Using Icom R7000 as total power receiver

[Dave Cohen]

Hi group,

Does anyone have insight on the best way to use the Icom R7000 receiver as a total power receiver for continuum RA at 408 MHz? From the research I have done on the topic, I am aware of the following possibilities:

1. Use the 10.7 Mhz IF output available on the rear jack of the receiver - if I do this, what is the best detection method? 
2. Use the audio output of the receiver, and feed into PC soundcard - lots of processing software options here, if this is a valid method.
3. Tap into the signal to the S-meter and feed into integrator/amplifier.
4. Tap into the AGC signal and feed into  integrator/amplifier.

I have already installed the AGC disable switch modification that is popular for this receiver.

Any thoughts on this would certainly be appreciated.

Thanks,

Dave

[David Ocame]

Using the audio output is simple, straight forward and easy as long as the AGC is disabled. This has always worked well for me in the past.

\GL

Dave

 

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Dave Ocame, WS1ETI

Stony Creek Observatory
FN31og
-72.834 longitude
41.272 latitude

Member: The SETILeague, Inc. (Awards Chair),
The Society for Amateur Radio Astronomy (SARA),
The International Trumpet Guild, Shoreline Jazz Collective, and
The Connecticut Symphonic Winds

---

From: Dave Cohen <weze...@gmail.com>
To: sara...@googlegroups.com
Sent: Thursday, January 5, 2012 11:47 AM
Subject: [SARA] Using Icom R7000 as total power receiver

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[jan lustrup LA3EQ JO28XJ79fx]

I use the audio output with AGC "off".

I also use a small audio transformer to kill any ground loops, and diode rectifier --> 2.2MOhm metal resistor-->4.7uF cap to ground ( "intergration" or realy a lowpass filter.).

This dc signal goes to a dual op amp "TL-082" (for 10-30X gain and offset) and then to Labjack 12bit A/D --> radioskypipe logger.

Works fine as a total power radiometer or to made hydrogen line scans.

 

Jan Lustrup, LA3EQ

Norway

 

ps my receiver setup uses a Kenwood TS-2000X transceiver with homemade converters and ULNA's.

[Malcolm Mallette]

 

I would use the 10.7 MHz output which has a IF bandwidth of about 6 MHz followed by a series of wideband IF amps followed by a diode detector and DC amps.

 

The audio output could work but the bandwidth would be very small, even if there is a AM filter in the receiver. Audio reception at AM uses a bandwidth of 10 Kc max and 2.5 Kc for sideband. Very narrow for a total power receiver.

 

On the other hand, you may have interference with the wide bandwidth at 408 Mhz. You could try audio and then the 10.7 Hz output followed by IF amps and a detector and Dc amps. You would find out which works best with your antenna and the interference in your area.

 

First you may want to check out the interference in the 6 Mhz around 408 Mhz.

 

Malcolm

 

 

 

 

 

 

 

Malcolm

 

 

From: Dave Cohen

Sent: Thursday, January 05, 2012 11:47 AM

To: sara...@googlegroups.com

Subject: [SARA] Using Icom R7000 as total power receiver

 

[ARNO...@aol.com]

Hello ,

I would use  an IQ demodulator as "softrock" at the 10.7 MHz  and than use spectraview software , with a good soundcard You can than get about 96 Khz bandwidth.I am using this approach since yeras with an AOR 3000

 

regards Wolfgang , Dj3qd

[James Abshier]

Dave,

When using the 10.7 MHz IF output, be aware that this output has +9
volts DC on it to power a TV adapter that can be connected to it.
Unless you want to use this +9v for your IF amplifier, a DC blocking
capacitor should be used between the IF output and your IF amplifier.

Also, there is probably not much gain from the antenna input to the IF
output. I use this IF output from an R8500 receiver, and usually
require 70 to 80 dB IF gain to bring the system noise level up to -20
dBm for square law detection. I do not use the entire 6 MHz bandwidth -
only about 200 kHz. If you use the entire 6 MHz, you probably wouldn't
need this much gain, but, as Malcolm mentioned, interference could be a
problem.

Jim Abshier

On Thu, 2012-01-05 at 11:47 -0500, Dave Cohen wrote:
> Hi group,
>
>
> Does anyone have insight on the best way to use the Icom R7000
> receiver as a total power receiver for continuum RA at 408 MHz? From
> the research I have done on the topic, I am aware of the following
> possibilities:

> 1. Use the 10.7 Mhz IF output available on the rear jack of the

> receiver - if I do this, what is the best detection method?

> 2. Use the audio output of the receiver, and feed into PC

> soundcard - lots of processing software options here, if this
> is a valid method.

> 3. Tap into the signal to the S-meter and feed into
> integrator/amplifier.
> 4. Tap into the AGC signal and feed into integrator/amplifier.

> I have already installed the AGC disable switch modification that is
> popular for this receiver.
>
>
> Any thoughts on this would certainly be appreciated.
>
>
> Thanks,
> Dave
>
>
>
>
>