Topband: HMC580 instead of W7IUV preamp

[Mike Waters]

That's an interesting idea.

However, in this rural QTH in SW Missouri, there are no AM BCB stations
closer than 40 or 50 miles. And none of those are over 5 kW. No nearby hams
on 160m. And on top of that, we have directional Beverage antennas that can
feed an optional preamp with the W7IUV modifications,
www.w0btu.com/W0BTU-broadband-preamps.html .

I have never had to use any type of high-pass or band-pass filter on 160.
Here, IMD is not an issue (unless I have my noise blanker set too high ;-)

If I decided to build a WF, a low noise figure seems to be more important
than a preamp with as high an intercept point as possible.

With all of that in mind, any suggestions for a very low noise figure,
high-gain preamp with only a modest IP3 spec for a WF?

73, Mike
www.w0btu.com


On Wed, Sep 9, 2015 at 4:35 PM, Richard (Rick) Karlquist <
richard at karlquist.com> wrote:

>
>
> On 9/9/2015 4:04 AM, Andrew Ikin wrote:
>
> Both amps, being single ended are likely to be susceptible  to second
>> order IMD from BC AM band Tx. Whether one would notice much difference
>> with a amp. with a less than 1dB NF versus the above mentioned types
>>
>
> It would not be hard to use two HMC-580's in push pull with
> input and output transformers.  The output transformer could
> be used to feed in the DC, eliminating the RF chokes.  This
> should improve second order IMD by 20 to 40 dB, depending
> on how well matched the amplifiers are.  It would also increase
> 3rd order intercept by 3 dB.
>
> Rick N6Rk
>
>