[amsat-bb] Preamps on IC-910

[WB2LLP]

I am trying to improve my satellite receiving capability but find it interesting that I can not find anything in the IC-910 literature that specifies how much current the radio can supply for a pre-amp. It is also interesting to note that they do not specify the current drawn by their pre-amps, or their noise figure.

I want to use ARR preamps but can not determine if the radio can safely supply the 200 ma they want. I would certainly not want to damage the radio trying to improve the hearing. I assume that there is someone on this reflector who is using those pre-amps on a 910 and confirm that it works or does not work.

The other question might be is it safer to power the pre-amps from a separate supply. This might make it safer when reversing the up and down bands.

Gene
WB2LLP

[Alan P. Biddle]

Gene,

Take a look at the following page:
http://www.universal-radio.com/catalog/preamps/icpreamp.html It gives the
draw as 200 ma, which is also in the preamp manual I found on the Icom Japan
web site:
http://www.usersmanualguide.com/icom/accesories__preamplifier/ag35 Since it
(first URL) also list the IC-910 and many other common Icom satellite rigs
as compatible with the preamps, by some property, probably transitivity, it
should also be able to handle the ARR's 200 ma. According to my old notes,
the ARR draws 186 ma @ 13.8 V.

73s,

Alan
WA4SCA

[Dave Aitch]

Hi Adam, Gene.

I didn't see the original note, but if someone is asking
if the AG35 works on the 910, the answer is yes.

I use the 25 and 35 on the 910.

A shame ICOM haven't produced a 23cms pre-amp again.

Cheers,

Dave.

[Steve Meuse]

Post by Dave Aitch
A shame ICOM haven't produced a 23cms pre-amp again.

4db noise factor!

I don't know what they sold for new, but you would be far better off getting the ARR switched or SSB pre-amps.

-Steve
N1JFU

[i8cvs]

----- Original Message -----
From: "WB2LLP" <***@optonline.net>
To: "AMSAT -BB" <AMSAT-***@amsat.org>
Sent: Monday, October 01, 2007 8:14 PM
Subject: [amsat-bb] Preamps on IC-910

Post by WB2LLP
I am trying to improve my satellite receiving capability but find it

interesting that I can not find anything in the IC-910 literature that
specifies how much current the radio can supply for a pre-amp. It is also
interesting to note that they do not specify the current drawn by their
pre-amps, or their noise figure.

Post by WB2LLP
Gene
WB2LLP

Hi Gene, WB2LLP

The sensitivity of the IC-910 in SSB is 0.11 uV for 10 dB S/N and so the
computed Noise Figure is about 4 dB

73" de

i8CVS Domenico

[Scott Townley]

Alan's figures on the icom preamp draw match mine.
FWIW I use ARR mast-mount preamps with my IC-821. Unless something major changed between models.
Also, if you are using the RF-sensing ARR preamps (which the 200mA draw would be), then in one sense you are semi-protected from reversing modes by the RF sense/PTT in the preamp. However, that semi-protection has been known to fail, which is why the weak-signal community is so disposed to sequencers.
Personally (again, on my IC-821) I found it so painful to switch the preamp power from one mode to another than I ended up running preamp power separately and just using lit toggle switches. You have to go into the menu on the '821 to set the preamp power to 2m/70cm/both/none...too many button pushes and opportunities for error.

--
Scott Townley NX7U
Gilbert, AZ DM43di

Post by WB2LLP
I am trying to improve my satellite receiving capability but find it interesting that I can not find anything in the IC-910 literature that specifies how much current the radio can supply for a pre-amp. It is also interesting to note that they do not specify the current drawn by their pre-amps, or their noise figure.
I want to use ARR preamps but can not determine if the radio can safely supply the 200 ma they want. I would certainly not want to damage the radio trying to improve the hearing. I assume that there is someone on this reflector who is using those pre-amps on a 910 and confirm that it works or does not work.
The other question might be is it safer to power the pre-amps from a separate supply. This might make it safer when reversing the up and down bands.
Gene
WB2LLP
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