Re: Topband: HMC580 instead of W7IUV preamp

[Mike Waters]

Update: it now looks like increasing the current DOES degrade the NF.

The Motorola LT1001A datasheet (now linked to from my preamp page)
indicates that. I couldn't find a similar datasheet for the 2N5109.

73, Mike
www.w0btu.com


Does anyone want to make an educated guess as to how W7IUV's emitter
> resistor modification may have affected the NF?
>
> My guess is that the NF was changed little if any. I'm sure it helped the
> signal-handling capability.
>
> The only transistor I've ever used in that circuit is a TRW LT1001A. It
> had slightly better specs than the 2N5109.
>
> The original schematic is at
> www.w0btu.com/W0BTU-broadband-preamps.html and the transformer I used in
> the photos was W8JI's idea (in the early 1980s).
>
> 
>
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Re: Topband: HMC580 instead of W7IUV preamp

[Mike Waters]

Does anyone want to make an educated guess as to how W7IUV's emitter
resistor modification may have affected the NF?

My guess is that the NF was changed little if any. I'm sure it helped the
signal-handling capability.

The only transistor I've ever used in that circuit is a TRW LT1001A. It had
slightly better specs than the 2N5109.

The original schematic is at
www.w0btu.com/W0BTU-broadband-preamps.html and the transformer I used in
the photos was W8JI's idea (in the early 1980s).

73, Mike
www.w0btu.com
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: 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 <
rich...@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
>
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: HMC580 instead of W7IUV preamp

[Richard (Rick) Karlquist]

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

_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: HMC580 instead of W7IUV preamp

[Andrew Ikin]

Rick N6RK Wrote Sept 9.


Snip


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 with higher NFs is 
debatable. The reason I say  this is; is that the Flag  has a high NF due to 
its termination resistance. With other antenna types the noise due to the 
loss resistance is a minute fraction of the antenna impedance. Hence, this 
noise resistance is mismatch to amp. input z. For example a very low noise 
JFet amp. (Wellbrook ALA100LN) when terminated with a loop antenna will 
provide a 6-8dB lower noise floor compared to the amp. being terminated with 
a resistance equal to its input z.


73

Andrew Ikin

G8LUG


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Re: Topband: HMC580 instead of W7IUV preamp

[Richard (Rick) Karlquist]

On 9/8/2015 7:02 PM, Mike Waters wrote:

Given the recent discussion about the need for low-noise preamps for the
Waller Flag, it would be interesting to learn what the NF on 160 for
this device might be.

It's rated for "DC" up into the GHz range. However, as N4IS pointed out,
a good NF at VHF does not mean a good or better NF below 2 MHz.

73, Mike
www.w0btu.com 



I've characterized this device and can tell you that the 1/f
corner is well below 2 MHz, because it is based on HBT
technology.  The devices that are good at VHF and noisy
at 2 MHz use MOSFET, GaAsFET, or ephemt technology.
JFET devices are also low noise at 2 MHz if they have a sufficiently
low channel resistance.

Rick N6RK
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: HMC580 instead of W7IUV preamp

[Mike Waters]

Given the recent discussion about the need for low-noise preamps for the
Waller Flag, it would be interesting to learn what the NF on 160 for this
device might be.

It's rated for "DC" up into the GHz range. However, as N4IS pointed out, a
good NF at VHF does not mean a good or better NF below 2 MHz.

73, Mike
www.w0btu.com

On Fri, Aug 28, 2015 at 5:26 PM, Richard (Rick) Karlquist <
rich...@karlquist.com> wrote:

> It might be a lot easier to simply buy this amplifier IC:
>
> http://www.hittite.com/products/view.html/view/HMC580ST89
>
> The specs are close to the W7IUV preamp.
> I mounted one of these ICs on a breadboard and tried it out with a short
> vertical whip and it
> seemed to work fine.
>
> Rick N6RK
>
>
>
> On 8/28/2015 2:53 PM, Martin Kratoska wrote:
>
>> The latest version 6
>>
>> http://www.okdxf.eu/files/preamp_r60.pdf
>>
>> 73,
>> Martin, OK1RR
>>
>
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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: HMC580 instead of W7IUV preamp

[Mike Waters]

Thanks, Jeff! Much appreciated.

Looks like it might be a fun winter project.

73, Mike
www.w0btu.com

On Fri, Aug 28, 2015 at 6:24 PM, Jeff Kincaid  wrote:

> DigiKey has some...
>
> HMC580ST89ETR Analog Devices Inc | 1127-1059-1-ND | DigiKey
> 
>
>
> [image: image]
> 
>
>
>
>
>
> HMC580ST89ETR Analog Devices Inc | 1127-1059-1-ND ...
> 
> Find Analog Devices Inc HMC580ST89ETR (1127-1059-1-ND) at DigiKey. Check
> stock and pricing, view product specifications, and order online.
>
> View on www.digikey.com
> 
> Preview by Yahoo
>
>
>
> 'JK
>
>
>
> On Friday, August 28, 2015 3:57 PM, Mike Waters 
> wrote:
>
> That's amazing. But where did you get it? Mouser is sold out, 390 on
> order, but no estimated delivery date.
>
> 73, Mike
> www.w0btu.com
>
>
> On Fri, Aug 28, 2015 at 5:26 PM, Richard (Rick) Karlquist <
> rich...@karlquist.com> wrote:
>
> > It might be a lot easier to simply buy this amplifier IC:
> >
> > http://www.hittite.com/products/view.html/view/HMC580ST89
> >
> > The specs are close to the W7IUV preamp.
> > I mounted one of these ICs on a breadboard and tried it out with a short
> > vertical whip and it seemed to work fine.
> >
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
>
>
>
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Topband: HMC580 instead of W7IUV preamp

[Lee K7TJR]

Mouser has them in other packaging.

http://www.mouser.com/Search/Refine.aspx?Keyword=HMC580ST89ETR

Lee  K7TJR

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Re: Topband: HMC580 instead of W7IUV preamp

[Jeff Kincaid]

DigiKey has some...
HMC580ST89ETR Analog Devices Inc | 1127-1059-1-ND | DigiKey

|   |
|   |  |   |   |   |   |   |
| HMC580ST89ETR Analog Devices Inc | 1127-1059-1-ND ...Find Analog Devices Inc 
HMC580ST89ETR (1127-1059-1-ND) at DigiKey. Check stock and pricing, view 
product specifications, and order online. |
|  |
| View on www.digikey.com | Preview by Yahoo |
|  |
|   |


'JK 


 On Friday, August 28, 2015 3:57 PM, Mike Waters  wrote:
   

 That's amazing. But where did you get it? Mouser is sold out, 390 on order,
but no estimated delivery date.

73, Mike
www.w0btu.com


On Fri, Aug 28, 2015 at 5:26 PM, Richard (Rick) Karlquist <
rich...@karlquist.com> wrote:

> It might be a lot easier to simply buy this amplifier IC:
>
> http://www.hittite.com/products/view.html/view/HMC580ST89
>
> The specs are close to the W7IUV preamp.
> I mounted one of these ICs on a breadboard and tried it out with a short
> vertical whip and it seemed to work fine.
>
_
Topband Reflector Archives - http://www.contesting.com/_topband


  
_
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Re: Topband: HMC580 instead of W7IUV preamp

[Mike Waters]

That's amazing. But where did you get it? Mouser is sold out, 390 on order,
but no estimated delivery date.

73, Mike
www.w0btu.com


On Fri, Aug 28, 2015 at 5:26 PM, Richard (Rick) Karlquist <
rich...@karlquist.com> wrote:

> It might be a lot easier to simply buy this amplifier IC:
>
> http://www.hittite.com/products/view.html/view/HMC580ST89
>
> The specs are close to the W7IUV preamp.
> I mounted one of these ICs on a breadboard and tried it out with a short
> vertical whip and it seemed to work fine.
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: HMC580 instead of W7IUV preamp

[Richard (Rick) Karlquist]

It might be a lot easier to simply buy this
amplifier IC:

http://www.hittite.com/products/view.html/view/HMC580ST89

The specs are close to the W7IUV preamp.
I mounted one of these ICs on a breadboard and
tried it out with a short vertical whip and it
seemed to work fine.

Rick N6RK



On 8/28/2015 2:53 PM, Martin Kratoska wrote:

The latest version 6

http://www.okdxf.eu/files/preamp_r60.pdf

73,
Martin, OK1RR
_
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