13dBm. 

9.705Watts vs 10W may be fighting words at BD139's CB pub. 

***
Attempting to run at 200MHz, where we expect to see a fair bit of error, the amplifier acts as an attenuator.

[joeqsmith]

The home made kit amp doesn't have a spreader and the sink is too small to run it near what the FET is rated for.

Here is the N vs the cheap ham adapters with the same setup but 50MHz 100W.  The two are now within 0.01dBm.  Pretty much what we would expect unless the cheap connectors are really cheap.   

[bd139]

9.705Watts vs 10W may be fighting words at BD139's CB pub. 

5% is fine 

Actually found this. The power meter was the last one I built. One Caddock MP850 50 ohm 1% resistor, a 1N4148, a pot and random panel meter I paid £1 from a hamfest



Calibrated with a DC power supply 

Note the suspicious lack of SO-239's 

[xrunner]

I think ham cables and connectors are fine to use.   

Dropping the crappy BNC adapter and using the two cheap ham to N adapters back to back with an old Amphenol adapter.   To get the same number of connection points, I used 3 X N adapters.  Used the Lite to measure S21 of the two configurations.

I found the sweeps I did in 2019 on a USB transfer drive. I can't recall exactly what I put in series but it was "ham" adapters - about 6 of them. I calibrated my SpecAn and tracking generator and then inserted the string of adapters. As you can see the loss isn't all that bad. The worst band is 70 cm which gets you at most 0.5 dB of attenuation (for about 6 adapters in series).

[joeqsmith]

For higher power, I placed another 10dB attenuator in the chain that can handle the power.  Set the level to 53dBm (200W) with the N adapter then swapped in my cheap ham adapters.  We loose about 2W.  Odd.    Attached a thermocouple to the Amphenol adapter sitting between the two.   Again, these are very low end adapters and it's not really fair to judge the connector base on these.  But it is amusing considering the only people purchasing them are going to be the Bird owners. 

https://www.amazon.com/Coaxial-Adapter-Connector-Female-Straight/dp/B074RFJK1S/ref=sr_1_18?crid=2MUME3VWU6CZT&keywords=uhf+adapter+kit&qid=1656969366&sprefix=UHF++adapter%2Caps%2C75&sr=8-18

[joeqsmith]

I like the old key.  You watch these people who learn more than one speaking language and the hams can't learn 26 letters and a few numbers.      Too busy learning how to connect their PCs to their radios I guess.   

[xrunner]

For higher power, I placed another 10dB attenuator in the chain that can handle the power.  Set the level to 53dBm (200W) with the N adapter then swapped in my cheap ham adapters.  We loose about 2W.  Odd.    Attached a thermocouple to the Amphenol adapter sitting between the two.   Again, these are very low end adapters and it's not really fair to judge the connector base on these.  But it is amusing considering the only people purchasing them are going to be the Bird owners. 

https://www.amazon.com/Coaxial-Adapter-Connector-Female-Straight/dp/B074RFJK1S/ref=sr_1_18?crid=2MUME3VWU6CZT&keywords=uhf+adapter+kit&qid=1656969366&sprefix=UHF++adapter%2Caps%2C75&sr=8-18

Whew yea those are really cheap parts Joe.   

When I showed my friend my sweeps he said they probably don't apply to many hams around here. I said why not? Because you don't have dirty rusty beat-up parts like other hams.

I said yea you are probably right! 

Gathering the parts for assembly ...

[joeqsmith]

With the amp off and after eating, the meter still reads high.   A bit of thermal mass there with all that copper.

[joeqsmith]

Not to leave the CBers out in the cold, dropped down to 30MHz.   The attenuator is rated for 300W convection cooled.  I don't trust it.     With fan cooling set it for 54dBm or around 250W.  Added a thermocouple to the sink.  Gets a bit warm but not too bad.  I shut it down at 51C.  More interesting it the connectors are up to 32C.     I understand hams don't believe in torque wrenches and to be fair, these have no way to torque them.  They are however very tight and still appear to have a bit of loss. 

[xrunner]

Did you make that amp? If not what is it a commercial unit?

