See what the lastest rigs are using to switch front end bandpass filters.
In the 80's my job involved using PIN's in RF modems as low as 5MHz.
Considering their measured performance I modified my TS-940's using those
MACOM devices and they worked well to below 160m and really stepped up the
IP3 as I brought my rigs into work on weekends to run tests.
Last time I looked a few years ago they were no longer available;
everything is SMD these days.
Ulrich Rhode was a customer of my sideline Radiokit business and called
often so we discussed this and he tried them in his TS-440 and then
proceeded to prod Kenwood to make changes in their current rigs back then.
Now everyone does it. He also discussed this in his articles in CommQuart
and/or QEX.
Carl
KM1H
----- Original Message -----
From: "Greg - ZL3IX" <zl3ix@inet.net.nz>
To: <topband@contesting.com>
Sent: Wednesday, February 01, 2012 11:24 AM
Subject: Re: Topband: Receiver protection using PIN Diode technology
> Hi Pete,
>
> The lower limit on the operation of a PIN diode, is not arbitrary, it's
> set by the carrier lifetime of the diode. The carrier lifetime has to
> be longer than the half cycle time at the frequency of operation,
> otherwise the diode stops acting like a PIN, and looks more like a
> regular diode. If that happens, you will thus lose the high IP3
> characteristics.
>
> There are a few PIN diodes available with really long carrier lifetimes,
> but they are not very common. It may be easier for you to use a
> different mechanism for Rx protection, such as reverse biased Schottky
> diodes. You need to set the reverse biasing as a compromise between
> IP3, and providing adequate protection for the Rx.
>
> 73, Greg, ZL3IX
>
> On 2012-02-02 02:16 a.m., Pete Smith N4ZR wrote:
>> Quite by accident, in leafing through K9AY's new magazine I ran into a
>> reference to a surface-mount PIN diode
>> <http://www.skyworksinc.com/Product.aspx?ProductID=857> designed
>> specifically for receiver protection. It begins to block signals at +10
>> dBM, and works by quite a different mechanism than conventional diode
>> limiters, resulting in pretty high IP3. The specified lower frequency
>> limit is 10 MHz, but I wonder if that is arbitrary
>>
>> Has anyone tried this approach to receiver protection on Topband?
>>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1416 / Virus Database: 2109/4779 - Release Date: 02/01/12
>
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|