[Boatanchors] "Sweep" techniques

[J. Forster]

I just Googled:

"sweep alignment" "IF strips" and got a bunch of useful hits.

-John

============



> Basically, it's pretty straight forward. An IF stage is little but a band
> pass filter with gain.
>
> You put in a constant amplitude, unmodulated, swept RF signal and observe
> the amplituse of what comes out.
>
> Suppose you are doing a 10.7 MHz IF.
>
> You could do it manually with an RF generator:
>
> 1. Check your generator's output flatness by looking at the RF output on a
> 'scope or with a simple diode detector. It should be flat over the range
> of interest, typically 10.6 to 10.8 MHz, for an IF BW of 200KHz.
>
> 2. Hook the IF amp up between the generator and then plot the measured
> output v. frequency, point by point.  This is slow and a PITA, but it
> shows you whatr you what to do.
>
> 3. Now change the RF generator for a sweep Gen. The RF outpot goes to the
> IF as befor; the IF output to the 'scope or detector as before. Now hook
> the "Sweep Out" of the SG to the 'scope horizontal input in X-Y mode.
>
> The 'scope should now display frequency on the X-axis; Output Amplitude on
> the Y-axis. This display is what you need to align IFs.
>
> If you are going to align a full receiver, first align the IF; then retune
> the SG to the receive frequency and align the RF section.
>
> FWIW,
>
> -John
>
> ==================
>
>
>
>
>>
>>
>>
>> Hello to all. I've been a ham for a long time and there is one area
>> where
>> not only is my knowledge severely lacking, but I seem to be unable to
>> find
>> any decent info on this technique.
>>
>> The subject is 'sweep alignment' of IFs and filters, etc.
>> I have quite a few Tek 'scopes, and also a nice collection of MODERN
>> Sweep/Function Generators. Krohn-Hite, Exact, etc. I have also purchased
>> and repaired a ton of test equipment including 'scopes and TDRs, in
>> addition to my boatanchor collection.
>> The manuals for the Sweepers assume you know how to connect them and use
>> them.
>>
>> A while back, I noticed that there were several articles in ER Magazine
>> showing the swept response of various boatanchors, (SX-117, etc).
>> Unfortunately, the authors never describe the test methodology. I have
>> purchased more than a few (!!) "How to use your Sweep/Signal Generator"
>> books.
>> However, they are pretty old and only deal with old, tube type TVs.
>> I even suggested to Ray at ER Mag that this subject would make a great
>> article and he agreed, but I still haven't seen anything.
>>
>> So, could some of you guys with all the expertise in this area (Carl,
>> Al)
>> at least give me a shove in the right direction?
>>
>> Yes, I have searched the WWW extensively and no joy......
>>
>> Thank you!
>>
>> ron
>> N4UE
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>
>
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