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Re: Attenuators
Much easier to calculate that way! "Sniffing the air" I put 10db between the antenna and sa (typical urban radio environment) The LNA works magic at that level. Connecting a radio directly to the sa (1-5 watts) I have 80db total attenuation between them. Very clean readings!
I do not use the unit's internal attenuator because you cannot use both internal attenuation and the LNA at the same time.? |
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Re: Attenuators
Bruce Hawkins
Mini circuits isn't random amazon or eBay bought attenuators.?? In my past employment, engineers were blowing up attentiors and input to spectrum analyzers etc.? This is my experience. While I hear your points. I should have anticipated possible criticisms... I still stand. I don't recommend applying the unit under test (a transmitters), output power, to attenuators rated for the same power level. Regardless to the manufacturer of the attenuators. Although, professional brands, will more likely tolerate that better. Best regards, Bruce Hawkins - AC6DN.? Sent from my Android phone.? And from: ac6dn@... On Jun 15, 2024 3:46 AM, G8HUL <g8hul@...> wrote:
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Re: Attenuators
I get the most use out of 10, 20 and 30 dB attenuators. Zack W9SZ On Sat, Jun 15, 2024, 9:05 AM Richard B. Emerson via <pavilion=[email protected]> wrote: On Sat, Jun 15, 2024 at 01:12 AM, Bob Ecclestone wrote: |
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Re: Attenuators
On Sat, Jun 15, 2024 at 01:12 AM, Bob Ecclestone wrote:
Why the obsession with 3dB attenuators in these discussions, I do not know!The interest comes from using a 3 db attenuator as at least a hedge against ESD problems. Otherwise, yeah, not something the world of SA rises or falls on. :) 73 Rick KC3DOO |
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Re: Attenuators
On Sat, Jun 15, 2024 at 09:39 AM, G8HUL wrote:
So a 100W 3db attenuator can only have 100W CW applied to it, NOT 200W.Modern attenuators and dry loads, unlike much older designs using carbon composition or similar, tend to use chip resistors, which will not withstand an overload, even for a few mS. Regards, Martin |
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Re: Attenuators
How the power rating is specified varies across application areas and manufacturers with some specifying dissipation and some total input power; reading the specification is rather key.
All that aside, if you have the space is almost always wise to over-specify and under-run devices such as this with the headroom being useful and keeping temperatures down where possible. |
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Re: Attenuators
Attenuators are generally rated at the max power that you can apply to them NOT how much power they can dissipate.
(at a specified ambient temp, with a de-rating at higher temps). So a 100W 3db attenuator can only have 100W CW applied to it, NOT 200W. Peak pulse power and short term rating are different matters. 73 Jeff G8HUL |
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Re: Attenuators
To me, if an attenuator cannot dissipate the rated load constantly then that is not it¡¯s rated power.
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Re: Attenuators
That is certainly not the way most manufacturers, including Mini Circuits, specify their attenuators. A 100W attenuator will be spec'd at 100W CW max input power , usually at 25 degrees C with a de-rating as the temp goes up. There will also be a peak pulse rating, with sometimes a de-rating curve for power with time.
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73 Jeff G8HUL -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of W0LEV Sent: 14 June 2024 22:12 To: [email protected] Cc: Wiggle Pig <wigglepig@...> Subject: Re: [tinysa] Attenuators This has been pointed out previously by another ham. If one starts with 100-watts from the transmitter in CW, RTTY, or the digital modes, what is dissipated in a 3 dB attenuator? NOT the full 100-watts. The 3-dB attenuator "eats" 50-watts and PASSES along 50-watts at its output. Therefore, it dissipates 50-watts. If properly spec'ed, that should be for "key down" conditions for a very long time. Another 3 dB attenuator would "eat" 25-watts and pass along 25-watts. It should dissipate 25-watts for a very long time. Take the statement from the previous post: (QUOTE): If the radios output is 100w. Then absolute minimum wattage is 100 Watts. This statement is just not true. If you needed to dissipate ALL of your 100-watt power, that would require a dummy load, and NOT an attenuator. And, then, yes, it would need to be a 100-watt DUMMY LOAD with NOTHING out the "other end" as there is no "other end" with a dummy load. Dave - W?LEV On Fri, Jun 14, 2024 at 6:05?PM Bruce Hawkins via groups.io <> <ac6dn@... <mailto:[email protected]> > wrote: I suggest the opposite... If the radios output is 100w. Then absolute minimum wattage is 100 Watts. That's ok if you don't transmit longer than few seconds. Otherwise I'd choose, at least, twice the expected output (200w). 3x is the better, if the transmission time is many minutes. Another thing. The rated power of 100w, 3db load, bought on ebay or Amazon, is likely not 100w - But 100w for one or two seconds, before it blows. Best regards, Bruce Hawkins - AC6DN. Sent from my Android phone. And from: ac6dn@... <mailto:ac6dn@...> On Jun 14, 2024 3:39 AM, Wiggle Pig <wigglepig@... <mailto:wigglepig@...> > wrote: It should be rated to handle the *dissipation* in that unit. So if you put 10 W total into a 3 dB attenuator then it needs to be rated for 5 W dissipation. -- Dave - W?LEV |
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Re: Attenuators
For many measurements TX side, build yourself an 60, 80 or even a 100+dB RF tap (Contact me diredctly for build instructions) as I think they are way outside the scope of this channel. They can also be built from junk box parts or by buying a couple of very cheap components.