[joeqsmith]

The small one was from a kit I put together to hop up an old Tektronix current probe I have.   You can see it here:
https://www.eevblog.com/forum/projects/home-made-pa-and-load/

Adding 0.77dBm or roughly another 50Watts.   Stuffed a couple of other fans on it.   I don't dare push the attenuator any harder.   Of course, the connectors get a bit warmer.   

[vk6zgo]

I think ham cables and connectors are fine to use.   

Dropping the crappy BNC adapter and using the two cheap ham to N adapters back to back with an old Amphenol adapter.   To get the same number of connection points, I used 3 X N adapters.  Used the Lite to measure S21 of the two configurations.

I found the sweeps I did in 2019 on a USB transfer drive. I can't recall exactly what I put in series but it was "ham" adapters - about 6 of them. I calibrated my SpecAn and tracking generator and then inserted the string of adapters. As you can see the loss isn't all that bad. The worst band is 70 cm which gets you at most 0.5 dB of attenuation (for about 6 adapters in series).

In the mean, cold, hard, world where RF Techs eke out their miserable existences, the worst case there is a negligible difference.

[joeqsmith]

About 1:25 in, you can see one of my childhood keys.   I started out with one of those cheap gold keys from Radio Shack.   I had stripped the paint and eventually repainted it gray, to match the Bird meter that I never bought.     

[vk6zgo]

I like the old key.  You watch these people who learn more than one speaking language and the hams can't learn 26 letters and a few numbers.      Too busy learning how to connect their PCs to their radios I guess.   

Joe, I was too busy having a life & earning a living----ham radio was always wedged in somewhere there, in whatever time was left over.
Studying electronics is a nice, quiet, activity (apart from all the swearing), Morse is full of annoying noises, so is even further down the food chain than the other ham activities.

[vk6zgo]

Not to leave the CBers out in the cold, dropped down to 30MHz.   The attenuator is rated for 300W convection cooled.  I don't trust it.     With fan cooling set it for 54dBm or around 250W.  Added a thermocouple to the sink.  Gets a bit warm but not too bad.  I shut it down at 51C.  More interesting it the connectors are up to 32C.     I understand hams don't believe in torque wrenches and to be fair, these have no way to torque them.

(Neither do "N" connectors)

They are however very tight and still appear to have a bit of loss.

32C is not a lot over room temp.(though, maybe your Lab is freezing cold?)
Hams very seldom go "key down" for any length of time, so in practice, they would be unlikely to reach that temperature.

I would normally go for a default of a length of coax with "N" one end, & PL259 the other, as I can never find the bloody adaptors when I need them!

[joeqsmith]

Joe, I was too busy having a life & earning a living----

Last I checked, I was still with the living and continue to earn a living.   

I understand hams don't believe in torque wrenches and to be fair, these have no way to torque them.

(Neither do "N" connectors)

The typical mid grade Ns I've shown in this thread do and believe it or not, you can actually buy a torque wrench for them.
https://www.centricrf.com/torque-wrenches/n/

[vk6zgo]

Joe, I was too busy having a life & earning a living----

Last I checked, I was still with the living and continue to earn a living.   

I understand hams don't believe in torque wrenches and to be fair, these have no way to torque them.

(Neither do "N" connectors)

The typical mid grade Ns I've shown in this thread do and believe it or not, you can actually buy a torque wrench for them.
https://www.centricrf.com/torque-wrenches/n/

The flats on the normal everyday "N" connectors  like the ones you show, are used to hold the body of the thing, while the clamp thread at the cable end is tightened.
The coupling, which screws onto the female connector is designed to be hand tightened.

Yes, Virginia, there are "N" connectors with the coupling having a hexagon shape, (I have a couple), but they are far from being "mainstream", one major drawback being that they are fairly large, so  there is often insufficient clearance between adjacent connectors to use them.)

Oddly enough, Wiki quote not only a torgue setting for the hex ones, but for the hand ones, too.
Without a calibrated hand, or a "torque pipe wrench", I am at a loss to say why!

By the way, the coupling on a PL259, which is removable, will happily screw onto a female "N" connector.

