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Yes (as I¡¯ve repeatedly said here already?
eg check the photos on sellers pages?
on other designs check for a direction arrow?
sometimes you must read the spec (shock horror) or assume the male end is the high power input end?
ps ive bought several of these and they are good when used correctly. ?(Check the detail photos ) ?
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I would not trust an attenuator manufacturer that does not mark which is the i/p.
73
Jeff
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Bruce Akhurst Sent: 19 June 2024 09:28 To: [email protected]Subject: Re: [tinysa] Attenuators Yes eg check the photos here on other designs check for a direction arrow sometimes you must read the spec or assume the male end is the high ps ive bought several of these and they are good when used correctly. (Check the detail photos ) input end
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Jeff?
Yes it¡¯s often a case of you only know if you know..
Unless marked differently the male plug = input rule seems safe yet little publicity for this has seeped through to amateur experimenters it seems ? ??
Putting an attenuator chain together it¡¯s easy to forget and get the input one reversed (I often red paint or tape the inputs to help my ¡®late night head¡¯ remember)?
It doesn¡¯t help that professionally we paid high prices for reversible ones just for safety (and a slightly better spec ?) but that puts another zero on the cost prices ?
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I must admit that I am not entirely convinced that some of the attenuators that have i/p and o/p shown on the pictures are actually uni-directional, particularly the low power ones. I suspect that it has just become some sort of convention to have to show i/p and o/p in the pictures.
I find it hard to believe that any manufacturer (even Chinese) would fail to indicate the i/p end if there was a danger of destroying the item.
73
Jeff G8HUL
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Bruce Akhurst Sent: 19 June 2024 09:57 To: [email protected]Subject: Re: [tinysa] Attenuators Jeff Yes it¡¯s often a case of you only know if you know.. Unless marked differently the male plug = input rule seems safe yet little publicity for this has seeped through to amateur experimenters it seems Putting an attenuator chain together it¡¯s easy to forget and get the input one reversed (I often red paint or tape the inputs to help my ¡®late night head¡¯ remember) It doesn¡¯t help that professionally we paid high prices for reversible ones just for safety (and a slightly better spec ?) but that puts another zero on the cost prices
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I already mentioned that below 0.5W it¡¯s unlikely to matter even if marked directionally?
I think we can assume the photos and info come from the factories. ?Two input ends both meeting power, swr and attenuation spec will have a noticeable cost impact so skipping it is understandable?
Many larger attenuators actually have a large arrow on the side (which also cost something to provide)?
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The high price stuff specifically describes bi-directional attenuation even on low ish power?
see description section
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I think if it from China, I would question its power handling, I have an old Philco 30Db rated 50 watts, and handles that all day long with some slight warming.
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So far, all the cheap SMA attenuators I have are symetrical with the shunts equal. Size dictates so rather low wattage resistors though.
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Not sure what you¡¯re saying or how you know this ??
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Take them apart, most 2w and below have a symmetrical T or PI inside. It is cheaper to make the part symmetrically using the same value components on the input and output? than having to inventory, store and pick different parts.
John
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Bruce, "how do we know?"? Some of us on this group and the NanoVNA group have done this professionally for decades.? Sure, I'm? completely against tooting my own horn, but I've been using both professionally for at least 3 to 4 decades. ? In retirement, we're here to share what we've learned both through formal education and experience with others.? That's what these groups are about.
But having written that, one bit of advice:? For the most part, AVOID YOUTOOB done by others than professionals!?
Dave - W?LEV
Not sure what you¡¯re saying or how you know this ??
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Dave
?
I'm not a newbie by a long way and as I stated earlier was first using professional spectrum analysers in VHF UHF comms design, manufacture and field repairs in the 1970's.? Doesn't mean I know everything but? . .??
I have not taken any SMA attenuators to bits and based on previously taking BNC style ones to bits I wasn't sure I could evaluate the power handling of the input and output resistors on sight even if I did.? ?If you have then thankyou for sharing your insights and can you therefore tell me why many /most sellers of these cheap 2W SMA (and BNC) attenuators go to great lengths to specify the input and outputs (consistently as Male = input.)