I am sure that 99% of your measurements will fall well within those perameters. Paul |
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Re: Attenuators
¿ªÔÆÌåÓýHi Dave,Your comments are absolutely correct for 3dB attenuators. Why the obsession with 3dB attenuators in these discussions, I do not know! Why would you use a 3 dB attenuator for measurements on a 100W Tx, unless that is all you have:-). You need at least 60dB as a minimum for the TinySA/Ultra at 100W, (gives -10dB out), 80dB is better to ensure spur free measurement. But a 10dB 100W attenuator has to dissipate 90W. And a 20dB 100W attenuator has to dissipate 99W. Pretty close to 100W in my book. Anything higher than 20dB and it has to dissipate the full 100W [+/- 1% ;-)]. So I would buy a 20dB (1W out) or 30dB (100mW out) 100W attenuator followed by the ubiquitous 2W Ebay attenuators or your surplus HP, R&S, etc switched attenuator if you prefer. And don't forget, a 100W attenuator will get hot with 100W carrier (CW or digi modes). Just my 2 cents worth... 73...Bob VK2ZRE On 15/06/2024 7:12 am, W0LEV wrote:
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Re: Attenuators
On Sat, Jun 15, 2024 at 02:10 AM, Mike C. wrote:
Hi Mike, Lucky you, but in essense it seems that you are saying the same as me. The TinySA and NanoVNA are tremendous pieces of equipment (even more so for the price point). No way would they compare on how exactly they measure up to that piece of equipment, but for the price there is absolutely zero comparrison. For 90% of what I want, they are more than adequate for the basic/average/above average user eg 99% of Hams. An SA or VNA in this price point is unheard of and has to be absolutely applauded. You cannot buy DEAD equipment on Ebay for less than 5x the price. Paul |
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Re: firmware erasure?
Erik and others were right - you cannot brick the TinySA. I deleted cube 2.16 and replaced it with 2.15. I should have exercised some quality control time before rushing to program. As originally and clearly recommended in the wiki. I programmed it successfully with 2.15. It lives and breathes again. Thank you all for the thoughtful assistance and feedback. Valis StartMail makes private and encrypted email easy. ! On Friday, June 14, 2024 5:47 PM, m0cnl <m1cxz.m0cnl@...> wrote:
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Re: Attenuators
¿ªÔÆÌåÓýHi Paul, Just a little tongue in cheek, but I happen to have a couple of Agilent N9342N (aka: HP dc to daylight spec anal) that track in the ballpark of $12k and weigh a 'ton'. Certainly can't put them in your shirt pocket but Erick's little 'tweaky-treasure' gets my vote every time. Just sayin'? :0) Mike C. Sand Mtn GA On 6/14/2024 6:37 PM, m0cnl wrote:
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Re: Thoughts for a firmware update
The only time that I have had a problem updating the firmware was on a cloned device. Even then, following the advive from the wiki and shorting the two pins at power-on and starting again worked for me.
The reason that I IMMEDIATELY wanted to update the firmware to a known official version was that it was the only way that I could verify a real from clone TinySA. I didn't cry when the update went wrong. I worked through the problem, re-read something from the wiki that I missed and proved that my device was a fake/clone. IMHO: the very idea of setting up this group was for people to ask questions and USERS to answer them. Thereby leaving the developer/s to concentrate on actual issues. Bitching about people asking a question in the very place that I am sure that you have asked questions in the past is really not community or HAM radio spirited at all. Paul |
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Re: firmware erasure?
Not sure why nobody has mentioned the lines from the wiki that say:
NOTE WHERE IT SAYS: Luckily it is impossible to brick the tinySA |
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Re: Attenuators
I actually bought a set of 1,2,3,6,10,20,30,40dB attenuators, advertised as 2W? DC-8G from aliexpress (So cheap that I thought that if they are junk then I will just file 13 them). I tested them on my NanoVNA-H4 and was surprised to find that all of them tested to be within 0.02 and 0.1dB below the stated value. They also measured to have a VSWR below 1.2:1 all the way up past 2GHz, I didn't bother testing higher in frequency as I don't need anything higher than 1.5GHz at the very highest. I won't be even thinking about putting more than 1-100mW through them. I will be using quality high power attenuators before them and only using them to fine tune attenuation levels that I need. Or using something like a 60dB RF tap just to sniff off a very small signal where those attenuators will become useful.
I fully expect to have many people argue with my logic for buying them and how I intend to use them, but in my opinion, if you keep your wits about you then there shouldn't be a problem as long as you test them properly first and don't expect them to handle anything like the power they say. Like I said, I'm only ever going to put 5% MAX of the stated power through them, which I cannot see as a problem. The TinySA and NanoVNA are (with no dissrespect) budget test equipment. Most people using them will start with budget accessories. If they need to upgrade to better equipmet at higher costs then they will do as their needs require. Just my ?0.02p Paul |
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Re: Attenuators
This has been pointed out previously by another ham.? If one starts with 100-watts from the transmitter in CW, RTTY, or the digital modes, what is dissipated in a 3 dB attenuator?? NOT the full 100-watts.? The 3-dB attenuator "eats" 50-watts and PASSES along 50-watts at its output.? Therefore, it dissipates 50-watts.? If properly spec'ed, that should be for "key down" conditions for a very long time.? Another 3 dB attenuator would "eat" 25-watts and pass along 25-watts.? It should dissipate 25-watts for a very long time.? Take the statement from the previous post:? (QUOTE):?
If the radios output is 100w.? Then absolute minimum wattage is 100 Watts. This statement is just not true.? If you needed to dissipate ALL of your 100-watt power, that would require a dummy load, and NOT an attenuator.? And, then, yes, it would need to be a 100-watt DUMMY LOAD with NOTHING out the "other end" as there is no "other end" with a dummy load. Dave - W?LEV On Fri, Jun 14, 2024 at 6:05?PM Bruce Hawkins via <ac6dn=[email protected]> wrote:
-- Dave - W?LEV |
Richard B. Emerson
Mike C.