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HP 8656B signal generator cable

2FB327

2FB327

Active Member
Oct 31, 2012
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I finally found a brand new old stock 8656B, my question is I need a cable to go from the RF output to the radio.
The connector on the back of the unit looks like a 4240-062 N style connector, the manual calls for a 50 ohm type N male (us mil-c-39012).
Is there a premade cable that has this type of connector on the end and pl259 on the other?
8656b.jpg
 

Thanks, so I would want a N type female to a UHF male? For give me but the end in the photo would be a N style male I'm assuming.
 
I use a NMO to BNC converter plug on the front of the Hp, and then use a BNC to BNC cable. Then I use a BNC to PL-239 converter plug to go into the radio under test.

But having the Hp sig/gen is only half of the setup; the other half is how to gauge what is happening to the receiver. I use the SINAD program, an isolation xformer, and a laptop to dial in the receiver:

http://www.comtekk.us/sinad.htm

http://www.comtekk.us/isolators.htm

That'll git 'er done . . .
 
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What a nice piece, it came, with the original binder still wrapped in plastic. It has all the connection in the back, I ordered the n style male to so-239.
Turned it on an it did the self check and all works so far. I'm off work this week so I'll catch up on some reading.
I remember a few years back you were discussing the Sinad with someone.
Is Sinad the way to go? What are my other options? Spectrum Analyzer?
 
2FB327 said:
What a nice piece, it came, with the original binder still wrapped in plastic. It has all the connection in the back, I ordered the n style male to so-239.
Turned it on an it did the self check and all works so far. I'm off work this week so I'll catch up on some reading.
I remember a few years back you were discussing the Sinad with someone.
Is Sinad the way to go? What are my other options? Spectrum Analyzer?
Click to expand...
Apples and Oranges . . .

Spectrum analyzer is used primarily for output signals.
SINAD is for receive; it is the 'other half' of the equipment needed for receive alignments.
 
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So all I will need is the two comtekk parts and a laptop. Are there any other option or is this the most efficient?
 
Just remember that the HP 8656B is a generator. Meaning you cannot transmit into it.
She is a fine piece of test gear.

Since this is a generator you would need to obtain an external sinad meter to use in conjunction with the HP. I prefer a sinad meter over using a volt meter on AC scale. Reason is a sinad meter will filter the required 1KHz tone out so you are not tuning the receiver for noise but actual signal.

Spectrum analyzer are useful for looking at transmitted signal purity. You cannot do this with a scope. Scope is for your modulation purity.

Over time you will find that you will want to make up several different types of test leads. I would also order a N-male to BNC female. This way you can attached probes that have BNC on them. Many possibilities. Say you are working on a ham radio and you are not finding a signal like 63.xxx MHz from a local oscillator. Make you a cable to attach to the SG and couple the other end to the LO stage. You can now inject the signal into that stage to see if the radio comes back to life. If it does you now know something in that stage is faulty.
 
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Thanks for your help. I'm going thru the manual now, and then it's on to the Sinad articles Rob posted. It's stating to make sense. I'm going to concentrate my efforts on the receive side. I'm amazed at the difference in receive from one radio to another. Just following the factory manual with my 2040 I was able to get a couple of 29's to hear.
I would like to see some videos on the setup and use of Sinad.
 
My connector came and I'm ready to get going. I need some help that the thick binder an quick reference guide can't help me with, there are no diagrams of the front panel.

1. In the mod section there is a red light " Lo ext" what does this refer to?
I have been able to change the percentage and change from the internal 400Hz or the 1kHz tone.

2. In the first step it calls for 1Khz at 30% mod, ok I guess I just use the internal tone, but in later steps it calls to reduce the sg to 0.4uV and then to 1uV. How do I go about this?

Any help or photos of initial setup would be appreciated.
 

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