Several hours ago I posted this inquiry on the TopBand Reflector:
Subject: Topband: Multiple Rcvrs on a Single Beverage
If one were going to use a single Beverage and wanted to use four to eight
receivers with it simultaneously, how would one best split and then amplify
to negate the splitting losses?
A number of you asked to read the responses. Here 'tis and thanks to all=20
involved.
>From <A HREF=3D"mailto:charlesh3@msn.com";>charlesh3@msn.com</A> =20
=20
As for myself, I amplify (usually with an ARR preamp) then split with Mini
Circuits 1:4 or 1:8 splitters (those are the ZFSC series. The particular one=
s=20
I have are the ZFSC-6-110 units which are actually 6 way splitters. You'll=20
find them on MiniCircuits web pages along with all the other different=20
models.) that have BNC connectors. Most of my listening is with Beverages=20
about 1000 feet long and they are used predominantly for MX DXing and I've=20
had no problems with intermod or interactions with other ports.
-0-
>From George, W4BUW
I remember seeing in various Fair Radio ads/brochures a device that was gov'=
t=20
surplus that did just that, allowing several receivers to utilize one=20
antenna.=A0 I do not have details of its construction, but would think that:
1. appropriate splitters would be used to maintain correct antenna impedance=
=20
as the input impedance of the splitter.=A0 This probably meant that unused=20
outputs when not in service had load resistors to occupy the outputs of the=20
splitters to avoid impedance mismatch.
2. each output to the receiver may or may not have in-line amps to make up=20
for the splitter loss, but in the case of multiple receivers, this loss may=20
well be considered insignificant as compared to the rf amplification factor=20
of the front end.
Keep in mind the old military set-up of dual diversity when two separate=20
antennas on receive were used is a common feature of the old SPX-600=20
receivers.=A0 They were even set up such that a single receiver oscillator=20
section could be used on two receivers such that the received signal=20
frequency was the same on both receivers with separate diversity input=20
antennas. These were used in many RTTY set-ups to counter-act the loss of=20
information due to fading of the desired signal.
This may be "food for thought" to utilize two receiving antennas to get the=20
diversity, rather than trying to get multiple receivers to utilize a single=20
antenna.
-0-
>From Gene, AD3F
Check out Array Solutions 111-4A or 112-4A receive signal splitters
(four outputs).=A0 To get eight ports, you'd need one model 111-2A or 112-2A
(two-way splitter) ahead of two of the above splitters.=A0 I'd put the pre-a=
mp
ahead of any passive splitters (the 111-XA models); that way you need only
one amp, not eight.=A0 The 112-XA models have built-in amps, but check the
specs for gain.
-0-
>From John, W1FV
At KC1XX, we had the same issue when we redesigned our Beverage system--in
this case, how to share a Beverage with four receivers.=A0 I came up with a
homebrew solution for a passive 1:4 splitter using 3 toroids.=A0 It is
designed for 50 ohm loads and has the following properties:
See the attachment for a homebrew solution for a passive 1:4 splitter using
toroids.=A0 It is designed for 50 ohm loads. It has the following properties=
:
1 antenna input port.
4 receiver output ports.
-6 dB throughput from antenna port to each receiver port.
50 ohm input termination impedance.
Isolation between receiver ports--short circuit or open circuit condition at
any one receiver port results in no more than ~1 dB level change at other
ports.
If you use a preamp, it should be inserted between the antenna and the
antenna input port.
(John's attachment is a very nice circuit. He'll likely share it with you=20
for a e-mail request <A HREF=3D"mailto:john.w1fv@telocity.com";>john.w1fv@t=
elocity.com</A> )
-0-
=20
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