?
As I said previously I've much experience with expensive Bird HP etc attenuators and terminators and their attenuators will indeed (mostly) be described and ordered (at a price) as bi directional (with unidirectional available on some items)? and this is what we did for the reasons I said already.? ? ?
Personally I'm very happy if the 10x cheaper ones from China exist and can be 10x cheaper by being uni-directional above a watt or so or any other non problematic reason.? No doubt this 'flaw' is a relief to Bird /HP as well?
?
No, I am not a You tube Fan - I think your comment is verging on rude but maybe its just mis-aimed - I Learnt and used my Electronic, RF and Comms engineering skills and qualifications the old way; at Work? and college.? (And How do we know / Is this still true/ are we sure? was never a question you'd get your ear clipped for..)
?
Anyway , clearly I've offended you so I'll leave this thread in your capable hands
?
?
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Bruce, I did not mean to be rude.? I usually use the term "newbie" but worded it as I did to avoid rudeness.? I've just viewed so many.,....many YouToob presentations which are just blatantly wrong and? against all basic electronics and physics principles.? And the uninitiated believe them and snake oil becomes conventional knowledge.? I generally no longer view any Youtoob unless it's done by professionals.? At times I become so frustrated with the snake oil and witchcraft that I err on the knee jerk side of a reaction.? Yes, it's rude, but I have no idea of the background of emailers.? Sorry I might have offended anyone, but please understand my background as well.? I generally assume the poster has a very basic understanding of electronics and a bit of physics.
These groups exist to help others who have legitimate and good questions.?? But I can't go back to the rank basics of electronic theory.? After all, passing the ham license is supposed to instill that basic understanding of electronics, antennas, and feedlines.? I won't take that comment further as it's one of my hot buttons with the "memorize and forget" philosophy.??
I had a real honest Ohm's Law question on my Novice exam in 1959 way back when we had to show calculations.? And a real honest Smith Chart problem on my Advanced and Extra exams - in front of FCC - in roughly 1974.
BTW:? Of some 30++ potential engineers I interviewed while working at HP in Northern Colorado, none, yes, NONE, of them could put the DC case of Ohm's Law on the white board!!!? I had one, yes, ONE, technician candidate who could put Ohm's Law on the white board, but struggled a bit to use it.? He eventually made it work.? Needless to write, we hired?him with no further questions asked.
Dave - W?LEV
Dave
?
I'm not a newbie by a long way and as I stated earlier was first using professional spectrum analysers in VHF UHF comms design, manufacture and field repairs in the 1970's.? Doesn't mean I know everything but? . .??
I have not taken any SMA attenuators to bits and based on previously taking BNC style ones to bits I wasn't sure I could evaluate the power handling of the input and output resistors on sight even if I did.? ?If you have then thankyou for sharing your insights and can you therefore tell me why many /most sellers of these cheap 2W SMA (and BNC) attenuators go to great lengths to specify the input and outputs (consistently as Male = input.)
?
As I said previously I've much experience with expensive Bird HP etc attenuators and terminators and their attenuators will indeed (mostly) be described and ordered (at a price) as bi directional (with unidirectional available on some items)? and this is what we did for the reasons I said already.? ? ?
Personally I'm very happy if the 10x cheaper ones from China exist and can be 10x cheaper by being uni-directional above a watt or so or any other non problematic reason.? No doubt this 'flaw' is a relief to Bird /HP as well?
?
No, I am not a You tube Fan - I think your comment is verging on rude but maybe its just mis-aimed - I Learnt and used my Electronic, RF and Comms engineering skills and qualifications the old way; at Work? and college.? (And How do we know / Is this still true/ are we sure? was never a question you'd get your ear clipped for..)
?
Anyway , clearly I've offended you so I'll leave this thread in your capable hands
?
?
