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Re: Step attenuator for QRP transmitter to TinySA

 

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?TRY? ? ? ? ? ? ??
Amazon.com: step attenuator rf
www.amazon.com


?Walt Cates, WD0GOF
?

A majority of acceptance is not proof of correctness.



From: [email protected] <[email protected]> on behalf of bigusmith via groups.io <bigusmith@...>
Sent: Thursday, February 11, 2021 8:43 PM
To: [email protected] <[email protected]>
Subject: Re: [tinysa] Step attenuator for QRP transmitter to TinySA
?
Dang!? That doesn't bode well for the utility of the Kay attenuator.? I am not used to dealing with RF output power in Decibels instead of watts, but from what little I have gleaned from discussions on-line, 10 Db attenuation wouldn't be enough to bring 1 watt of RF down to the level that would be comfortable for the TinySA.

I need to find a table which shows RF output in say, 1/2 watt steps from 1/2 watt to 5 watts, and at each step, how many Db of attenuation is needed to bring to RF down to the proper input level to feed into the TinySA.? I would pay $5 0r $10 in a heartbeat for such a chart, as I don't want to fry my TinySA and have to drop another fifty bucks for a replacement.

It would also be nice to know the proper input power to the TinySA...in watts, volts (DC, RMS, & PtoP), and Db's since I have run into attenuators which all use different units of measurements and I don't know how to compare them...it's the old apples and oranges gambit!

Somewhere, I read that the Kay 520 had 1- 60 Db attenuation (i guess that would be? 0,1, 2, 3, 6, 10, 20, 30, 40, 50, 60 DB or something of that ilk) but they didn't say what the max watts would be.

FleaBag (eBay) has a number of in-line 10 pole switched attenuators for sale at reasonable prices, but they all seem to be for very low power use with max input power of 0.25 0r 0.50 watts which wouldn't be useful for my 1 to 5 watt transmitters.? They say they are for Ham Radio use, but I don't know where they will find a big enough market among the QRPp milliwatters to have dozens of vendors selling 0.25 Watt attenuators.

I'm just rambling on now out of pure frustration.

EuGene, KA5NLY

Re: Step attenuator for QRP transmitter to TinySA

 

Dang!? That doesn't bode well for the utility of the Kay attenuator.? I am not used to dealing with RF output power in Decibels instead of watts, but from what little I have gleaned from discussions on-line, 10 Db attenuation wouldn't be enough to bring 1 watt of RF down to the level that would be comfortable for the TinySA.

I need to find a table which shows RF output in say, 1/2 watt steps from 1/2 watt to 5 watts, and at each step, how many Db of attenuation is needed to bring to RF down to the proper input level to feed into the TinySA.? I would pay $5 0r $10 in a heartbeat for such a chart, as I don't want to fry my TinySA and have to drop another fifty bucks for a replacement.

It would also be nice to know the proper input power to the TinySA...in watts, volts (DC, RMS, & PtoP), and Db's since I have run into attenuators which all use different units of measurements and I don't know how to compare them...it's the old apples and oranges gambit!

Somewhere, I read that the Kay 520 had 1- 60 Db attenuation (i guess that would be? 0,1, 2, 3, 6, 10, 20, 30, 40, 50, 60 DB or something of that ilk) but they didn't say what the max watts would be.

FleaBag (eBay) has a number of in-line 10 pole switched attenuators for sale at reasonable prices, but they all seem to be for very low power use with max input power of 0.25 0r 0.50 watts which wouldn't be useful for my 1 to 5 watt transmitters.? They say they are for Ham Radio use, but I don't know where they will find a big enough market among the QRPp milliwatters to have dozens of vendors selling 0.25 Watt attenuators.

I'm just rambling on now out of pure frustration.

EuGene, KA5NLY
Re: Starting this month, we have printed power warning labels on the surface of tinySA.

 

Spec sheet says the Kay 520 is rated for half a watt.? If it were my attenuator, I wouldn't push my luck.
Re: Step attenuator for QRP transmitter to TinySA

 

¿ªÔÆÌåÓý

I have a similar rotary attenuator that's rated for 2 watts.? I'd use that as an upper limit.? The Kay model is zero to ten dB.

