[amsat-bb] Re: Icom AG-35 Preamp Question

[Lawn, Richard]

You are unfortunately correct and this was not clear in any manuals, at least to me, when I began to use an icom preamp for 435 on my TS-2000. Hence, a blown preamp! There is a guy I found on eBay that sells a switching box that plugs into the external control port on a TS-2000 and gives you a relay control RCA out cable for each of the VHF/UHF bands, even 1.2 if you have it. You can control either amps or preamps. I may look into this, once I figure out how to repair the preamp if it is even repairable, but I think it is.
Thanks for all the input everyone. At the end of the day I wish I had my 847 as I feel it may be a more user friendly rig for sats at least for controlling external preamps.
Rick
W2JAZ


Sent from my iPad
http://RickLawn.com



On Aug 12, 2012, at 8:39 AM, "Mark L. Hammond" <marklhammond at gmail.com> wrote:

> Hi All,
>
> Somebody please clarify---I may be wrong, but I thought the Icom preamps did the following with Icom radios:
>
> In receive, 12V is powered up the coax.  Device is powered, preamp is ON.
> In transmit, the 12 power feed is stopped. Device is not powered, and it's bypassed during xmit.
>
> If this is the case, it complicates greatly the use of Icom preamps on non-Icom radios (means there isn't a typical RF-sensed bypass circuit, which means it would be easy to blow in a non-Icom radio).
>
> Am I remembering this wrong?
>
> Mark N8MH
>
> At 09:30 PM 8/11/2012 -0700, Art McBride wrote:
>> Rick,
>> I suggest you use a VOM or DMM to measure the current drawn on 12 volts
>> going to the power injector. If everything is connected correctly It will
>> draw 30-200 mA. Confirm that you have continuity in your coax. Some
>> lightning arrestors have a DC block built in. It is best to test it with a
>> short run of coax between the preamp and the power injector at the radio
>> while listening to a local repeater to see if the signal increases when you
>> apply power to it. If it operates then you can proceed to determine if there
>> are problems with the coax to the antenna, not carrying the 12 VDC.
>> 73
>> Art,
>> KC6UQH
>>
>> -----Original Message-----
>> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
>> Behalf Of Lawn, Richard
>> Sent: Saturday, August 11, 2012 3:30 PM
>> To: amsat-bb at amsat.org
>> Subject: [amsat-bb] Icom AG-35 Preamp Question
>>
>> I bought an Icom AG-35 preamp about a year ago. The fellow ham advertised it
>> as virtually brand new and it was/is. I planned to use it this summer with a
>> TS-2000 which doesn't supply 12v voltage to the coax to power a preamp as
>> other xcvrs do. I used a Mirage KP2 unit to inject power to the coax to
>> drive mast mounted the preamp. When I turn the power on there seems to be
>> little or no noticeable difference in background noise and worse than that I
>> cannot here any signals on FO-29 downlink, and I know the bird has been
>> active. Any suggestions? Is the preamp fried? I can't even get the weather
>> proof case off to trouble shoot, not that I'd know what to look for. Any
>> suggestions on repair?
>>
>> TNX
>> 73
>> Rick
>> W2JAZ
>>
>>
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