[Test-Equipment] HP 141 analyzer low gain

[Gary Schafer]

The output of the amp in the RF unit I think can be gotten to by 
removing the top cover of the RF unit and plugging it back in. Then 
remove to outer top cover plate on the 141. That should allow access to 
the top of the RF unit. The 50 mhz amp is at the top of the rear of the 
RF unit. The flexible cable goes to about the middle with a connector. 
The manual says to install a "T" connector there to make the level 
measurement.  That will tell me if everything is ok in the RF unit.

Now I need one of those small T connectors.  Anyone have one they want 
to sell? It is smaller than an SMA.

73
Gary  K4FMX


Arthur Shulman wrote:
> I had forgotten about the amp in the IF plugin, Gary. But it turned out not to be the
> culprit in my case.
> There must be a fair # of extender cables out there, but I've never been able to
> purchase them, except as a custom set, cost abt C$400. I would certainly be interested
> if an owner would RENT them out to needy individuals for, say, a month. With a deposit,
> of course, same as any rental. Then we could both get our gear fixed.
> I suppose I should approach my Cal Lab and see if they would be interested in selling
> obsolete cables! Ha!
> If you can easily measure the gain down thru the amp & mixer chain, let me know what
> you find. But do first try to find out in which plugin the problem lies.
> Arthur
> 
> Gary Schafer wrote:
> 
> 
>>Arthur Shulman wrote:
>>
>>>I had exacly the same problem with my 141T & 8445B, right down to the 20db loss
>>>of gain. It was not the mixer, but low gain in the 50Mhz amp that outputs to the
>>>IF section. My repair shop advised it was not worthwhile to continue the repair
>>>due to the labor involved in dissasembly, so I replaced the RF section with a
>>>known good unit. Has worked perfectly since, & I have the old module, still
>>>unrepaired by me.
>>>Suggest you try to borrow a different RF section, any range, and determine by
>>>substitution if the problem lies in the RF or IF plugin. Then you can decide what
>>>to do next. I think servicing this unit is almost impossible without the extender
>>>cables, & I highly recommend you consider that if you find the problem requires
>>>extensive dissasembly.
>>>I seem to recall that the amp with low gain was buried beneath a mass of other
>>>circuitry & hardware & was impossible to access for direct measurements. It was
>>>possible to measure gain loss around that block, however, & that's why I feel
>>>confident about the diagnosis, despite the fact that I was unable to determine
>>>the exact failed component.
>>>Please let me know what you discover, & good luck!
>>>
>>>Arthur Shulman VE3ZV
>>>
>>>
>>
>>Thanks for the tip. Another fella suggested the same thing, the 50 mhz
>>amp. There are two of them. One is on the output of the RF unit. Not
>>much too it and easy to get at. The next one is in the IF unit and looks
>>like it is buried.
>>
>>I will have to see if I can find a connector to check at the output of
>>the RF unit. It is smaller than an SMA, can't recall what type it is.
>>
>>Wish I had a set of cables!
>>
>>Thanks,
>>Gary  K4FMX
> 
> 
> 
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