73 charlie, k1xx

On 2/11/2021 5:17 PM, bigusmith via groups.io wrote:

I have a Kay Model 520 (Kay #80138) 0 - 10 scale rotary attenuator that I would like to use to allow me to test 100 Milliwatt to 5 Watt QRP transmitters using my TinySA, but I have not been able to find a spec sheet on the attenuator, so I don't know how many watts input it can handle and how much attenuation it will provide.

I, of course, do not want to overload the attenuator and/or the TinySA if I try to test my 5 watt QRP rig.? Anyone have any ideas?

EuGene, KA5NLY

Step attenuator for QRP transmitter to TinySA

 

I have a Kay Model 520 (Kay #80138) 0 - 10 scale rotary attenuator that I would like to use to allow me to test 100 Milliwatt to 5 Watt QRP transmitters using my TinySA, but I have not been able to find a spec sheet on the attenuator, so I don't know how many watts input it can handle and how much attenuation it will provide.

I, of course, do not want to overload the attenuator and/or the TinySA if I try to test my 5 watt QRP rig.? Anyone have any ideas?

EuGene, KA5NLY
Re: Starting this month, we have printed power warning labels on the surface of tinySA.

 

Eugene,
I would not put more than 100mw into that Kay. It is a 10 db step attenuator 0-70db. Why get separate attenuators for each transmitter? Just use one transmitter under test at a time. Get a 30db 10 watt attenuator. That makes a watt to milliwatt converter. So then your various transmitters are converted to -3, 0, 3 and 7 dbm. These are all safe levels for the tinysa. If you want, you could add your Kay 520 on the output of the 30db attenuator to reduce by about 10-20 db more.
Gary
W9TD
Re: serial USB not recognized - a clone ? - "to be, or not to be, that is the question"

 

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Thanks Martin, mine works OK and is exactly as you say. The other chap seemed concerned that it was not in the Ports list when in DFU mode.

On 11/02/2021 09:34, Martin J.K. wrote:

Geoff,

you wrote ''As soon as I enter DFU mode via config, the device disappears from the Ports list''.
That is how it is supposed to be with the TinySA in DFU mode.

Now, in Device Manager, section Universial Serial Bus controllers
you should see ''STM Device in DFU Mode''.

Martin 9A2JK
Re: serial USB not recognized - a clone ? - "to be, or not to be, that is the question"

 

Geoff,

you wrote ''As soon as I enter DFU mode via config, the device disappears from the Ports list''.
That is how it is supposed to be with the TinySA in DFU mode.

Now, in Device Manager, section Universial Serial Bus controllers
you should see ''STM Device in DFU Mode''.

Martin 9A2JK
Re: Starting this month, we have printed power warning labels on the surface of tinySA.

 

On Wed, Feb 10, 2021 at 11:17 PM, Carsten Bormann wrote:
I don¡¯t recollect immediately if a lower input than 10dBm gives you better results with the tinySA.
When measuring harmonics of a transmitter you want maximum spur free dynamic range of the tinySA.
This spur free dynamic range depends on the input level at the mixer. With +10dBm input the mixer will see at least -20dbm which is not optimal
For best measurement results try to get the input level to the tinySA between -25dBm and -15dBm so you can still use the built in attenuator to optimize the measurement
?
--
------------------------------------------
For more info on the tinySA go to https://tinysa.org/wiki/
Re: Starting this month, we have printed power warning labels on the surface of tinySA.

 

EuGene,
You can check the attenuation steps of the Kay 520 by turning on the tinySA calibration signal and connecting your atttenuator to HIGH and LOW on the tinySA.? I think it is 0dB to 70dB in 10dB steps.? It should be good for at least 0.5 watts, and probably works reasonably well to at least 500MHz.? (I have seen one reference to it working up to 2GHz.)
--John Gord


On Wed, Feb 10, 2021 at 10:53 PM, bigusmith wrote:
Carsten,

I'm looking to get attenuators to use with various QRP transmitters baur am not sure how much dB of attenuation is needed to use for each of the QRP transmitters with the following watts output:? 0.5 watts, 1 watt. 3 watts, & 5 watts.? ?I will select four 10 watt max input attenuators, one for each of those four transmitters, and have the following attenuations to choose from: 6dB, 10dB, 20dB, 30dB, 40dB.? I will label each one with which transmitter if will be used to provide a safe input to the Tiny SA.