[bd139]

Calibration for hand tightening is probably a misunderstanding. You should only use a torque wrench on N's in theory. Absolutely no one owns one though 

[vk6zgo]

Calibration for hand tightening is probably a misunderstanding. You should only use a torque wrench on N's in theory. Absolutely no one owns one though 

As I pointed out, normal "N" connectors which I have seen in many years in Radio & TV Broadcast work, have no provision for the use of a torque wrench.
 
Everybody else I have ever seen use them hand tightens them.
The hex type definitely could be torqued, but I'm afraid that my detector goes off the clock about this.

The main, quite legitimate, reason for torque wrenches with SMAs is to prevent damage to their delicate threads & internals, but "N" connectors are positively "agricultural" in comparison!

[joeqsmith]

As I pointed out, normal "N" connectors which I have seen in many years in Radio & TV Broadcast work, have no provision for the use of a torque wrench.
 
Everybody else I have ever seen use them hand tightens them.
The hex type definitely could be torqued, but I'm afraid that my detector goes off the clock about this.

The main, quite legitimate, reason for torque wrenches with SMAs is to prevent damage to their delicate threads & internals, but "N" connectors are positively "agricultural" in comparison!

As I stated, typical hams do not believe in torque wrenches.   Rather they place their faith in their Birds.   Your responses are typical of a ham.   While you like to use your call sign to communicate,   with your last comment about your having a life and earning a living, I suspect you also fall into another common trend I find typical with hams.  A while back I mentioned about hams who feel the need to write me outside of public forums for help and their reason for doing so.   Another side note about them is they while they value their time, they find everyone else's worthless. 
 
Debating torquing connectors and Bird Watt meters with a ham is really a waste of time.    A person wrote me once about how there was no need to measure anything beyond 400Hz.   I assume they were an electrician (writing skills higher than a child).  In their world, this is all they know (using that term loosely) and the concept of working with anything faster was black magic to them.   Explaining to someone at that level about human speech, radio and high speed digital designs is pointless.  They lack the education.   

The flats on the normal everyday "N" connectors  like the ones you show, are used to hold the body of the thing, while the clamp thread at the cable end is tightened.

Everyday "N" connectors are much like everyday transistors, op-amps .....    The flat is used to prevent the center from rotating while the hex nut is torqued.

Radio & TV Broadcast work, have no provision for the use of a torque wrench.   Everybody else I have ever seen use them hand tightens them.

When your limit yourself to hams and people working with low speed signals I wouldn't expect you to be exposed to it.   Much like a preschooler is not exposed to calculus. 

[joeqsmith]

They are however very tight and still appear to have a bit of loss.

32C is not a lot over room temp.(though, maybe your Lab is freezing cold?)

No need to guess as the first set of photos showed the ambient temperature.  After seeing the loss at higher power levels, I was curious if we would see some effects from resistive heating.   This of course led me to make the comment about them being tight.   

I wonder if the majority of the heating comes from losses inside the adapter or from a poor connection to the cable.   With the plastic insulation and all that copper thermal mass, I would imagine that the if we could section everything and take the measurements inside we would find them to be much hotter.   

[vk6zgo]

As I pointed out, normal "N" connectors which I have seen in many years in Radio & TV Broadcast work, have no provision for the use of a torque wrench.
 
Everybody else I have ever seen use them hand tightens them.
The hex type definitely could be torqued, but I'm afraid that my detector goes off the clock about this.

The main, quite legitimate, reason for torque wrenches with SMAs is to prevent damage to their delicate threads & internals, but "N" connectors are positively "agricultural" in comparison!

As I stated, typical hams do not believe in torque wrenches.   Rather they place their faith in their Birds.   Your responses are typical of a ham.   While you like to use your call sign to communicate,

 My responses are typical of someone who has spent most of their working life using the very connectors you are referring to.
The reason I use VK6ZGO as my "nickname" is pure laziness.
I was using it on QRZ.com, who, except in special circumstances, want people to identify in that way.
When I signed up here, it seemed a waste of time to have to remember another alias.
Some forums don't like ham calls, hence on the "UK Vintage Radio Repair and Restoration Discussion" Forum, I am "Oldmadham".

with your last comment about your having a life and earning a living, I suspect you also fall into another common trend I find typical with hams.

