The narrow Inrad filter people are referring to is a 600 hz lower loss
roofing filter first conceived and implemented for the Orion 565 by W4ZV and
Inrad- and it could be put in either the 1.8 or 1 khz slot. This is done to
avoid activating the extra IF amplifier stage that TT has in place to
correct for the additional loss in their 500 and 250 cycle filters. In fact
the data shows that the IMD performance of the ORION is slightly degraded
when you use the 500 or 250 cycle filter - because of an additional IF stage
to overcome the higher loss of the 250 and 500 cycle filters.
There is no resultant sensitivity issue in either case. It is an ITO/IMD
performance issue.
fwiw -- Hank K7HP
----- Original Message -----
From: <jamesmozzillo@aol.com>
To: <tentec@contesting.com>
Sent: Sunday, October 22, 2006 6:40 PM
Subject: Re: [TenTec] Have questions
> Hi John (KB2HUK):
>
> I do not agree with putting in an Inrad filter at the 1.8 position. I am
> assuming that the 1.8 position is the 1st intermediate frequency of the
> receiver. The reality is it is a trade off. By not limiting the bandwidth
> near the input of the radio, you are allowing your front end to be
> overloaded when a high power signal is nearby. To compensate for this, you
> can use a broad band roofing filter say for 6 or 8 KHz which is plenty
> wide and would minimally reduce sensitivity if at all. But if the ham
> "down the road" turns on his high power linear 300 Hz away from the signal
> you are working on CW a narrow roofing filter will prevent the front end
> of your receiver from overloading. Yes you have reduced your sensitivity a
> bit but you can probably dig the signal out just fine. If you put the
> filter in the next stage of the reciever, you will overload your fron end
> and your AGC will be overloaded and reduce your sensitivity anyway.
>
> The engineers at TenTec have thought of this and designed the Orion
> accordingly. Now Icom and Yaesu have announced that they have put in
> roofing filters in the high priced rigs. Why? Think about this please.
>
> Sincerely,
>
> Jim
> NC9J
>
>
> -----Original Message-----
> From: brazos@rochester.rr.com
> To: tentec@contesting.com
> Sent: Sun, 22 Oct 2006 4:51 PM
> Subject: [TenTec] Have questions
>
>
> Hello , I am currently saving for a nice Orion 1 . I am tiring to get a
> handle
> on what to look for on the used market. I have heard that a radio with
> all the
> optional roofing filters installed actually desensitizes the radio and may
> not
> be any kind of an advantage , and that the slick operator puts in a Inrad
> filter
> at the 1.8 position and this allows closer in sensitivity ? can you
> advise? Am
> I close ? soooooooo confused ! thanks John kb2huk
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