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Re: No pulse on CAL when freq sweeping on signal generator #tinysa #ultra


 

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Using a standard 10:1 CRO probe connected via a high voltage DC Block (min 200V) to the 50 ohm SA input will present Low C / Hi Z to the DUT and also gives about 60dB attenuation to the SA input. Handy around tube and FET circuits.
A DC Block is just a capacitor in series with the centre conductor of the adaptor. You can get them in SMA, BNC, N, etc.
Be careful to check the specs of the DC Block, a lot of those on Ebay, etc are only around 25-50V.
HTH...Bob VK2ZRE


On 19/05/2025 11:45 pm, Mike EI9FEB wrote:

As soon as I got my S/H HP141T SA years ago I made a noise source using a zener diode, high pass filter and MAR6 wide band amp on stripboard.

I've not tried it yet with IFTs and the TinySA basic, or my Rigol SA, but it has advantages over a tracking generator as it can be used at RF in of radio and connect IFT out to SA. Note some kinds of IFTs, especially on valve (tube) gear would be detuned and Q reduced by load of the SA. You need a remote FET buffer (I use J310 because I have them).

I had a wobbulator and the noise source plus SA was far superior. You can use a tracking generator if driving a filter direct, but again you may need a buffer (output to simulate normal driving device) or be misled.

Even changing the mixer or amp device with a different part may need the IFT to be retuned (i.e. swap 1L6 to a DK92), so unless it's SAW, ceramic or crystal IF (easy to have a passive match on input and output) tuning or examining an IFT directly with any test gear is fraught with pit-falls, especially other than a secondary to a bipolar transistor.


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