[TowerTalk] Receiver protectors and intermod, harmonics, etc.

[Don Moman VE6JY]

The spectrum is clean (using the Perseus SDR) from any mixing products
until the RG5000 is put in line. Most of the time, the weak signal  lw and
mw spectrum is of interest so I don't want to remove or attenuate it.   The
RG5000 was intended to protect multiple on line SDR's that serve a variety
of remote users on several different sdr platforms.  The Wellbrook serves
as an excellent all band rx loop from 10 khz and upwards and is typically
on 24/7 so wanted to protect the downstream receivers a bit better than my
homebrew diode limiter but not if it produces the mixing products.

73 Don

On Sat, Jul 4, 2015 at 3:56 PM, Tim Duffy <k3lr at k3lr.com> wrote:

> Hello Don:
>
> Where are you placing the RG-5000 in the chain? If the RG-5000 is behind
> the
> Wellbrook active device, that might be an issue - that the mixing products
> are a result of the active amplifier?
>
> Do you use any bandpass filtering to knock down the high RF from the MW
> transmitters?
>
> 73,
> Tim K3LR
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Don
> Moman VE6JY
> Sent: Saturday, July 04, 2015 10:56 AM
> To: TOWERTALK at contesting. com
> Subject: Re: [TowerTalk] Receiver protectors and intermod, harmonics, etc.
>
> Pete, I have the DXE RG-5000.  Altho I am 60km from the nearest mw
> transmitters, I have lots of mixing products across the low bands when it
> is installed, using one of the Wellbrook active loop antennas.  Before this
> I used a home made device with parallel diodes and a small light bulb to
> provide some measure of protection and no mixing issues.  After passing
> thru an passive 8 way splitter, signal levels are in the -20 dbm range
> which should be in their stated  "virtually RF transparent" area well below
> its advertised -10dbm threshold.  It takes another 6 db pad eliminates the
> products.   To use it on one of the low band full size dipoles here would
> be impossible as they produce signal levels in the + a couple of dbm range.
>
>
> 73 Don
> VE6JY
>
>
>
>
> On Fri, Jul 3, 2015 at 7:46 PM, Pete Smith N4ZR <n4zr at contesting.com>
> wrote:
>
> > Do the DX Engineering RG-5000 device, or the AS-RXFEP from Array
> > Solutions) behave nicely when hit with a signal well above their
> protection
> > threshold, or dothey generate interference (noise, harmonics, intermod)
> > from the energy that is blocked?
> >
> > Our particular application is for the RBN, involving a QS1R receiver very
> > close to the antennas of an HF ionospheric radar operating on a couple of
> > discrete frequency bands in the 8-18 MHz range with about 1 KW input
> (don't
> > know what the EIRP would be at the location of the receiver).
> >
> > Dx Engineering says their version offers "far lower harmonic and noise
> > products across the spectrum than any competing RX front-end saving
> > device,"  Would sure like to hear some impartial confirmation.
> >
> > --
> >
> > 73, Pete N4ZR
> > Download the new N1MM Logger+ at
> > <http://N1MM.hamdocs.com>. Check
> > out the Reverse Beacon Network at
> > <http://reversebeacon.net>, now
> > spotting RTTY activity worldwide.
> > For spots, please use your favorite
> > "retail" DX cluster.
> >
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