Isidro,

I am using a pre made unit I bought 2018 or 19. It has a SBL-1 mixer terminated with 3db attenuators, a few band pass filters a limiting circuit and a couple of MMICs. It works well enough without having to go thorough any hoops. It would be simple? for people to build them self or if they don't want to do that spend the 50-60 bucks and buy it. There are ample of sellers on e-bay and Ali express. Of course, since there are at least as many clones out there as there are sellers the results may vary.

John

Hello Isidro,
What you say about using the normal IF port as input is true for the
minicircuits mixers such as the SBL1. But there are many other mixers
that can work right down to DC. Especially many of the IC mixers.
73 Ken g8beq

On 21/12/2022 19:50, Isidro Berniol wrote:

Hi,

This Description misses some important things.

Thie mixer IF port is used as input. If you select the right mixer the input can be DC coupled, allowing measurement down to very low frequencies.

Also it can make sense to use a higher IF then 10MHz for easy filter implementation.

To have a good level translation use a 3dB attenuator on all thee ports.

Mini Circuits high level mixers work great for this purpose.

All the Best,

Isidro

herunterladen

Am 21. Dez. 2022, um 16:14, "Kenneth Greenough via " < talktalk.net@groups.io target=_blank>g8beqglossop= @groups.io> schrieb:

Hello Larry,
An up converter is basically a mixer,double balanced being best for the
purpose and an oscillator.? For stability the oscillator will likely be
a crystal controlled one.? Say the osc' is on 10 MHz and fed into one
port of the mixer, low frequency signals you wish to monitor are fed
into the signal input of the mixer. The output of the mixer is the
10 MHz osc, very reduced due to the cancellation balance of the
mixer and the low frequency signals appear as modulation [ both
sidebands] of the 10 MHz. If you feed the output to the SA you can
monitor the modulation. in other words you have up converted the
low frequency signals.?? A down converter works in exactly the same
way to monitor higher frequencies which are above the upper limit of the SA.
?Ken g8beq?

On 21/12/2022 14:14, Lawrance A. Schneider wrote:

If ignorance were bliss, I'd be in heaven. ?I'm not there yet but I am ignorant.

What is an 'up converter'? ?Yes, I understand the words but that does not tell me what it is nor how it works.

Thanks, ? ? ? ? ? larry

Hi,

This Description misses some important things.

Thie mixer IF port is used as input. If you select the right mixer the input can be DC coupled, allowing measurement down to very low frequencies.

Also it can make sense to use a higher IF then 10MHz for easy filter implementation.

To have a good level translation use a 3dB attenuator on all thee ports.

Mini Circuits high level mixers work great for this purpose.

All the Best,

Isidro

herunterladen

Am 21. Dez. 2022, um 16:14, "Kenneth Greenough via " <talktalk.net@groups.io target=_blank>[email protected]> schrieb:

Hello Larry,
An up converter is basically a mixer,double balanced being best for the
purpose and an oscillator.? For stability the oscillator will likely be
a crystal controlled one.? Say the osc' is on 10 MHz and fed into one
port of the mixer, low frequency signals you wish to monitor are fed
into the signal input of the mixer. The output of the mixer is the
10 MHz osc, very reduced due to the cancellation balance of the
mixer and the low frequency signals appear as modulation [ both
sidebands] of the 10 MHz. If you feed the output to the SA you can
monitor the modulation. in other words you have up converted the
low frequency signals.?? A down converter works in exactly the same
way to monitor higher frequencies which are above the upper limit of the SA.
?Ken g8beq?

On 21/12/2022 14:14, Lawrance A. Schneider wrote:

If ignorance were bliss, I'd be in heaven. ?I'm not there yet but I am ignorant.

What is an 'up converter'? ?Yes, I understand the words but that does not tell me what it is nor how it works.

Thanks, ? ? ? ? ? larry

On Wed, Dec 21, 2022 at 11:13 AM, John Cunliffe W7ZQ wrote:

So a 0dbm signal in equals a 0dbm signal out and a -100 dbm signal in equals a -100dbm signal out. It tracks pretty good within +- 1-2db above 30khz.

First, thank you both (Kenneth Greenough &??John Cunliffe W7ZQ).

How are you sure the dbm is equivalent to dbm out? ?

larry

Thanks Kenneth,
Nice descriptions of the fundamental. This particular up converter uses an external 10Mhz oscillator that ideally should be synchronized to the spectrum analyzer for best accuracy.
It takes the low frequency input signal between about 10Khz and 2 Mhz and mixes it with the external source. It then applies some basic filtering and level adjustments and then outputs a signal above 10Mhz that mirrors the input signal in amplitude. So a 0dbm signal in equals a 0dbm signal out and a -100 dbm signal in equals a -100dbm signal out. It tracks pretty good within +- 1-2db above 30khz. Below that the sensitivity / dynamic range fails but is it still usable.
I use the 10Mhz cal output of the tinySA as the external oscillator. The signal as is, is too low so I added what I believed to be a 20db amplifier but it turns out is actually close to 30db on 10Mhz. That puts the 10Mhz signal right around 0dbm, perfect for the box and since it is derived from the internal clock of the tiny it is naturally synchronized to it.
Using the up converter I can now observe low frequency signals in the 50-150khz range (my interest) using the full dynamic range of the tinySA . The specs say it works up to 2Mhz but I have not tested it there.? Eric made a nice video about the performance of the tinySA on lower frequencies. This up converter gets around some of the performance issues.

John

Lawrence,

No it is the output directly from the box. The amplifier I am using is for the 10Mhz cal out signal from the tinySA that is at about -30dbm and thus to small for the input of the box. The box needs to have ~ 0 to +10dbm signal at the external 10Mhz clock input.With the external clock input at 0dbm my up converter directly tracks the input signal.

John

Hello Larry,
An up converter is basically a mixer,double balanced being best for the
purpose and an oscillator.? For stability the oscillator will likely be
a crystal controlled one.? Say the osc' is on 10 MHz and fed into one
port of the mixer, low frequency signals you wish to monitor are fed
into the signal input of the mixer. The output of the mixer is the
10 MHz osc, very reduced due to the cancellation balance of the
mixer and the low frequency signals appear as modulation [ both
sidebands] of the 10 MHz. If you feed the output to the SA you can
monitor the modulation. in other words you have up converted the
low frequency signals.?? A down converter works in exactly the same
way to monitor higher frequencies which are above the upper limit of the SA.
?Ken g8beq?

On 21/12/2022 14:14, Lawrance A. Schneider wrote:

If ignorance were bliss, I'd be in heaven. ?I'm not there yet but I am ignorant.

What is an 'up converter'? ?Yes, I understand the words but that does not tell me what it is nor how it works.

Thanks, ? ? ? ? ? larry