Questions about a Flex 1500

[K1JJ]

Hi All,

I'm planning to buy a Flex 1500 to use as a receiver and spectrum scope.   I already have enuff transmitters. I own a kit HPSDR TX/RX setup but want to move on to a tiny reliable box with less clutter.

Questions:

1) What is the best software version to use today?  I see PowerSDR around but have heard of other later names too...

2) Is set up as easy as downloading the software in one step, connecting the Flex USB connector to the computer and hooking up an antenna?  (and 13.8V and audio output)  

3) If I were to key the Flex transmitter on, does the receiver spectrum scope stay on so that I could sample some  RF from the 5 watt output to analyze?

4) Has there ever been "Pure Signal" software working with the Flex 1500?  I see an option in the PennyLane HPSDR PowerSDR software for Pure signal, so thought the Flex 1500 might have it too?

Any common problems?

Thanks.

T

[KK4YY]

Hi All,

I'm planning to buy a Flex 1500 to use as a receiver and spectrum scope.   I already have enuff transmitters. I own a kit HPSDR TX/RX setup but want to move on to a tiny reliable box with less clutter.

Questions:

1) What is the best software version to use today?  I see PowerSDR around but have heard of other later names too...

2) Is set up as easy as downloading the software in one step, connecting the Flex USB connector to the computer and hooking up an antenna?  (and 13.8V and audio output)  

3) If I were to key the Flex transmitter on, does the receiver spectrum scope stay on so that I could sample some  RF from the 5 watt output to analyze?

4) Has there ever been "Pure Signal" software working with the Flex 1500?  I see an option in the PennyLane HPSDR PowerSDR software for Pure signal, so thought the Flex 1500 might have it too?

Any common problems?

Thanks.

T

Tom,

1) KE9NS has a full bells and whistles version of PowerSDR.
2) Almost that easy.
3) No. It displays the transmit output, apparently sampled at a low level... not the output.
4) Not that I'm aware of.

Common problem is that it has a transmit spur which, IIRC, is 19khz below CF. It's about 40 dB down, if you're lucky. Not a problem when used as a 5 watt rig but if used with an amplifier it can become an issue. If used as a signal source for a Big Rig, you'll never be able to filter that spur out... it's too close-in.

Good luck, it's a nice receiver. Very versatile for the money.


Don

[K1JJ]

Thanks for the info, Don. Much appreciated.

I was talking to Flex about the Firewire issue. My new laptop computer does NOT have Firewire output. He said there is nothing I can do, so I am compelled to buying a Flex 1500 or a 6000 which does not use Firewire anymore.  It is getting outdated. I have a lead on a 1500, so I will probably settle with that.

Questions:  

1) I was told that AM maximum receive bandwidth was only 8 KHz on the 1500, but I assume that is handled in software by KE9NS, correct? IE, I shud be able to get 16 or 20 KHz receive capability?  

2) Will I get excellent fidelity comiing directly out of the earphone jack (to be amplified) or do I need to tap into the receiver inside?

3) Why are there Flex 5000 radios going for only $800 and Flex 1500's commanding $500?  Am I dumb buying a 1500 when the 5000 is so cheap?  What am I missing?  Even the 3000 is $1000 in some ads.


OK on the -19 KHz TX spur. It's good I will use the 1500 only for receive and watching the spec scope on both RX and TX.  No problem.



Thanks.

T

[KQ6F]

Tom -

1)  The KE9NS software is based on PowerSDR so the maximum AM bandwidth is limited to 16kHz (8kHz audio).  However, I'm told that KE9NS is very responsive to mod requests.
2)  Headphone output audio quality is excellent.  No need to go inside the box.
3)  The Flex 5000 would require a Firewire card that plugs into your laptop.  They are still available.  KE9NS shows which one he's using on his laptop.  See on his webpage.

I had the 5000 and found the PA to have rather poor IMD performance.  But I guess that wouldn't matter in your case since you'll not use it to Tx.

Rod

[KQ6F]

Slight correction -

I forgot about the VAR (variable bandwidth) buttons.  With either one you can open up to a -9999/+9999 bandwidth.  So that gives you 10kHz audio.

[WD5JKO]

Star tech has a Thunderbolt 3 to Fireware adapter. These are pricey, but a used one might be cheaper. Some higher end laptops today have a Thunderbolt 3 port. This allows one to use a Flex 3K or 5K with a modern computer running Windows 10.

Amazon carries this unit:   https://tinyurl.com/vnlm832

PDF attached.

Jim
Wd5JKO

[K1JJ]

Thanks for the info, Rod.


Jim,

At $294, it is more expensive than I paid for my laptop... :-)   I'd be more desperate if I had already bought a 3000 or 5000.

I have a lead on a clean 1500 for about $450 that will use my USB port. It's just for receiving and spec scope use, so I'll just wait on the Anan 200 and Pure Signal transmission until they drop in price…  :-)


T

 

[KD6VXI]

100 or less bucks for a sdr play.

Does everything your asking, albeit rx only.