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Uh .. which Dave? There are many....' DaveD KC0WJN
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ==============================
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On Jun 20, 2024, at 17:55, Bruce Akhurst via groups.io <bruce@...> wrote:
? Dave
?
I'm not a newbie by a long way and as I stated earlier was first using professional spectrum analysers in VHF UHF comms design, manufacture and field repairs in the 1970's.? Doesn't mean I know everything but? . .??
I have not taken any SMA attenuators to bits and based on previously taking BNC style ones to bits I wasn't sure I could evaluate the power handling of the input and output resistors on sight even if I did.? ?If you have then thankyou for sharing your insights and can you therefore tell me why many /most sellers of these cheap 2W SMA (and BNC) attenuators go to great lengths to specify the input and outputs (consistently as Male = input.)
?
As I said previously I've much experience with expensive Bird HP etc attenuators and terminators and their attenuators will indeed (mostly) be described and ordered (at a price) as bi directional (with unidirectional available on some items)? and this is what we did for the reasons I said already.? ? ?
Personally I'm very happy if the 10x cheaper ones from China exist and can be 10x cheaper by being uni-directional above a watt or so or any other non problematic reason.? No doubt this 'flaw' is a relief to Bird /HP as well?
?
No, I am not a You tube Fan - I think your comment is verging on rude but maybe its just mis-aimed - I Learnt and used my Electronic, RF and Comms engineering skills and qualifications the old way; at Work? and college.? (And How do we know / Is this still true/ are we sure? was never a question you'd get your ear clipped for..)
?
Anyway , clearly I've offended you so I'll leave this thread in your capable hands
?
?
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Dave D., I assumed Bruces's comments were aimed at me.? Yes, too many Daves.
Dave E. - W?LEV
Uh .. which Dave? There are many....' DaveD KC0WJN
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ============================== ? Dave
?
I'm not a newbie by a long way and as I stated earlier was first using professional spectrum analysers in VHF UHF comms design, manufacture and field repairs in the 1970's.? Doesn't mean I know everything but? . .??
I have not taken any SMA attenuators to bits and based on previously taking BNC style ones to bits I wasn't sure I could evaluate the power handling of the input and output resistors on sight even if I did.? ?If you have then thankyou for sharing your insights and can you therefore tell me why many /most sellers of these cheap 2W SMA (and BNC) attenuators go to great lengths to specify the input and outputs (consistently as Male = input.)
?
As I said previously I've much experience with expensive Bird HP etc attenuators and terminators and their attenuators will indeed (mostly) be described and ordered (at a price) as bi directional (with unidirectional available on some items)? and this is what we did for the reasons I said already.? ? ?
Personally I'm very happy if the 10x cheaper ones from China exist and can be 10x cheaper by being uni-directional above a watt or so or any other non problematic reason.? No doubt this 'flaw' is a relief to Bird /HP as well?
?
No, I am not a You tube Fan - I think your comment is verging on rude but maybe its just mis-aimed - I Learnt and used my Electronic, RF and Comms engineering skills and qualifications the old way; at Work? and college.? (And How do we know / Is this still true/ are we sure? was never a question you'd get your ear clipped for..)
?
Anyway , clearly I've offended you so I'll leave this thread in your capable hands
?
?
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Yes, per Dr. Seuss... DaveD KC0WJN
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ==============================
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On Jun 20, 2024, at 18:59, W0LEV via groups.io <davearea51a@...> wrote:
? Dave D., I assumed Bruces's comments were aimed at me.? Yes, too many Daves.
Dave E. - W?LEV
Uh .. which Dave? There are many....' DaveD KC0WJN
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ============================== ? Dave
?
I'm not a newbie by a long way and as I stated earlier was first using professional spectrum analysers in VHF UHF comms design, manufacture and field repairs in the 1970's.? Doesn't mean I know everything but? . .??
I have not taken any SMA attenuators to bits and based on previously taking BNC style ones to bits I wasn't sure I could evaluate the power handling of the input and output resistors on sight even if I did.? ?If you have then thankyou for sharing your insights and can you therefore tell me why many /most sellers of these cheap 2W SMA (and BNC) attenuators go to great lengths to specify the input and outputs (consistently as Male = input.)
