[ARC5] Selective Level Meters

[commtekman at aol.com]

Hello,
I was following your discussion on SLM usage. I used one on my job in addition to a lot of other pieces of test equipment when checking levels of multiplex channels riding on a Collins microwave system. They are very sensitive and selective when set on a narrower bandwidth. Sorry to butt in-

Bob
K6OSM


 

 

 

-----Original Message-----
From: Chris Bowne <aj1g at sbcglobal.net>
To: Robert Eleazer <releazer at earthlink.net>
Cc: <arc5 at mailman.qth.net> <arc5 at mailman.qth.net>
Sent: Sun, Jun 5, 2016 11:03 am
Subject: Re: [ARC5] Selective Level Meters



I have not delved into the details of my W und G AT-611 re RF preselection, other than to know it has a selection of the type of source impedance which includes 
75 ohm unbalanced and a couple of higher impedance balanced inputs.  It also has a 75 ohm unbalanced "bridged" mode, which I assume is a high impedance input mode to minimize loading of the source being measured. In other than the bridged mode the source appears to be looking at a non-reactive 75 ohm load or the others identified on the front panel which I can't recall at the moment.  It plays very nicely as a receiver using nominal 50-75 ohm coax fed antennas at their resonant frequencies.  I found out that when using it at VLF with an HF antenna the signals and noise levels are about 20 dB higher with the bridged input than the standard 75 ohm unbalanced input mode.  I have not yet observed any problems with receiver cross modulation overload from strong signals.  It is extremely sensitive and so far appears crush proof. Depending on the frequency it operates as either a triple or quad converision superhet with a LSB/USB selectable product detector and nominal 2.7 or 0.4 kHz bandwidth filters.  No envelope detector for AM reception but I imagine it would be easy enough to add one and disable the BFO.  Because of its purpose it has NO AGC.  It's really amazing how much fading goes on on an AM carrier on HF frequencies when I use the W und G to look at carrier levels while using another receiver with AGC  for the actual listening.  


73 de Chris, AJ1G.



Sent from my iPhone

On Jun 5, 2016, at 13:08, "Robert  Eleazer" <releazer at earthlink.net> wrote:



A while back some folks mentioned using selective level meters (e.g.,AT-611) as LF-MF-HF receivers.  I looked into those devices a bit and found that they do not have any preselection.  I suppose that makes sense considering their original function, but do y'all that use them add at least an "antenna tuning stage"?
 
Thanks

Wayne
WB5WSV


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