As well as had a much greater freq range.

I like mine.  USB, and will display 10 mhz at a time


--Shane
KD6VXI

[KK4YY]

After sitting in front of an HP-8563E Spectrum Analyzer at work for a number of years (and knowing I could never afford to buy one myself), I bought the Flex-1500 as a "poor man's" SA and receiver. What a great tool to have on the bench.

And, in a stunning admission...
I also did a few weird things with it. The weirdest has to be the time I tapped its 0dBm transverter I/O into the common T/R IF of a Cobra 138. Fun times.

I'm looking at the SDRplay RSPduo for a future SDR receiver. With two antennas it can cancel local noise, which is a big problem at my QTH. Saving-up my shekels for one.


Don

[K1JJ]

I'm looking at the SDRplay RSPduo for a future SDR receiver. With two antennas it can cancel local noise, which is a big problem at my QTH. Saving-up my shekels for one.
Don

So why aren't I looking at a stand-alone sdr receiver of modern vintage like that rather than paying up for a 2012 era Flex 1500?  I better slow down and think more about this. I am stuck with a USB port, but my laptop computer is pretty fast and of recent vintage.

I realize that PowerSDR isn't the software for these new receivers. PSDR has mucho support. I wonder if this company will stay in biz.  So what is the best under $500 SDR receiver out there for my purpose of a receiver and spec analyzer?   Do an SDR review comparison search and there are tons of receivers out there.  It's like the early days of car manufacturers and most close their doors in the end.  Still, I may end up with one of those like the SDRplay RSPduo you mentioned. (only $295)

T

* I couldn't resist posting the dog shot... :-)

[K1JJ]

$88 shipped for a new Chinese-made SDR receiver.  USB port. It will use SDRuno, HDSDR with RSP1 software.   What is the downside of this?  I only need one tuner. Maybe the dynamic range ain't so good or something else.


What is this radio whirl coming to?  

T


https://www.ebay.com/itm/10KHz-2GHz-SDR-Receiver-Kit-Full-Band-SDR-Radio-Receiver-MiNi-SDR-SDRPlay/383203201143?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D225086%26meid%3D2131d4f367e64aaeb63afcb5a400838d%26pid%3D100005%26rk%3D6%26rkt%3D12%26mehot%3Dpf%26sd%3D293421819158%26itm%3D383203201143%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851

[KK4YY]

If the SDR receiver you buy can tune to the IF frequency of a receiver you already have, then you can use that as a front end for the SDR. Works like a charm.

[K1JJ]

If the SDR receiver you buy can tune to the IF frequency of a receiver you already have, then you can use that as a front end for the SDR. Works like a charm.

I could tap into the I.F. of my FT-1000D.  But doesn't the SDR Play units already have preselectors? Is this for additional image rejection / overload or for something else?

I did a lot of reading tonight on the SDR Play units and I'm going to get one. It's between the RSP1A for $119 and the Duo for $240.  I might try using my Beverage and high loops combined for 75M receiving and see what happens.  I did 75M dual diversity sync'd receivers into Eu years ago and it worked well - but never tried phasing them to enhance the S/N ratio.

Thanks for the SDR Play suggestion. I really didn't need that old Flex 1500 technology at all.  It solves the Firewire problem too.


T

[KL7OF]

file:///C:/Users/User/Desktop/SpectrumAnalyser.pdf
anyone try this?  I haven't but would like to hear from someone that has....

[KK4YY]

file:///C:/Users/User/Desktop/SpectrumAnalyser.pdf
anyone try this?  I haven't but would like to hear from someone that has....

You're going to have to give us a better link than one to your hard drive

[KK4YY]

If the SDR receiver you buy can tune to the IF frequency of a receiver you already have, then you can use that as a front end for the SDR. Works like a charm.

I could tap into the I.F. of my FT-1000D.  But doesn't the SDR Play units already have preselectors? Is this for additional image rejection / overload or for something else?

I did a lot of reading tonight on the SDR Play units and I'm going to get one. It's between the RSP1A for $119 and the Duo for $240.  I might try using my Beverage and high loops combined for 75M receiving and see what happens.  I did 75M dual diversity sync'd receivers into Eu years ago and it worked well - but never tried phasing them to enhance the S/N ratio.

Thanks for the SDR Play suggestion. I really didn't need that old Flex 1500 technology at all.  It solves the Firewire problem too.


T

Given its very small size, I'm guessing that the SDRplay might not have as much bandpass filtering of an FT-1000D. The specs are published if you want to wade through them all.

If you tap onto the IF you could listen through to the SDR, or continue to listen through the FT-1000D and use the SDR as a display only.

The diversity mode is what I'm primarily interested in. How effective it would be, of course, depends on the antennas used. It has an automatic mode and a manual mode for noise cancelling. There are some long-winded videos on YouTube from users demonstrating this. Most of them are about as exciting as an "unboxing" video. Search for "RSPduo diversity" and try not to fall asleep.


Don

[KD6VXI]

The Airspy, Sdr Play and Hackrf all have spec an capabilities.  Some require a firmware update, some don't.

