Two Tone signal input ?

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I recently took delivery on a Telepost LP-500.  I need to connect the two tone signal from the LP-500 to my Flex 6500.

According to the Telepost manual if you use a mic input you will probably have to attenuate the signal and possibly isolate it with a galvanic transformer.

I thought I would try wiring it to pin 1 of the accessory port. This worked expect I can only drive the rig to 1 watt which has little value.

From the manual.

Test Tones: Audio output for built in test tones. 3.5mm mono. Connects to the MIC or LINE input of the rig. An attenuator will be needed in the case of mic input, and possibly galvanic isolation (transformer). Interfaces designed for a sound card based RTTY setup can work for this, but the existing commercial ones that I have tested have some deficiencies.

Line Level... Most rigs have a high Z (10K) line input designed for sound card based digital modes. These inputs work well for the LP-500 test tones. One some rigs they are labeled as line inputs, and have dedicated RCA or 1/8” (3.5mm) jacks. On some rigs they are part of an ACCessory jack or a RTTY jack. These are generally DIN type connectors. Consult your user manual for specifics.

So looking for suggestions on how to do this.  I am using the balanced line input for audio so have that tied up.
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Rich McCabe

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Posted 9 months ago

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k3Tim

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Pin 1 looks correct.
Q1:  Does the "Vu" meter show a reasonable level?

Q2 Is the LPM set to output line level?
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ka7gzr

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I also have an LP-700. I directly input mine to the MIC input. The Mic level does not need attenuation  for the tones in my case.
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Larry - W8LLL

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This is what I did for my Flex 6500 and LP-700. I am getting 80 watts out with the 2 tone.




(Edited)
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Rich McCabe

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Tim,  No the meter does not show reasonable level when connected to pin 1.  It does however on the balanced input.  I don't think Telepost tells you what the actual output level is. I could be wrong.

James,  I might have to use the foster connector for now.

Out of curiosity what does your two tone look like on your Flex?

Playing with something like this is new to me. But this does not look good?

Larry,  as I said above I tried Pin 1 but even with radio power level at 100 watts the two tone will only drive the radio to around 1 watt.
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Larry - W8LLL

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No processor, the ripples grow with output power.



(Edited)
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Rich McCabe

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I have it connected to 7 and 8 foster connector now.  But it works better on the balanced input.

I think it might be better when I get my 6600 as it should have two balanced inputs on the back.

I dont know what to think of the ripples. I would ask Larry what he thinks. 
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Rich McCabe

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Larry,  Just noticed I have more bumps with it on the foster connection even with processor off.
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Larry - W8LLL

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They get worse as the power rises.
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Wayne

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Did you change the input selection to not use the balanced mic when you use the 2 tone signal?
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KC2QMA_John

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Looks like HUM in the audio, Try to connect the shield of the 1/8” cable coming from the LP500 and tie Pin's  5 & 6 together at the foster on the radio. This should do the trick.
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KC2QMA_John

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Pins 5 & 7!  NOT 5&6
(Edited)
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Rich McCabe

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Pins 5&6 or 5&7?
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KC2QMA_John

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OOPS Yes 5 & 7
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Rich McCabe

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No change when connecting pins 5 and 7.

This is from Larry at Telepost.

-10 dBV is 894mV p-p. The output of LP-500 is 350 to 500 mV p-p into a 10K load depending on the test signal, which is roughly 6 dB lower. I would think the input would have a range of plus and minus something relative to -10 dBV, but maybe it's just an attenuator on the input with no gain at all.

I thought my balanced line input looked cleaner but maybe not.


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KY6LA - Howard, Elmer

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@Rich. You got me intrigued. I have. LP700 so I will try the same experiment when I return to the USA next week

Question: looks like u have a power supply hum. Are you feeding both the LP500 and Flex from D.C. Or a linear supply rather than a switching supply?
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Rich McCabe

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Howard, everything in my shack is fed with my Astron 50 amp supply.

