Initial Receiver Tests - Mercury HPSDR vs: FT-1000D

[w3jn]

They're available from time to time, Tom, keep an eye peeled on eBay.

The BCD input interfaces with the RF-590 receiver or RF-1310 exciter.  It's fully usable on its own with the decade knobs though.  Selectivity is 10% at -60dB.

[WA1GFZ]

551 is a cool box. Also there is a tunable preselector module that goes inside the 590. Some 551s come with decade switches on the front panel.
I have powered up my cubic and it works quite well.

[Steve - K4HX]

Keep in mind, even a 5% BW is still 700 kHz at 14 MHz. So, the preselector will do little or nothing for strong signals within the 20 meter band.

[WA1GFZ]

right but it will beat the crap out of a signal in the BC band or 10 MHz away.
Tom, La Pointe made a high Q preselector in a 3 foot rack. it was very sharp. I worked on the prototype  and it was very cool. It went on the deck of a ship. It had a wip antenna but we built adapters for coax input for testing and tuning. You could tune it from a remote control box. Imagine a couple of them into a pair of mercury receivers.
It had 1/4 inch copper tubing silver plated inductors.

[Steve - K4HX]

If those take out your RX, it's junk.

right but it will beat the crap out of a signal in the BC band or 10 MHz away.
Tom, La Pointe made a high Q preselector in a 3 foot rack. it was very sharp. I worked on the prototype  and it was very cool. It went on the deck of a ship. It had a wip antenna but we built adapters for coax input for testing and tuning. You could tune it from a remote control box. Imagine a couple of them into a pair of mercury receivers.
It had 1/4 inch copper tubing silver plated inductors.

[WA1GFZ]

well yes we are talking about the ft1000 but again you should see the flex 5000 freak out at w1aw and local bci

[K1JJ]

Maybe W1AW is getting beat up with WPOP, 5KW about a mile? away. And WTIC, 50KW maybe 5 miles?


Steve, about the 5% BW.  Lets say it's down 60db 700 khz away.  What would that roughly equate to at 50khz, 100khz  or 200khz away, 5-10db or so?  Maybe there is some small value on the same band if the offender is far enuff away.

Frank, a 3' high rack preselector? Sounds like a beast even Vortex Joe wouldn't haul into his cellar...

Maybe I'll look into a simple triple 365 variable section cap and two coils for a multi pole filter, just like a tube RX front end..

T

[KM1H]

Ive been using 2N5109 Nortons for about 30 years here, its one tuff transistor especially when you clip on a heat sink and push the current up.

Im using remote tuned PP U-310's in the 2 turn loops made from 1" CATV hardline and they have been fine, however the Q is very high and the tuning is sharp so overload has been impossible.

[WA1GFZ]

Yup, bias them up to about 60 ma each and use the large 3 fin radiator

[K1JJ]

Anyone have a workable circuit to build up?

[W1AEX]

Anyone have a workable circuit to build up?

This one was passed to me by a friend who has had very good luck with the 5109.

http://w7iuv.com/preamp50/preamp_r50.pdf

I'd like to put one at the feedpoint of each of my receive loops. There is a simple BCB reject filter circuit near the end of the pdf unless you are inclined to pursue the preselector path.

[Steve - K4HX]

There are several nice ones on that CD I gave you.

Anyone have a workable circuit to build up?

[WA1GFZ]

Rob, Those amps will work ok but a norton will have higher dynamic range and less gain. I really like the push pull norton  set at about 10 dB of gain. Biased at 60 ma and you have to be careful because it will also make some power

[K1JJ]

For the Mercury, I'm curious why I need gain and an active device which gives away dynamic range and reduce IMD cleanliness?  Isn't the exisiting built-in preamp enough gain?   I was thinking of just three (inactive) tunable ganged L/C circuits in cascade. This shouldn't have much insertion loss I wud think.

I see Carl used two turns of 1" alum hardline as the coil. A super high Q with large caps seems like a winner for selectivity.

If I'm wrong then kick me in the GDB next time you're in Jersey.

T

[K1JJ]

BTW, on the subject of HPSDR, Mercury and receiving diversity, here's a post from a NE guy (Joe/K1RQG, a HossTraders founder) who uses Mercurys in diversity. He has some results that may interest guys with smaller lots or looking to do a big vertical array with null steering.


T


----------
David and all
 
I have been using K5SO diversity software for quite some time now, months, and
during this time I have transitioned from using 2 horizontal antennas (80 meters),
to using 3 selectable RF probes. I am trying to document the hardware aspect of
my setup and let the software speak for itself.
 
I am still experimenting with different antennas at this time, but bad weather has
slowed my progress. My initial tests with the 2 horizontal antennas on 80 meters
proved to be quite effective bringing DX signals "out of the noise" certainly by
minimizing louder signals from a different direction. Also found it quite effective
to eliminate "birdies" and "UFOs" caused by switching power supplies etc.
 
I have since gone to using 3 RF probes set up in an equal lateral triangle about
50 feet apart. These probes are nothing more than 3 inch square pieces of
double sided PC board connected directly to a high impedance unity gain
amplifier feeding RG-6 back to a software selectable (ALEX control) switching
system that not only provides any two of six selectable inputs, but also provides
RF protection for the Mercury boards. (The RF probes are about 20 feet in the air)
 
The beauty of the RF probes is that they are NOT resonant, and believe it or not,
they perform much better than any of my wire antennas in the Broadcast band
and work well from about 300 Khz to 20 meters.
 