If you don't have a VNA yet, the VNWA also has spec an capabilities.....  And a really good VNA as well (and TDR function, filter measuring, etc...  It's a decade more expensive than the nanovna, but is quite a bit better).

I have both the Hackrf and Sdr Play, as well as a VNWA and Nanovna.  I have used the Airspy, although I don't own it.

All will do what you're looking for.  The vnwa will give a 1.3ghz spec an, and the hackrf gives you full sdr to 6ghz as well as TX support.  Software isn't as easy as the others mentioned.

Just giving more info  to confuse you 😎

--Shane
KD6VXI

[KQ6F]

Also pay attention to the number of bits in the ADC.  More bits = more dynamic range.  Important when using as a spectrum analyzer.

Rod

[KL7OF]

https://www.sdrplay.com/spectrum-analyser/
sorry....
There are a couple others out there that work with sdr play as well....

[K1JJ]

Well, I decided on an SDRPlay for sure.

I watched a lot of the DUO Diversity videos but not impressed. Diversity seems to be good for local noise suppression, (I have none here) but not much when enhancing a signal on the band, most of the time.  Yes, the operators were using tiny dog shit antennas, I must agree.

I think this diversity bell and whistle would get old real fast in real operating and go unused soon.

I will stick with my dual diversity FT-1000D sync'd receivers and use the headphones in stereo with my brain as the integration method. One antenna for each ear works well for me using high loops and bev antennas both beaming NE with a good f-b.   It has a trippy stereo effect much like listening to an FM station.

So a SDRPlay RSP1A singe receiver seems to suit me best. For $120, how can I go wrong?

** BTW, is anyone using front end protection? I see alot of warnings about exceeding -10 to 0 DBM. 

T

[w9jsw]

Give SDR-Console a try for software.

[W2PHL]

The RSP line of receivers are terrific. I have several of them. They're great for SWLing but I don't use them while operating. I find there's too much latency for break-in operation. I made a video to demonstrate.

https://youtu.be/xqpUPcQW1l8

The Flex-1500 is close to real time when using the internal audio from the phones jack and setting the DSP RX buffer to 256. I can also report that the Anan 7000DLE is close to real time when using internal audio and the "low latency" setting in the DSP.

Phil

 
 

[KK4YY]

Nice video Phil, well done.

I've changed the buffer settings and such in my Flex-1500 to get less latency but the sacrifice is passband filter sharpness. A faster computer helps, but you're ultimately limited by how much you can stuff through the radio's USB port. So there's that.

A work-around for doubling caused by latency is to visually monitor an online SDR, watching the display when keying-up. I've seen it happen when I keyed-up, and I quickly unkeyed my transmitter to stop the doubling.

Low latency = high dollars. Ya pays yer money, ya takes yer choice.

[K1JJ]

The RSP line of receivers are terrific. I have several of them. They're great for SWLing but I don't use them while operating. I find there's too much latency for break-in operation. I made a video to demonstrate.

https://youtu.be/xqpUPcQW1l8

The Flex-1500 is close to real time when using the internal audio from the phones jack and setting the DSP RX buffer to 256. I can also report that the Anan 7000DLE is close to real time when using internal audio and the "low latency" setting in the DSP.

Phil

Interesting review, Phil - thanks.   Just when I was about to order an RSP1A...

I wonder why a 2012 vintage radio like the Flex 1500 would have less latency than a modern SDRPlay?  Are you using a fast computer for the SDRPlay?   Is it because of the DUO running two tuners at once vs: a RSP1A having a smaller work load?    I will be using a Win 10 Pro ThinkPad T-430 I5 core with SSD laptop for whatever SDR I end up with.  


Are the other inexpensive SDRs on the market of faster latency? Maybe no one actually sees this latency in stand-alone use and is not aware of it until they use a REAL radio in comparison.    I already have some key-up latency on AM due to an audio delay to kill relay noise, so I don't need any more...  I don't like the idea of monitoring my own signal on the bandscope and socking an "sssss" and see a long delay.

Yes, the USB port is slower and limited. The Firewire is becoming obsolete but is faster.

T

[W2PHL]

I also have an Elad FDM-Duo that is very close to real time when using its internal (inside the radio) sound device.  The latency increases on the Flex, Anan and the Elad when using VAC and or using the PC soundcard.

The RSP1A, RSP2 and the RSP-Duo all seem to have the same amount of latency.

The computer is an i5 4570 16GB with windows 10 but I’ve also run the Flex 1500 on a puny Atom based tablet with the same near real time RX results.

I’ve also tried the RSP(s) on a an i7 9700 and the latency seemed about the same…I didn’t try to measure the difference between the two different computers though.

If you haven’t already guessed it, the common denominator between the ELAD, Flex and Anan is a built-in sound device.

I think it’s great that Bob Allison from the ARRL Lab has been including latency testing in his recent radio evaluations. Latency is an important evaluative parameter, at least for 2-way radio, that’s been somewhat overlooked.