[R-390] R-390A On 160 Meters

[Bill Breeden]

I agree with Don that you have to be aware of the effect that a multicoupler 
may be having on the results of such a comparison.

I have my multicoupler wired so that I can cut it in and out as Roy has 
suggested.  I use the receiving antenna switch on my FT-920 transceiver to 
accomplish this.  The FT-920 has receiving antenna input and output 
connectors that allow a receiving converter or other device to be inserted 
in the signal path to the receiver.  When I select the receiving antenna 
function, the antenna connected to the transceiving antenna connector is 
routed to the receiving antenna output as long as the FT-920 is in receive 
mode.  I have the receiving antenna output on the FT-920 connected to the 
input port on the MCA104 multicoupler.  So that the FT-920 can still hear in 
this mode, I have one of the output ports on the multicoupler connected to 
the receiving antenna input on the FT-920, leaving 3 output ports on the 
multilcoupler available for other receivers.  Any time I think there might 
be an issue with the multicoupler or a spurious signal from one of the other 
receivers, deselecting the receiving antenna function on the FT-920 cuts the 
multicoupler and the other receivers out of the circuit.

Bill - NA5DX


> Message: 1
> Date: Tue, 24 Feb 2009 12:29:41 -0500
> From: Roy Morgan <k1lky at earthlink.net>
> Subject: Re: [R-390] R-390A On 160 Meters
> To: 2002tii <bmw2002tii at nerdshack.com>
> Cc: r-390 at mailman.qth.net
> Message-ID: <E965FAA5-6713-4CA3-93EA-983A33970866 at earthlink.net>
> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>
>
> On Feb 23, 2009, at 11:16 PM, 2002tii wrote:...
>> Don't discount the effect the multicouplers may be having on the
>> results.  The output-to-output isolation is only on the order of 20
>> dB ...the ones I've
>> measured have been significantly worse -- around 10-12 dB ...
>> Distortion in
>> the multicoupler amp can spread the junk all over the bands, ...
>
> Don,
>
> Thanks for the real world numbers on the multicouplers.  I have a
> military one sold by the surplus folks in Canada before they
> disappeared.  It's an RCA CU-5069/FRD-10A - apparently a lot of them
> were made by TMC for RCA in Canada, or the other way around. This unit
> is a pretty early solid state unit, and I'd expect it's performance to
> be poorer than the ones you report on.  For info, see:
> http://skirrow.org/Boatanchors/TechTalk6.pdf
>
> I also have an older military unit that uses 12AT7's for the amplifiers.
>
> An interesting experiment would be to do an IN-OUT comparison with
> some weak signal, or with a busy band to see how a multicoupler was
> degrading the signals.
>
> Sooo many projects, sooo little time.
> Roy
>
> Roy Morgan
> k1lky at earthlink.net
> 529 Cobb St.
> Groton NY, 13073