Not saying my setup is perfect but have tried to follow your quiet station guide.
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Larry - W8LLL

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I run an astron 70 linear supply and get the same results. Tonight i will supply the LP-700 with a battery and see what happens.
(Edited)
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KC2QMA_John

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Damn! I was almost certain that would work.
I don't have A LP-500 yet but it on my wish list. 
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Rich McCabe

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Well I am.
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KC2QMA_John

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Like i said a dumb question :)
(Edited)
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Rich McCabe

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Never a dumb question. I have been known to overlook the obvious :)
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Larry - W8LLL

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I ran my LP-700 off a battery, no improvement with the ripple wave form.
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KY6LA - Howard, Elmer

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Install soome ferrites on all the cables.
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Rich McCabe

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I have ferrites on everything. Most cables have at least two if not three depending on length. This includes power, USB and coax.
(Edited)
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KY6LA - Howard, Elmer

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I will be back in the United States next week. I will put on my l system then
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Larry: KE2YC

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Hi Rich,
I'm sure you have the Lp-500 grounded? Try and put a second ground wire with the first, only make it about 9-12 inches longer. So you will have 2 (two). Ground wires coming from LP-500

Larry ke2yc
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Rich McCabe

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Larry, I do. You can see the braided strap in the pictures.  I get what you are saying about the length but it looks exactly the same on every band. So I don't think its related to the length of the wire. I assume that is what you were getting at?
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Larry: KE2YC

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Rich, yes that is what I was suggesting. Changing frequency would not change the harmonic frequently the LP-500 was putting out. Adding second ground would make sure that harmonics are not causing a problem. The harmonic will not change on band change

Larry ke2yc
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Rich McCabe

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I unhooked the ground with no change and tried another wire about 18" longer. Exact same results. But worth a shot :) Also tried running a wire from the LP-500 tot he Flex and no change.

I have Julius sending me an iBox as I think the isolation of my iPlus took care of the bumps. The iBox will also give me attenuation so I can properly use the 8 pin foster connector.
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Rich McCabe

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Thanks Howard.  I talked to Julius (W2IHY) about feeding it into the back of my iPlus. He suggested I feed it into my EQplus which will go through the iPlus. The bumpiness went away but my IMD looked awful. The 3rd harmonic was less than 10db down from the fundamental.  I was able to drop the gain level down on the EQplus to help the IMD but then I could not get much drive on the radio.

So without sticking my neck out too far it appears the isolation in the iPlus helps the bumpy issue.
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Larry - W8LLL

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What was the highest output power you achieved without the bumps in the wave form?
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Rich McCabe

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Mine starts to get bumps at 1 watt.   The iBox should be here this week. Julius shipped it this morning. I think there is a good chance this will fix the issue.

Any of you LP-500/700 guys have interest in joining a group on this product?  Larry has a Yahoo Group for the LP-100 but not the 500/700.  I was thinking about starting one on Yahoo so we don't take over the forum here.  I am not a fan of Yahoo but figured we should stick to the same format as the LP-100 in case Larry decides to take ownership of it.
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Rich McCabe

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I have been trying for a couple weeks to find it so not sure what the deal is. Larry has added me now so I have access. If I log out of Yahoo and search its not there! 

As far as Yahoo being broke, I think they are broke even on a good day.

Thanks again for the link Roy.
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Roy Laufer

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You are quite welcome!
Yes, Yahoo! works in mysterious ways. They would not be the first company that wouldn't mind "killing" services that cannot be monetized well.
Larry's LP-500 group has been very useful in the past. Larry has "threatened" to offer a switching audio input box, just for this purpose after he finishes up on all those non-HF couplers that were announced for "any day now"...
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Rich McCabe

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So how long have the VHF couplers been listed as coming soon?

And it took you 3 1/2 years?  I thought my 11 1/2 months was bad since it was only supposed to be as much as 6 months. 
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Roy Laufer

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In a way, I have been waiting for those couplers since my earliest days of hearing about the planned LP-500!

Before the LP-500 was even announced I had emailed Larry to ask if there was any future where the LP-100 would be able to work with a UHF/VHF coupler. He was kind enough to explain to me that the LP-100 had inherent limitations, which would make this impossible.

When the LP-500 was just an idea in Larry's mind, I asked him whether the LP-500 would be designed with UHF/VHF sensing in mind as well as HF, and he told me that this was one of the many features he had "baked in the cake".  I put my name on the waiting list shortly thereafter, and began my great wait...

