[Premium-Rx] Ten-Tec RX-340 - Amateur Use

Tue Feb 8 12:26:58 EST 2005

Thanks, John

So why are they called roofing rather than skirt??
Is there a symbol for them ala low, hi, bp ?

73
Hank WD5JFR
----- Original Message ----- 
From: "w3jn" <w3jn at direcway.com>
To: "Henry Kolesnik" <kolesnik at sbcglobal.net>; <premium-rx at ml.skirrow.org>
Sent: Tuesday, February 08, 2005 10:57 AM
Subject: Re: [Premium-Rx] Ten-Tec RX-340 - Amateur Use

> Hank, the roofing filter is the FIRST filter after the FIRST mixer. 
> Usually, with high IF designs nowadays, they're 40.455 MHz, 60 MHz, or 
> something similar.  As you know the first filter after the mixer has the 
> most effect on ultimate close-in dynamic range, and these filters are 
> usually on the order of 15-30 KHz in bandwidth.  The higher selectivity 
> filters (3 KHz, 400 hz, etc) are further downstream at the 2nd, 3rd, or 
> even 4th IF.  Thus, any crap that passes thru the roofing filter gets 
> amplified thru the IF chain and the last filter has the unenviable job of 
> having to filter that crap out.   So a strong signal, say 10 KC from your 
> desired signal that yuo're trying to listen to on a 4 KC filter is gonna 
> be amplified by the IF (and it may be strong enough to drive them 
> non-linear) and could even blast thru the last filter if it's strong 
> enough.
>
> Therefore, roofing filters of 10, 6, 3, or even 1 KHz switchable are 
> highly desireable, but not necessarily easy to accomplish at the low VHF 
> region with crystals.
>
> 73 John
>
> ----- Original Message ----- 
> From: "Henry Kolesnik" <kolesnik at sbcglobal.net>
> To: <premium-rx at ml.skirrow.org>
> Sent: Tuesday, February 08, 2005 9:39 AM
> Subject: Re: [Premium-Rx] Ten-Tec RX-340 - Amateur Use
>
>
>> It's clear I'm a little behind.  Can someone please explain the 
>> difference between a roofing filter and a passband filter and why it's 
>> called that? Also what' the difference between selectable roofing filters 
>> and passband tuning?
>> tnx
>>
>> 73
>> Hank WD5JFR
>>
>> ----- Original Message ----- 
>> From: "Cecil Acuff" <chacuff at cableone.net>
>> To: "Carcia, Francis A HS" <francis.carcia at hs.utc.com>; 
>> <premium-rx at ml.skirrow.org>
>> Sent: Tuesday, February 08, 2005 8:13 AM
>> Subject: Re: [Premium-Rx] Ten-Tec RX-340 - Amateur Use
>>
>>
>>>I believe the Ten-Tec Orion has implemented multiple, selectable roofing 
>>>filters.  I would imagine it's in the primary receiver though which I 
>>>also believe is limited to the Amateur bands only.  I'm not sure the 
>>>secondary receiver which is General Coverage takes advantage of that 
>>>technology.
>>>
>>> Don't own one though...
>>>
>>> Cecil...
>>> ----- Original Message ----- 
>>> From: "Carcia, Francis A HS" <francis.carcia at hs.utc.com>
>>> To: <premium-rx at ml.skirrow.org>
>>> Sent: Tuesday, February 08, 2005 7:10 AM
>>> Subject: RE: [Premium-Rx] Ten-Tec RX-340 - Amateur Use
>>>
>>>
>>>>        I find this quite interesting. I think a prepost filter ahead of 
>>>> the
>>>> new SDR hardware will be required. The tuned RF stage
>>>>    in the R390A does a good job of stripping out wide band crud. 
>>>> Multiple
>>>> Roofing filters is an option no receivers have yet
>>>>    have a big effect on performance. I still think the SDR needs a 
>>>> stage of
>>>> conversion to an IF with multiple roofing filters
>>>> ahead of the bit bashing. fc
>>>>
>>>> -----Original Message-----
>>>> From: Walter (Volodya) Salmaniw [mailto:salmaniw at shaw.ca]
>>>> Sent: Monday, February 07, 2005 11:21 PM
>>>> To: Williams, Barry
>>>> Cc: premium-rx at ml.skirrow.org
>>>> Subject: Re: [Premium-Rx] Ten-Tec RX-340 - Amateur Use
>>>>
>>>>
>>>> At 07:20 AM 2/7/2005, you wrote:
>>>>
>>>>
>>>>
>>>> Before I went any further I wanted to check and see if any of the 
>>>> RX-340
>>>> owners had tried the receiver on the ham bands, particularly in a CW 
>>>> pileup.
>>>> It would also be interesting to see if anyone has used the RX-340 to 
>>>> listen
>>>> to a weak AM signal within 10 kHz of a very strong signal.  I did some
>>>> listening tests with my HF-2050 and it appears to work pretty well, 
>>>> even in
>>>> a pileup on 7010.  On the other hand, the filters in the HF-2050 are 
>>>> not
>>>> very sharp as compared to modern DSP filters.
>>>>
>>>>
>>>> Hi, Barry.  I have a Ten Tec 340, as well as a HF-2050, an Icom 
>>>> 756ProII, a
>>>> R390A with a SE-3, and a AOR 7030+ which are often on at the same time, 
>>>> so
>>>> A-B-C-D-E testing is possible.  Of all these receivers, (and this is 
>>>> only my
>>>> opinion), the Ten Tec performs the worst on MW with a strong adjacent
>>>> signal.  The MW dxers out there are well aware of this fact and have 
>>>> gone to
>>>> some trouble installing roofing filters to correct the poor 
>>>> performance.
>>>> For the longest time, I A-B'd the 2050 and the 340 and virtually in 
>>>> every
>>>> instance, the 25 year old 2050 out gunned the 340 by a long shot.  I 
>>>> was all
>>>> set to sell the 340, but it's performance on HF is really very good, 
>>>> and
>>>> with ERGO4 computer control, it's a very nice set up.  The 7030+ is an
>>>> excellent performer in close, as is the 756, and of course nothing 
>>>> seems to
>>>> bother the old Collins R390A.  I know several of my MW colleagues have 
>>>> added
>>>> the roofing filter on the 340 which improves the performance markedly, 
>>>> and
>>>> they seem very pleased, but at the price of losing the wide audio 
>>>> bandwidths
>>>> available in the 340..........Walt.
>>>>
>>>>
>>>
>>>
>>> --------------------------------------------------------------------------------
>>>
>>>
>>>> _______________________________________________
>>>>
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>>>>
>>>
>>>
>>>
>>> _______________________________________________
>>>
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>>>
>>
>>
>> _______________________________________________
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> 