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 Post subject: Heathkit RF generator connectors
PostPosted: Jan Sat 11, 2020 11:56 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Germantown, IL USA 62245
Hello,
I acquired this Heathkit signal generator at a sale and it's marked as model IGW-19. It's very similar to the IG-102 except for 2 jacks on the front panel marked "Direct RF". What are these for?
Tom Ackerman


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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Sun 12, 2020 12:18 am 
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I suspect ahead of attenuation for a counter.


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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Sun 12, 2020 12:44 am 
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I did connect a counter to them but I seemed to be getting different readings than from the RF output connector. Maybe I wasn't set up right.
Tom


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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Sun 12, 2020 5:16 pm 
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Have you looked in the manual?

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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Sun 12, 2020 7:28 pm 
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That's where you go to when all else fails. I can't find any data on this particular model, IGW-19. I have a book on the IG 102, which is very similar but doesn't have these jacks. This has a label on the back indicating it was made in Canada, if that makes any difference.

Tom


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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Sun 12, 2020 8:08 pm 
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Counters are fussy when you aren't giving them a sine wave. Further, they have minimum input level requirements that need to be satisfied.

The best solution is to put an oscilloscope on the signal and see what it's about.


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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Tue 14, 2020 9:57 pm 
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Checked it on a scope and found an unmodulated signal much stronger than at the RF out connector. Looked inside and see the red connector goes to the tuning cap for the low bands and the black goes to the chassis. That explains why I got different frequencies from the RF out and the RF direct connectors. I still don't know what it's for. If a counter is connected to these jacks it changes the tuned circuit.

Tom


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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Wed 15, 2020 3:00 am 
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Well if the counter is shifting the frequency by loading at the test point, presumably it would be the same frequency at the other output when counter hooked there. Now maybe you could "modify" the test point with a resistor in series inside to swamp out any loading effects, or maybe perhaps a very tiny value capacitor coupling from the jack to the tuning cap. As long as there is enough signal to drive the counter. As the tuning cap is right in the oscillator circuit, perhaps the level is pretty high to start with and reducing it alot could still trigger the counter and get a reading while giving isolation. Plus the less signal that can get outside the case the better, as unless you have perfect shielding to the counter from the generator, RF could leak and affect tests where you only want a very small signal for testing.

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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Wed 15, 2020 2:20 pm 
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Might be interesting to just see if you can fit a little digital frequency meter into the same space taken up by the binding posts....

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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Thu 16, 2020 2:52 pm 
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I remembered this from reading Jeff Tranters book. Pg 84

The Heathkit IG-102 RF Signal Generator (Jeff Tranter's youtube)
https://www.youtube.com/watch?v=wtdJt13i7nA
He mentions it @ 1:19

Also in his book he mentions this

"The IG-102S was the Berkeley Physics Laboratory version which was identical except for additional set of jacks used for for high level "direct" output needed for experiments in the laboratory"

"...not suitable for radio and television servicing as high level RF radiates from the additional jacks.......one could remove or disconnect the jacks to revert it to an IG102"

"The IGW-19 was the factory assembled version of the IG-102S"

Radio Museum link to IG-102S
https://www.radiomuseum.org/r/heath_rf_ ... ig_10.html


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 Post subject: Re: Heathkit RF generator connectors
PostPosted: Jan Thu 16, 2020 4:32 pm 
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Location: Germantown, IL USA 62245
What I'm seeing is the RF Direct jacks serve no useful purpose for the average user. They're actually a detriment if you're using it to align radios, as they're a source of unwanted radiation. Thanks for the replies.

Tom


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