During the daytime, I can null a local broadcast station (13.5 miles away) by more
than 50 dBm and this holds pretty steady. However as time progresses into
darkness and ground wave starts to fade and sky wave increases, the null goes
down somewhat to around 30 dBm.
 
Using diversity at night on 160 and 80 meters varies with propagation, and using the
same probes, I see anywhere from 10 dBm to 25 dBm null, but this is very dynamic
given the variations of the received sky wave.
 
My plan is to try some larger (20 foot) probes and evaluate them when the weather
allows. Then I will try 3 resonant verticals as well.
 
I find I use the RF probes on 80, 40 and 20 meters more than I use the full sized
antennas. They are very useful on 20 meters when I am talking to Europe and
NA stations at the same time, as I can rotate the diversity control to "peak" up
the station in one direction and just click 180 shift for the other. I do run full legal
limit on these bands, thus the need for protecting the Mercury boards even though
the RF probes are 100 yards from my transmit antenna.
 
In conclusion, I find the diversity software extremely useful, and intriguing to experiment
with. I also would like to hear from others about their experiences and how they
use it. If anyone has any other questions regarding my set up, I will be happy to
respond.
 
I want to thank K5SO & W5WC for their continuing improvements of the PowerSDR
software as applied to HPSDR, and of course thanks to FLEX radio and KD5TFD as
well.
 
73 de Joe
K1RQG

[Steve - K4HX]

Cool stuff. I wonder how long it will be until they add this option for transmit?

[WA1GFZ]

Tom you don't need any extra gain unless a preselector ahead of mercury has a lot of loss. This will depend on the configuration and Q of the preselector you use. Many guys have been playing with series tuned circuits rather than parallel tuned tanks. I don't know which one is better. I have a QEX article somewhere by the guy in UK who is selling them. I would like to see what Steve sent you.
I've had a couple emails with Dallas Lankford the past few weeks and he is now using small loaded loops and prefers them over probes. You can't rotate a loop pattern though.
That 3 foot preselector had a vertical on top of it. three would be very cool

[KM1H]

Tom, Im using 3 365pf TOKO varicaps in parallel and running the DC down the feedline. The coil is 1" Trilogy which uses poly spacers instead of continuous foam, it has the least C per foot. Its probably overkill and regular foam hardline would be OK for most users. Solid dielectric cables such as RG-8/58 have too much C and really ruin the Q; those are better for the casual or dimbulb SWL/BCL

[Steve - K4HX]

Why is coax used at all? You can easily make coils with a Q over 200 from wire. Some guys are making loading coils appraoching Qs of 600.

Tom, Im using 3 365pf TOKO varicaps in parallel and running the DC down the feedline. The coil is 1" Trilogy which uses poly spacers instead of continuous foam, it has the least C per foot. Its probably overkill and regular foam hardline would be OK for most users. Solid dielectric cables such as RG-8/58 have too much C and really ruin the Q; those are better for the casual or dimbulb SWL/BCL

[KM1H]

You have examples of these wire claims for loops?

[Steve - K4HX]

Wire loops? Coils. I'm talking about an LC preselector. Talk to W6ANR, W7ZV, W6KW about hi-Q coils. All these guys are using them as loading coils in their transmit antennas. W6ANR claims a Q of 650. If he was FOS, it would have been exposed by now. Measurements on numerous coil types at the link below.

http://www.w8ji.com/loading_inductors.htm

[K1JJ]

http://www.herostechnology.co.uk/pages/tiny_SCR_preselector.html

Check out this preselector from the UK that will work with HPSDR remotely.  Costs about 120 British Pounds. 160-10M, no 6M though.  Tiny, not like a 3' high rack... :-)

Frank found it yesterday.   It might do the trick.  Notice the other offerings at higher prices.

T

[WA1GFZ]

Tom,
It looks like they have another model coming out soon. They did a QEX article on the design and would be easy to duplicate if you wanted to tune manually. Heck you could gear a variable inductor to a variable cap and do the same thing. The trick is they transform down to a low Z and go through a series tuned circuit then a second transformer to get back to 50 ohms. The specs look pretty good until you get to the highest band which seems a bit broad. Two filter sections with a push pull low gain Norton in the middle would kick butt. A kit would be easy to build.
I bet my MSR6300 is better.
The cool thing is it can be set up to track Power SDR

[KM1H]

There is nothing new there about solenoid or toroid coils. Ive been using Q Meters at work or home since the early 80's and others found similar long before that.

What I was referring to is a balanced receiving loop and you will never get high Q with the over the counter RG stuff.

[Steve - K4HX]

OK. I thought you were talking about a coil. You're making an coax loop with a split shield, right?  Wouldn't you get just as high a Q with a wire/copper tubing loop?

There is nothing new there about solenoid or toroid coils. Ive been using Q Meters at work or home since the early 80's and others found similar long before that.

What I was referring to is a balanced receiving loop and you will never get high Q with the over the counter RG stuff.