References: <ae0606f0-72b1-f086-a05c-6478c4fa5a41@comcast.net>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>,
        "rsgb_lf_group@yahoogroups.co.uk" <rsgb_lf_group@yahoogroups.co.uk>,
        "Discussion of the Lowfer (US, European, & UK) and MedFer bands"
 <lowfer@mailman.qth.net>
From: N1BUG <paul@n1bug.com>
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Message-ID: <84a03430-6954-f3cd-5437-88045eba51be@n1bug.com>
Date: Fri, 13 Jul 2018 16:43:46 -0400
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Subject: Fwd: [600MRG] LF: Receiver protection - FOLLOW UP
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Reply-To: rsgb_lf_group@blacksheep.org

Some good info on the DX Engineering devices...


-------- Forwarded Message --------
From: Roger Rehr W3SZ

Thanks for an excellent summary, Paul!

I have a few additions to your comments on the DXE device, which I've
used here on 630M with no problems and with excellent results, with
transmitter outputs on the order of 200 watts and with only 20 ft of
separation between the bottom of my inverted L transmit antenna and the
feedpoint of my 500 ft beverage receive antenna.  The device is also
"inline" on my 2200M receive system, but because I haven't transmitted
on 137 kHz I can't comment on it protectional efficacy on that band.

First of all, there are TWO DXE devices, the RG-5000 and the RG-5000HD. 
These have different power-out vs power-in curves at input levels above
-10 dBm. For both of them, however, when tested by the ARRL, it took 10
watts of RF AT THE BNC INPUT CONNECTOR TO THE RG-5000 or RG-5000HD to
produce an output of +13.2 to +13.3 dBm, depending on which of the two
units was being tested.  Below 10 watts of RF power AT THE BNC INPUT
CONNECTOR TO THE RG-5000 or RG-5000HD the output level from the device
is of course less than +13.2 to +13.3 dBm.

Second, although the devices are specified for use at 0.5-150 MHz, the
insertion loss of these devices at 137 kHz may be acceptable for many
users.  The loss is 0.85 dB at 137 kHz for the RG-5000 and 0.81 dB for
the RG5000-HD.  I did not notice a change in my receive performance on
137 kHz from before to after I installed the RG5000-HD.  And "during the
season", I DO monitor my receive performance on both 2200M and 630M in a
quantitative way by examining the previous night's data pretty much
every morning in the manner shown at the URL below.  So I think I would
be more likely than many stations to notice an important change in
receive performance.
http://w3sz.x10.mx/wp/2017/12/13/12-13-17-lf-blog/

The entire ARRL review of these devices, which provides data in both
graphical and tabular forms, is here:
https://static.dxengineering.com/global/images/technicalarticles/dxe-rg-5000_sn.pdf

The excellent 16-page manual for these devices is here:
https://static.dxengineering.com/global/images/instructions/dxe-rg-5000.pdf

I am posting this because I was concerned that some folks who could
really benefit from one of these devices on either the 630M or the 2200M
band might mistakenly discard consideration of them unless they were
aware of the information provided above.

I am very happy with my RF-5000HD and consider the $89.99 I spent on it
to be one of the best purchases I made when setting up my below-500 kHz
stations.

73,

Roger Rehr
W3SZ


On 7/13/2018 7:57 AM, N1BUG wrote:
>  DX Engineering currently markets a similar
> looking device but it is only rated down to 500 kHz and will pass a
> 25 mW signal - well above the stated danger level for some SDRs.
>
>
> 73,
> Paul N1BUG