It was well worth it - I REALLY like my LP-500!

I regret that Larry has decided to keep this project totally in-house - he is so busy building and calibrating all those LP-500/700's that he is selling that he has far less time to design and test the accessories that he planned years ago...

Still, I remain optimistic and I have the shack wired up with barrel N connectors to be replaced with Larry's couplers "any day now"...

If this hobby has taught me anything, more than electronics, it is patience.
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Rich McCabe

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Roy, patience is not something I am good at.  I normally wont wait 15 minutes in a restaurant for a table. Being on the list for a LP-500 and 6600m has been a major challenge for me :)

That said, I am happy with the LP-500 and Larry is top notch for support and products.

And I agree, his desire to build in house is limiting his ability to further develop the products.
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Larry - W8LLL

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Larry - W8LLL

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(Edited)
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Rich McCabe

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Well in my case I have concluded the Flex ACC port (Pin1) is not an option if I want it to work properly. The signal out of the LP-500 will not drive it properly.  The 8 PIN foster connector is going to need attenuation and the balanced input seems about right.

Regardless of what type if input I use it is going to need some sort of line isolator. The iBox will be here in a few days so will see how it works.  The nice thing about the iBox is it also has an attenuation adjustment so I should be able to dial that in.
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Larry - W8LLL

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When i get the transformers i will experiment, i am thinking with the 600 ohm transformer in place the line in on the assy port and the processor on may give a large and clean enough signal, we will see
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Rich McCabe

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I will check it again when I get mine connected but using the processor caused me nothing but grief.

Course I tried so many setups not knowing if its was a cabling issue or operator error that everything I tested is now a blur.
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Larry - W8LLL

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OK, so I received the 600 to 600 ohm audio isolation transformers and it solved the ripple in the wave form problem. This is inputting the 2 tone test signal into the accessory  plug. I am using the processor in order to have close to 70 watts output with the 2 tone signal.


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Rich McCabe

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Larry, what does your flex level meter show?  Trying to figure out how hard you are driving the flex.  I have installed the iBox and am still getting bumps although not quite as bad. No where as good as yours.
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Larry - W8LLL

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The level meter gain is right up to  0 db without going over.  
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Rich McCabe

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Thanks Larry.  I just put a post on the Yahoo group.
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Larry - W8LLL

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Rich McCabe

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Thats good. My ibox is out for delivery today so should know if it works in a little bit.  I am going in the balanced line.

I wish Larry would build the isolation transformer into the LP unit !
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Larry - W8LLL

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I just put another isolator transformer in line with the front mic plug (foster) and it works just as good, this time turning off the processor when using the 2 tone as its not needed.

Larry talks about eventually creating an isolator transformer to use with these meters when time allows.

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Rich McCabe

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Well unfortunately as Roy mentioned Larry is so busy building production units he doesn't have time to further develop stuff.

So not going to hold my breath on an isolation transformer :)
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Mark - W6MSB

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I finally made it to the top of the list and my LP-700 order will go in tomorrow. Any update on best practices for interfacing the 2 tone generator to my 6700?

Mark
W6MSB
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Rich McCabe

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Mark, I would order a iBox from Julius and cut to the chase. For a clean two tone signal you need to isolate the LP500/700 from the Flex.  You will likely need to adjust the level as well. The iBox does both.

If that does not do it, you might have to mess with the power supply ground if you have an Astron but I think it most cases the iBox will do it.

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Chris DL5NAM

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Chris DL5NAM

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... and also

There is a tiny tool you can download  a 2 Tone Generator
It's easy to change audio source in SmartSDR

Not any ripple problems

http://dl6iak.etonlein.de/projects/2001-04-28.htm

73 Chris
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W5XZ - dan

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it's really too bad we don't have 'built in test equipment' ( BITE ) in SmartSDR like we had
 in PowerSDR...under the 'Tests' tab....two tone generator, signal generator...

nothing else was needed...and, early on, we even got a hint BITE might be available
 in SmartSDR....but, it never happened...

'just sayin...'    73, w5xz, dan