?
As I said previously I've much experience with expensive Bird HP etc attenuators and terminators and their attenuators will indeed (mostly) be described and ordered (at a price) as bi directional (with unidirectional available on some items)? and this is what we did for the reasons I said already.? ? ?
Personally I'm very happy if the 10x cheaper ones from China exist and can be 10x cheaper by being uni-directional above a watt or so or any other non problematic reason.? No doubt this 'flaw' is a relief to Bird /HP as well?
?
No, I am not a You tube Fan - I think your comment is verging on rude but maybe its just mis-aimed - I Learnt and used my Electronic, RF and Comms engineering skills and qualifications the old way; at Work? and college.? (And How do we know / Is this still true/ are we sure? was never a question you'd get your ear clipped for..)
?
Anyway , clearly I've offended you so I'll leave this thread in your capable hands
?
?
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Thanks Dave,
Hopefully we'll keep that in mind, I know I will
and I AM OLD.
Mike C. Sand Mtn GA
On 6/20/2024 2:17 PM, W0LEV wrote:
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Bruce,
"how do we know?"? Some of us on this group and the NanoVNA
group have done this professionally for decades.? Sure, I'm?
completely against tooting my own horn, but I've been using
both professionally for at least 3 to 4 decades. ? In
retirement, we're here to share what we've learned both
through formal education and experience with others.? That's
what these groups are about.
But
having written that, one bit of advice:? For the most part,
AVOID YOUTOOB done by others than professionals!?
Dave
- W?LEV
Not
sure what you¡¯re saying or how you know this ??
--
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Hello, just joined the group as I'm about to order the TinySA Ultra. I'm new to RF and to me the subject of the input attenuators for the TinySA is of paramount importance.
I'm going to experiment with the basic RF receiver circuits and in the beginning I want to explore some basic mixers, filters, oscillators, etc. For these low power experiments am I going to be fine with the previously mentioned here 2W attenuators from AliExpress?
Will it be enough to connect a 30 dB attenuator to the TinySA input to be well below the input safety margin for my tasks?
Being new to RF I can't tell what simple circuits like for instance a typical Superhet mixer will feed into the TinySA input.
I would appreciate some education on the subject.
Should I maybe buy a simple power meter along to know what I'm going to feed into the SA input?
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?hi no name? ;)
there's 2 long threads in the group about input attenuators Have a search if you havent already
The avg. power meter wont measure the maximum low power levels for the TinySA You will need a decent power meter capable of measuring very low power levels .... milliWatts
cheers Dave VK2TDN
----- Original Message -----
To: <[email protected]>
Cc:
Sent: Thu, 04 Jul 2024 15:43:18 -0700
Subject: Re: [tinysa] Attenuators
Hello, just joined the group as I'm about to order the TinySA Ultra. I'm new to RF and to me the subject of the input attenuators for the TinySA is of paramount importance.
I'm going to experiment with the basic RF receiver circuits and in the beginning I want to explore some basic mixers, filters, oscillators, etc. For these low power experiments am I going to be fine with the previously mentioned here 2W attenuators from AliExpress?
Will it be enough to connect a 30 dB attenuator to the TinySA input to be well below the input safety margin for my tasks?
Being new to RF I can't tell what simple circuits like for instance a typical Superhet mixer will feed into the TinySA input.
I would appreciate some education on the subject.
Should I maybe buy a simple power meter along to know what I'm going to feed into the SA input?
Email sent using Optus Webmail
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Get /create yourself a table ?with 1 dBm steps and power and voltage (at 50ohms) columns?
Start writing all the examples you can find on it to get used to the respective power levels and also input capabilities
Counting down the row difference between the source and your input capability tells you how many dB attenuation you need
Checking the power column difference tells you the minimum attenuator power handling you need?
?
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Bruce Akhurst
John Cunliffe W7ZQ
Mike C.
Dave