[ARC5] Selective Level Meters

[Richard Knoppow]

     You might want to look at the specs of the Hewlett-Packard 321B 
selective voltmeter.  The specs give noise floor and rejection of 
spurious responses. These work very well as LF receivers.  There are 
later versions but I think the earlier handbook is worth looking at.

On 6/5/2016 12:05 PM, commtekman--- via ARC5 wrote:
> 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
> <mailto: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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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL