Spectrum Analyzers, VNAs, antenna analyzers etc

[Robert Cochrane]

Before the moderators close this thread down (or introduce their own kit!)
some thoughts from G - land.

For basic testing equipment the best route is definitely to go through
e-Bay and buy 10-15 years old professional equipment.  The "feel" of this
generation is also like the K2, with a similar style of interface.  But it
is much better to use trustworthy suppliers.  We all have some bad stories.

I use a Tek 2445A scope and a Marconi 2019A sig gen bought this way.  Plus
items like an HP step attenuator.

If anyone would like to know some trustworthy guys on UK eBay, write off line.

But almost everything else I use is kit or home brew.  Kit from guys like
Oak Hills. AADE and N0XAS.

The Autek AA is an exception.  It is excellent value for aerial adjustment
- apart from the human interface which is neither cold finger nor cold
brain friendly.

Thanks for the battery saving on - off switch grommet idea.
Has anyone built a sturdy slow motion drive for the tuning?  Let me know!

I'm currently building both an N2PK VNA and a W7ZOI spectrum analyzer adapter.

The N2PK provides both through DUT and bridge capability 0-60 MHz.

It needs a computer with a parallel port which can use pre - XP direct
communication.  There is cheap German software available to work via XP
through a genuine parallel port.  It may not work through  a USB parallel
port emulator.  There is talk of a faster version with slightly lower
dynamic range for real time sweeps.

The boards are still available from Italy. The G3SEK site has details.

You need the courage to tackle SMD and either experience or an elmer to
help check out power supply, etc.  Plus perseverance collecting the
components if you are in the UK.  But this is serious gear for 0 -60MHz at
an amazing price.

The W7ZOI SA kits are still available from Kanga US.  The construction is
through board plus Manhattan.  The IF filter is very fiddly to tune, and
really needs building a low power RF meter as well.

You also need to build an extra narrow crystal filter (which is a learning
curve in its own right) since the basic SA is, like other simple SAs, great
fun but not really valuable as a test instrument.

You must spend a lot of time on RF screening, particularly if a tracking
generator is included.  It is built in modular sub units in Hammond boxes
(Eddystone boxes, as they should properly be called, having been invented
over here) each of which needs its own SMA or BNC connectors and through
caps for power supply and controls.  It also needs a +/- 15v supply.

The metal work means you need a friend with a half inch drill capacity
bench pillar drill too!

And it also helps to have a friend with a professional SA running up to
150MHz to help set it up if you get lost...

So why bother?  Something about amateur radio being "self tuition"?

If you love building instruments as well as radio and want to tackle SMD,
start with the N0SS CW detector for the K2 and move on to the K2PK VNA.

If you want to master RF screening, ladder filter construction and
adjustment and the disappearing skill of RF metal working, build the W7ZOI SA.

And if you are a busy semi- professional or much more interested in being
on air than in building instruments,, build a really, really big, strong,
bench and save up for some of the fabulous solid state professional boat
anchor gear now coming onto the market, through people you trust, on eBay.

Rob M0RAC


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[N8LP]

Good post, Rob. I second what you said. You will find the N2PK a
valuable piece of gear. Software-wise, look at Greg Ordy's Cialog
software which also works with the AEA CIA-HF. As such, it limits the
resolution of some functions to that which is supported by CIA... the
VNA libraries are available, and I'm thinking of writing my own software
for it.

The N2PK is a real challenge if you did not get one of the partially
assembled board sets ;-) Another good practice project is one of the
AmQrp ones, like the Micro908.

A friend of mine has an HP-8754A VNA that cost him a couple thousand
dollars, and he recently built a N2PK... he uses the N2PK most of the
time now, and only uses the HP to occasionally verify his results.

I prefer a used SA as opposed to HB... HP and Tektronix make several
that fill the bill, but I do plan to make my own tracking generator at
some point for the Tek 7L14 I have. The Tek SA fits into a 7000 frame,
and there are also lots of scope modules available for this frame. I
also have a Tek 475 scope for portable work that I bought on eBay, and a
HP8640B signal generator that I highly recommend... there is a military
version for less money that eliminates the phase lock feature, but the
stablility is still pretty good. As you say, verify the source,
preferably a test equipment vendor with close to 100% feedback rating
who will guarantee the unit works fully. It might cost $100-200 more for
this, but it's worth it in reduced hassle.

All that being said, I have an Autek VA-1, MFJ and AEA CIA-HF... all of
which I make use of regularly... and I am thinking about the Italian
analyzer or Micro908. You can't have enough test equipment ;-)

Larry N8LP



Robert Cochrane wrote:

> Before the moderators close this thread down (or introduce their own
> kit!) some thoughts from G - land.
>
> For basic testing equipment the best route is definitely to go through
> e-Bay and buy 10-15 years old professional equipment.  The "feel" of
> this generation is also like the K2, with a similar style of
> interface.  But it is much better to use trustworthy suppliers.  We
> all have some bad stories.
>
> I use a Tek 2445A scope and a Marconi 2019A sig gen bought this way.  
> Plus items like an HP step attenuator.
>
> If anyone would like to know some trustworthy guys on UK eBay, write
> off line.
>
> But almost everything else I use is kit or home brew.  Kit from guys
> like Oak Hills. AADE and N0XAS.
>
> The Autek AA is an exception.  It is excellent value for aerial
> adjustment - apart from the human interface which is neither cold
> finger nor cold brain friendly.
>
> Thanks for the battery saving on - off switch grommet idea.
> Has anyone built a sturdy slow motion drive for the tuning?  Let me know!
>
> I'm currently building both an N2PK VNA and a W7ZOI spectrum analyzer
> adapter.
>
> The N2PK provides both through DUT and bridge capability 0-60 MHz.
>
> It needs a computer with a parallel port which can use pre - XP direct
> communication.  There is cheap German software available to work via
> XP through a genuine parallel port.  It may not work through  a USB
> parallel port emulator.  There is talk of a faster version with
> slightly lower dynamic range for real time sweeps.
>
> The boards are still available from Italy. The G3SEK site has details.
>
> You need the courage to tackle SMD and either experience or an elmer
> to help check out power supply, etc.  Plus perseverance collecting the
> components if you are in the UK.  But this is serious gear for 0
> -60MHz at an amazing price.
>
> The W7ZOI SA kits are still available from Kanga US.  The construction
> is through board plus Manhattan.  The IF filter is very fiddly to
> tune, and really needs building a low power RF meter as well.
>
> You also need to build an extra narrow crystal filter (which is a
> learning curve in its own right) since the basic SA is, like other
> simple SAs, great fun but not really valuable as a test instrument.
>
> You must spend a lot of time on RF screening, particularly if a
> tracking generator is included.  It is built in modular sub units in
> Hammond boxes (Eddystone boxes, as they should properly be called,
> having been invented over here) each of which needs its own SMA or BNC
> connectors and through caps for power supply and controls.  It also
> needs a +/- 15v supply.
>
> The metal work means you need a friend with a half inch drill capacity
> bench pillar drill too!
>
> And it also helps to have a friend with a professional SA running up
> to 150MHz to help set it up if you get lost...
>
> So why bother?  Something about amateur radio being "self tuition"?
>
> If you love building instruments as well as radio and want to tackle
> SMD, start with the N0SS CW detector for the K2 and move on to the
> K2PK VNA.
>
> If you want to master RF screening, ladder filter construction and
> adjustment and the disappearing skill of RF metal working, build the
> W7ZOI SA.
>
> And if you are a busy semi- professional or much more interested in
> being on air than in building instruments,, build a really, really
> big, strong, bench and save up for some of the fabulous solid state
> professional boat anchor gear now coming onto the market, through
> people you trust, on eBay.
>
> Rob M0RAC
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>

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[n6wg]

Regarding the Autek antenna analyzers, M0RAC wrote "Has anyone built a
sturdy
slow motion drive for the tuning?  Let me know!"

Here's one idea.  Find the largest knob that will fit the little shaft and
the
space to the edge of the other knob.
This will give a modest improvement in tuning rate, due to the larger radius
of the knob.

73, Bob N6WG


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