I do have a KAY Elemetrics model 520 step attenuator but have been unable to fins a spec sheet on it to let me know it max input in watts and the min & max attenuation steps in dBs, so I'm hesitant to use it for anything while I am in the dark on it specs.

EuGene, KA5NLY
Re: Starting this month, we have printed power warning labels on the surface of tinySA.

 

Hi EuGene,

I don¡¯t know why you are specifically addressing me, but here goes:

5 W is 37 dBm (log10(5 W / 1 mW) log10(5000) ¡Ö 3.7).
Since you don¡¯t really know what exactly the transmitter will output, let¡¯s say you want to be safe up to 40 dBm, giving 3 dB safety margin.
10dBm is the max safe input, and 40 dBm - 10 dBm = 30 dB (no m;
dB is a measure of gain or attenuation; dBm is a measure of power by giving the gain relative to 1 mW).
Of course, the fact that an attenuator nominally is 30 dB does not mean that it really is at the frequency you are going to use it with, so that may use up some of the 3 dB safety margin we gave ourselves above.

Now, you probably don¡¯t just want to not blow up the tinySA, but also get a good measurement. I don¡¯t recollect immediately if a lower input than 10dBm gives you better results with the tinySA.

Gr¨¹?e, Carsten

On 2021-02-11, at 05:58, bigusmith via groups.io <bigusmith@...> wrote:

Carsten,

I'm looking to get attenuators to use with various QRP transmitters baur am not sure how much dB of attenuation is needed to use for each of the QRP transmitters with the following watts output: 0.5 watts, 1 watt. 3 watts, & 5 watts. I will select four 10 watt max input attenuators, one for each of those four transmitters, and have the following attenuations to choose from: 6dB, 10dB, 20dB, 30dB, 40dB. I will label each one with which transmitter if will be used to provide a safe input to the Tiny SA.

I do have a KAY Elemetrics model 520 step attenuator but have been unable to fins a spec sheet on it to let me know it max input in watts and the min & max attenuation steps in dBs, so I'm hesitant to use it for anything while I am in the dark on it specs.

EuGene, KA5NLY
Re: Starting this month, we have printed power warning labels on the surface of tinySA.

 

Carsten,

I'm looking to get attenuators to use with various QRP transmitters baur am not sure how much dB of attenuation is needed to use for each of the QRP transmitters with the following watts output:? 0.5 watts, 1 watt. 3 watts, & 5 watts.? ?I will select four 10 watt max input attenuators, one for each of those four transmitters, and have the following attenuations to choose from: 6dB, 10dB, 20dB, 30dB, 40dB.? I will label each one with which transmitter if will be used to provide a safe input to the Tiny SA.

I do have a KAY Elemetrics model 520 step attenuator but have been unable to fins a spec sheet on it to let me know it max input in watts and the min & max attenuation steps in dBs, so I'm hesitant to use it for anything while I am in the dark on it specs.

EuGene, KA5NLY
Level steps with attenuation dialed in #tinysa

 

Hello Eric,

I noticed an issue when using the tinySA in 'Low Output' mode:
The new "level steps" (-10dB -1dB set +1dB +10dB) in the latest firmware works great until a value is put into the 'External Amp' field. I was using 41 dB of external attenuation and had -41 dialed into this field.I then tried to change the output level by selecting the -10dB step and the SA ignored the external amp value and reverted to what would be displayed with no external value dialed in.

73,
--
John AE5X
Re: serial USB not recognized - a clone ? - "to be, or not to be, that is the question"

 

What vendor ID/product ID pair do you see?

Gr¨¹?e, Carsten
Re: serial USB not recognized - a clone ? - "to be, or not to be, that is the question"

 

¿ªÔÆÌåÓý

When I connect the tinySA to the USB port, it appears in device manager on the Ports(COM & LPT) as "USB serial device ( COM6)".

As soon as I enter DFU mode via config, the device disappears from the Ports list. On the tinySA app it appears on the upload firmware as Port_#0003.hub_#0004 followed by a string of code. Upload works OK. It also works on STMicroelectronics? Dfuse Demo. Again, no indication on the device manager but it works.

