Hi Arv
A tracking generator can be made with say 1x 10dB and 2x 20dB pads with a variable 0-10dB control? which gives a 60dB range. I have used TG¡¯s for a very long time, if I wanted to go to very low levels ( which is pretty rare ) I would prefer to add some external pads to get down to very low levels. But most of the time sweeping amplifiers, filters and mixers you are around 0 to -40 dBm.
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The TC is normally made by allowing a little compression in the LO drive to the mixer so that the level changes (that are almost inevitable in sweeping? ) ?are lost in the slight limiting action. A DBM works nicely when the LO port is driven quite hard.? But you can attenuate the RF port drive by either using a pot? directly between the LO and the DBM or by using a tuned amplifier and varying the gain. If you wanted to be real smart then rectify the tuned amp output and compare that against a voltage from a pot in an integrator that drives the buffer amp.
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I do feel that you might get fed up swapping links around and they are difficult to screen which may cause stray signals from local broadcasters to creep in and cause confusion.? There are some cheap and tiny DPDT relays that cost very little, might be inclined to make a? PCB with pads switched by relays on the basis that if one messes you around it gets dumped and another cheap clone takes it¡¯s place.? Then you can have a 6 way switch to control the relays? with 0-10-20-30-40-50 dB clicks .
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This is a variation on the ¡°Law of Sod¡¯s¡± , if you have a spare or two it will never get used ( unless you loose the spares!!!!!). But if you don¡¯t have a spare then you will need it at a critical moment.
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If you have a 0-50dB module? with 1206 surface mount R¡¯s on the solder side of a DS PCB then you should be OK up to around 100MHz with the normal ?50 ohm tracks of 2.7mm on 1/16¡± board.? Make a few and you should be all set.
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( I would use a diode across every relay coil and decouple the coil connections with -say 100nF to board ground to stop leakage)
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Regards,
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Alan
G8LCO
Sent from for Windows 10
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