[Premium-Rx] spectrum Analyzer to use as a signal monitor

[w3jn]

I've been viewing the current interest in panadapters with some interest.

You can easily convert 455 up to 10.7 MHz.  Build a small oscillator, 
variable from 11.14 to 11.16 MHz.  Feed the output of this oscillator into 
the LO port  a MiniCircuits double-balanced mixer.  THe input of the mixer 
should be attached to the 455 KHZ IF output of the receiver, the output will 
go to your 10.7 MHz panadapter.

A better, easier, and cheaper solution is to just find a 455 KHz panadapter. 
Heathkit made several models which are widely available on eBay.  IIRC you 
could build the panadapter for 455 KHz or whatever IF Heathkit used in their 
SOB-series radios.  Hallicrafters also made a 455 KHz panadapter in the 
40's.

Look at eBay closely over a month or so and I'm sure you'll find one of 
these panadapters, or an old commercial model (such as a WJ) that will fit 
the bill.  Or, you can find a receiver that already has a built-in 
panadapter (several WJ models or the MicroTel PR-700).

I've found that panadapters aren't really as useful as you might imagine. 
The spectrum width you see is limited by the bandwidth of the roofing 
filter, which is often <20 KHz.  More useful would be a 100 KHz range. 
Also, in many receivers, AVC action will prevent you from seeing a small 
signal next to the big signal that's centered in the passband of the final 
filter and detector.

If you already have a spectrum analyzer, I'd use it directly on an antenna 
rather than trying to use it as a panadapter.  The receiver just hampers the 
utility of the spectrum analyzer.  A panadpter that only sees 20 KHz is 
pretty worthless.

73 John

----- Original Message ----- 
From: "Eugene Hertz" <ehertz at tcaf.org>
To: <premium-rx at ml.skirrow.org>
Sent: Tuesday, October 19, 2004 7:13 PM
Subject: Re: [Premium-Rx] spectrum Analyzer to use as a signal monitor


> Anyone play with this? (aor sdu)
>
> http://www.universal-radio.com/catalog/misc/0114.html
>
> Anyone know of a circuit that can convert the IF output on 455Khz up to 
> 10.7Mhz? I guess I would be losing bandwidth....any thoughts?
>
> Eugene
>
>
>>-----Original Message-----
>>From: Mark Donaldson [mailto:wa1qhq at yahoo.com]
>>Sent: Tuesday, October 19, 2004 04:29 PM
>>To: 'Jacobi Ilan-BIJ001', premium-rx at ml.skirrow.org
>>Subject: Re: [Premium-Rx] spectrum Analyzer to use as a signal monitor
>>
>>I've used an 8553 on a WJ-8718 and found it cumbersome
>>to use. Problem is tuning to the IF center frequency
>>and then reducing the span to something useable for
>>spectrum monitoring, perhaps 20 KHz and keeping the
>>center frequency where it needs to be. Once you have
>>it on it is fine but as soon as the spectrum goes out
>>of frequency lock, you have to repeat the whole
>>process over again. You actually have to try this to
>>appreciate what I am trying to say. It would be easier
>>to do with a spectrum analyzer with a digital
>>frequency readout that has a synthesized LO. I would
>>look for a panadapter at the proper IF frequency.
>>
>>
>>--- Jacobi Ilan-BIJ001 <BIJ001 at motorola.com> wrote:
>>
>>>
>>> Hello dear group.
>>>
>>> I have the HP-8553B/8552B spectrum analyzer.
>>> I would like to know what would be the optimal way
>>> to use
>>> It as a signal monitor for the WJ-8888B Radio.
>>> Appreciate your help.
>>>
>>> Ilan 4X6MU.
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
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>>>
>>
>>
>>
>>
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>
>
>
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