[R-390] R390 Dave N3DT, ask and then what is the input Z of the IF?

[dog]

Yes, my gen is only calibrated into 50Ω. I really wasn't aware that the 
IF input was hi Z, I really didn't look at it, but it makes sense given 
the filters are around 2K as I remember. There is a difference if I 
terminate the sig gen or not, but it's not a huge difference, certainly 
not 3dB as I remember. I understand where Roger is going with this 
though, it makes a lot of sense, but one can come at a baseline that can 
be used in a particular shop for reference for the IF modules. It's 
probably not worth the effort to try measuring the input of the IF, I 
may try the RF input one of these days.

I never did understand the diff in EMF and uV, it sort of escapes me 
because I've always worked in dBm where I've worked. Then there's EMF 
p-p too isn't there? I sort of remember that somewhere.

Thanks all,

Dave N3DT

On 3/15/2019 14:07, Jacques Fortin wrote:
> Roger, when you write: I suggest 150 uv into the IF deck at 455 and set the DC gain for - 7 volts on the DC load.
> Would you mean 150µV EMF (Electro Motive Force) or 150µV if the signal generator is terminated in 50 ohms ?
> This is because there is a 6 dB difference between the two....
> And I believe it was the intent of the question from Dave, N3DT.
>
> Many RF generators are calibrated regarding their output amplitude only if they are terminated in a 50 ohms load.
> In that context, if the output amplitude is adjusted to 150µV and left open-circuited (or connected to a very high impedance) 300µV will appear at the output, as being the voltage of the internal equivalent source of the generator, right ?
> And this is what we call 300µV EMF...
> In the case of the R390-A IF module, because the input impedance is very high, are we talking about 150µV EMF or 300µV EMF needed ??
>
>
> 73, Jacques, VE2JFE
>
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