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> From: "James M. Atkinson" <jm..._at_tscm.com>
> Reply-To: TSCM-..._at_googlegroups.com
> Date: Fri, 24 Mar 2006 23:23:55 -0500
> To: "TSCM-L Professionals List" <TSCM-..._at_googlegroups.com>
> Subject: [TSCM-L] Re: Icom R1500 10.7 Mhz IF-output and UN-blocked
> cellphone-bands
>
>
>
> On the issue of buffering the IF output of a radio. If you tap into
> the RF segment of any radio it is important that you buffer the
> output, not only to minimize the possibility of "Zapping" the radio,
> but also because you will load the signal path and reduce the signal
> sent to the next stage. This also applies to discriminator outputs so
> you don't loose half your signal or more.
>
> When I mod a radio to tie into an IF or discriminator I prefer to use
> a high impedance coupling and not to over amplify the signal, and/or
> use a shielded mini-enclosure. If the mod is going in to one of the
> large radios like a R-9000, R-8500, R-7000, PR-700, MSR, that you are
> going to be using for sweeps then you can through in a little extra
> amplifications and then split the signal by 2 or more and drive
> multiple output devices like TWO spectrum displays, or an
> oscilloscope, a demodulator, and two spectrum displays all at once.
>
> Instead of rolling my own, I would like to see is someone come up
> with a off-the-shelf clean buffer circuit that gives you three
> separate high impedance inputs, that amplifies, and divides to four
> channels each for a total of 12 outputs. This way you can drop it
> into pretty much radio, and pick off whatever combinations of signals
> you need to look at.
>
> The R-1500 is a bit crowded inside, and the surface mount components
> require a delicate hand. Even with the tight quarters it is a great
> radio to modify but those limiter diodes on the front end create most
> of the birdies. The switching PIN diodes also are not the cleanest
> and most isolating they could have used but a couple of diode mods
> will drastically reduce birdies and inter-modulation distortion problems.
>
> -jma
>
>
>
> At 07:35 PM 3/24/2006, cont..._at_yahoo.co.uk wrote:
>
>> For your Icom PCR-1500 information you may want to check:
>>
>> http://groups.yahoo.com/group/ICOM-IC-R1500
>>
>> If you need a 10.7 Mhz IF-output on the spot
>> i can do it for you at 200 US$ (excl transport)
>> Problem might be that i'm in Europe,
>> instead i could supply a new one that
>> i buy here and add the 10.7 Mhz output to it
>> and then send it to you.
>>
>> [snip]
>>
>> If you want i could also add a 450 Khz output to it
>> wich could be usefull for other things like for example subcarrier
>> demodulation.
>>
>> Adding additional outputs is more then just adding a wire
>> ..if done bad it will cause additional birdies on your scanner
>> ..if not buffered it might zap the IF-signal and cause other problems.
>>
>>
>> contranl
>
>
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> James M. Atkinson Phone: (978) 546-3803
> Granite Island Group Fax: (978) 546-9467
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> Gloucester, MA 01931-8008 Email: mailto:jm..._at_tscm.com
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Received on Sat Mar 02 2024 - 00:57:21 CST