My point was that I found it a lot easier using time to learn Technical stuff, which I could do whilst still in the same room as my family, than spend time on Morse practice, which is really best done away from others.
I do not know your background, but I assume you had a formal University education, whereas in my case, I had to learn as I went, as progress through the technical ranks in my long term employer was through competitive examinations, with most of the material requiring much home study.
This necessarily, took precedence over ham radio.
After all, the reward  for passing the Morse test was being able to use HF, whereas that of the technical study was a better job!

 

A while back I mentioned about hams who feel the need to write me outside of public forums for help and their reason for doing so.   Another side note about them is they while they value their time, they find everyone else's worthless.
 

I would not do that sort of thing--questions on a forum are fair enough, but chasing people over & above that is, except in special circumstances, harassment!

Debating torquing connectors and Bird Watt meters with a ham is really a waste of time.    A person wrote me once about how there was no need to measure anything beyond 400Hz.   I assume they were an electrician (writing skills higher than a child).  In their world, this is all they know (using that term loosely) and the concept of working with anything faster was black magic to them.   Explaining to someone at that level about human speech, radio and high speed digital designs is pointless.  They lack the education.   

The flats on the normal everyday "N" connectors  like the ones you show, are used to hold the body of the thing, while the clamp thread at the cable end is tightened.

Everyday "N" connectors are much like everyday transistors, op-amps .....    The flat is used to prevent the center from rotating while the hex nut is torqued.

The vast majority of "N" connectors in Commercial use do not have a "hex nut".
Techs & EEs working in those areas have the necessary skills to hold the body & tighten the knurled round threaded coupler.---by hand!
In any case, out in the real world, "clamp" type "N" connectors like you are using are all but obsolete, replaced by crimp connectors which have no flats!

 

Radio & TV Broadcast work, have no provision for the use of a torque wrench.   Everybody else I have ever seen use them hand tightens them.

When your limit yourself to hams and people working with low speed signals I wouldn't expect you to be exposed to it.   Much like a preschooler is not exposed to calculus.

Ignoring your sneer, TV & Broadcast work includes frequencies up to UHF for the actual station transmitters, as well as links operating at microwave frequencies.
The OB links I set up at a later employer used a length of Coax with "N" connectors both ends to connect between the RX or Tx & the horn feeding the dish.
I would have thought coax would have been a bit marginal at the two frequencies we used (7 & 13 GHz), but apparently not, although the coax was just over 1m long.
We tightened the "N" connectors by hand!

[joeqsmith]

Ignoring your sneer, ....

It's there for your entertainment, much like this entire thread.   

[bd139]

Calibration for hand tightening is probably a misunderstanding. You should only use a torque wrench on N's in theory. Absolutely no one owns one though 

As I pointed out, normal "N" connectors which I have seen in many years in Radio & TV Broadcast work, have no provision for the use of a torque wrench.
 
Everybody else I have ever seen use them hand tightens them.
The hex type definitely could be torqued, but I'm afraid that my detector goes off the clock about this.

The main, quite legitimate, reason for torque wrenches with SMAs is to prevent damage to their delicate threads & internals, but "N" connectors are positively "agricultural" in comparison!

I did microwave avionics stuff for military. We definitely used torque wrenches.

Well I tell a lie, we had them but they only got used on anything we'd get fired for not using them with.

Hams don't use them because they cost money. Broadcast doesn't use them because they cost time. Military uses them because they may cost lives.

[joeqsmith]

I did microwave avionics stuff for military. We definitely used torque wrenches.

Well I tell a lie, we had them but they only got used on anything we'd get fired for not using them with.

I watched a 60 Minutes episode (or some such show) back in the 80's  that I believe was the catalyst for this:
https://www.congress.gov/bill/101st-congress/senate-bill/20/text

Of course I could be totally wrong but from what I remember large company was supplying electronics to the DOD.  They could not get the mil grade parts and substituted.  When the mil grade parts would arrive, they kept the baby papers for their records and them moved the parts into long term storage, preserving the evidence.   One of the workers realized just how fucked up this was and goes public.  Things didn't go well for the employee. 

https://www.behnwyetzner.com/whistleblower-compensation-awards/northrop-government-contractor-fraud/