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

[Chuck Hutton]

That's not the idea I have, for whatever that means. As I see it, the
diplexer design is driven by the frequencies of the IM products generated by
the mixer and the bandwidth of the filter is not part of the design per se.

Chuck

-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Carcia, Francis A HS
Sent: Tuesday, February 08, 2005 10:31 AM
To: premium-rx at ml.skirrow.org
Subject: RE: [Premium-Rx] Ten-Tec RX-340 - Amateur Use

The tighter the filter the more you need a good diplexer. Easy to build
though.

-----Original Message-----
From: John Miles [mailto:jmiles at pop.net]
Sent: Tuesday, February 08, 2005 12:55 PM
To: premium-rx at ml.skirrow.org
Subject: RE: [Premium-Rx] Ten-Tec RX-340 - Amateur Use


Keep in mind, too, that simply adding a 3-kHz filter after the first mixer
does not guarantee improved real-world performance.  You may also need a
diplexer after the first mixer to present a 50-ohm (or whatever) load across
the board.  A mixer that isn't terminated in a *broadband* load won't be all
it can be in the IMD department.

-- john KE5FX

>
> First, as I mentioned, making a narrow filter at high frequencies is not
> trivial.  You think paying $100 for a typical 9 MHz xtal filter is bad...
> try and price a 40.455 3 KHz xtal filter!
>
> And I can think of many receivers costing much more than the TenTec that
> don't have them either.
>
> > Tell me then, why don't all high end HF rigs have this capability?  The
> > Ten Tec 340 roofing filter mod looked pretty straight forward and
> > inexpensive (using a KIWA 4 kc filter).  Others have done this
> mod and are
> > happy, but I wasn't due to the loss of fidelity.  Guy Atkins and I had
> > problems when we tried added a switch to the mod.  Somewhere along the
> > line we lost a lot of signal strength, which was not the case if the
> > filter was wired in permanently.  I've been wondering about
> this problem
> > for quite a while.  I don't understand why a $4k receiver (ie the 340)
> > wouldn't have such a capability.  I re-iterate again that the
> Ten Tec is a
> > bit of a dog on MW in it's unaltered state.......Walt.
> >
>


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