On 10/02/2021 18:42, Wolfgang OE1MWW wrote:

On Wed, Feb 10, 2021 at 09:26 AM, Gyula Molnar wrote:
/g/tinysa/message/3040
interresting link, thanks for that. But all this can and will not help in my setup, because
my tinySA (clone) is not shown as a com port device with a missing driver. Therefore
DfuSeDemo? does not recognize my tinySA clone in DFU mode. The STM32 Boot-
loader does not help.

The only indication I see is in Windows Device Manager on 'USB Controller' as an
'Unknown Device' (see picture). My default com ports showing no changes or new
entries if I plug in/power on the tinySA clone. Deinstalling the 'Unknown Device'
will bring it up after the next off/on cycle.

USBVIEW.exe (Microsoft) and USBDeview.exe (Nirsoft) showing all kind of connected,
or even disconnected devices, but never ever any info/change by the tinySA clone.
I guess, since the one message (see my previous post) says 'Error 29' Windows does
not know what type of? USB device has been connected - audio, keyboard, com port,
or whatever. Looks like a garbled USB interface routine in the firmware.

At the end, it's a lesson learned about crippled USB devices ;-)

73's de OE1MWW
Wolfgang

Re: Metal case for TinySA

 

I have had both my NanoVNA and my TinySA in the metal case for about a year. The cases has cut the RF noise by about 90%.
I attached a photo of them.
I also use a cut down pice of plastic phone screen protector over the displays.
Clyde Lambert KC7BJE?

20210203_181557.jpg

Re: serial USB not recognized - a clone ? - "to be, or not to be, that is the question"

 

On Wed, Feb 10, 2021 at 09:26 AM, Gyula Molnar wrote:
/g/tinysa/message/3040
interresting link, thanks for that. But all this can and will not help in my setup, because
my tinySA (clone) is not shown as a com port device with a missing driver. Therefore
DfuSeDemo? does not recognize my tinySA clone in DFU mode. The STM32 Boot-
loader does not help.

The only indication I see is in Windows Device Manager on 'USB Controller' as an
'Unknown Device' (see picture). My default com ports showing no changes or new
entries if I plug in/power on the tinySA clone. Deinstalling the 'Unknown Device'
will bring it up after the next off/on cycle.

USBVIEW.exe (Microsoft) and USBDeview.exe (Nirsoft) showing all kind of connected,
or even disconnected devices, but never ever any info/change by the tinySA clone.
I guess, since the one message (see my previous post) says 'Error 29' Windows does
not know what type of? USB device has been connected - audio, keyboard, com port,
or whatever. Looks like a garbled USB interface routine in the firmware.

At the end, it's a lesson learned about crippled USB devices ;-)

73's de OE1MWW
Wolfgang

Re: serial USB not recognized - a clone ? - "to be, or not to be, that is the question"

 

/g/tinysa/message/3040
--
73, Gyula HA3HZ
Re: TinySA driver???

 

I had the same issue. I let Windows 10 searching for the driver but it did not find one. Then I googled for 'STM32 Bootloader' and download the driver from?.

Now Windows was able to update and after putting the TinySA in DFU mode?DfuSeDemo sees it as 'STM Device in DFU Mode' . Thereafter I was able to download the latest firmware.

Regards, Rudi
Re: serial USB not recognized - a clone ? - "to be, or not to be, that is the question"

 

Gentlemen,

thanks for all your tips. Whatever port I plug in, or cable I am using, the tinySA never
shows up in com ports, just in the section of the 'USB Controller' section as an 'unknown device'

Right click and remove / deinstall and power cycling the tinySA results in the same info.

Windows 10/x64 Laptop:
Info: Unknown USB device (error requesting a device description)
in properties: This device stopped because it caused errors. (Code 43) An error occurred while solving the USB device descriptor.

Windows 7 Pro/x64
Info: Unknown device
in properties: This device does not work properly because the device firmware does not provide the necessary resources. (Code 29)

Windows 7Pro/x64
Today this PC did not even recognized the connected device, different cables, different ports, plug-in/plug-out cycling
Have no idea why.

Remark: I am using Windows 7 pro and Windows 10 in German language, the shown messages had been translated.

So, it looks like, the USB section in this clone has a fault and does not report it's device type to Windows.

FYI: I am a developer for Ham Radio software, 'CW via CAT' etc. , so I am pretty firm with all this com port stuff.

Never mind, a hopefully 'real tinySA' was ordered at Aliexpress Zeenko Store yesterday.
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