Voodoo-LABS TS-950sdx Receiver ESSB Mod Comparison Graphs

TS-950sdx Comparison Graphs

Gotta See dat VOOODOOOO!!!

Well, You saw how Horrid the Graphs
were on the stock TS-950sdx for Audio Fidelity.
You should of HEARD it!! Auuuug!!
Big disappointment, but not unexpected.
The TS-850s was in the same situation before it was modded.
No big thing.

Here you'll see some comparison graphs
of the Stock SDX compared to the Fully Modded SDX.
There's a tremendous improvement.
Read On!
(SpectraLab software was used for all Graphs)

Modded SSB

Main Receiver:

Whitenoise - Headphone/Ext Speaker Jacks
The Frequency Response of SSB on the Main Receiver was improved dramatically after all the mods were accomplished.
The Low Frequency rolloff was extended to 25cps and the Highs to 3Kc.
The average -3db bandwidth was improved considerably from 20cps to 4.5Kc.
This was measured with received whitenoise.
When measured with a Carrier Sweep (see below) the -3db bandwidth is from 10cps to 6Kc.

Click on the Graph to make it Bigger.

Carrier Sweep:
This is a SpectraLab Graph of a Carrier Sweep accomplished on LSB.
The Lows start rolling of at around 30cps and the Highs around 5.5Kc.
The average -3db bandwidth is from around 10cps to 6Kc.

TX Monitor:
This has improved phenomenally.
Now that the bandwidth of the AF circuits are better, the Monitor actually has some fidelity.
We still have some issues with it though.
We have always had some High Frequency distortion on both the Sub-Receiver and Monitor voice peaks.
Also there's an audible low level 2kc and a 4kc tone on the monitor audio.
These anomalies were there even before the mods were accomplished.
This Spectra Graph is of the TS-950sdx Monitor with a Frequency Sweep Xmitted thru it.
There is also a line for the TS-850s/DSP-100 that received that xmission.

Modded AM

Whitenoise - Headphone/Ext Speaker Jacks
The Frequency Response of AM was improved a hell of a lot.
The Lows start rolling of at around 30cps and the Highs around 2.3Kc.
The average -3db bandwidth is from around 20cps to 4Kc.
We've tried to extend the High Frequency Response more than it is.
It isn't being limited by the AF circuitry any longer (it passes frequencies flat from 20cps to 10Kc now), nor is it the IF filters.
We have bypassed all the IF Filters to be sure that wasn't it.
We also know it isn't the AM Detector, 3 different detector circuits have been tried, including a Full Wave Detector...No Go.
We think we have it narrowed down to 2 things.
Its either the 1st IF, 73.05Mc 15Kc Roofing Filter which will only allow 7.5Kc of AM Sideband information thru,
Or the IF VBT/Slope Tune Circuitry that adjusts the IF Mixing Frequencies to shift in the IF Filters.
It could also be a combination of both of them.
We'll keep workin on it, as this will also affect the ultimate bandwidth that will be received in SSB.

That's It!!!

Well, As ya'll can see, there's a remarkable improvement!
There are a few bugs that need to be worked out here and there,
but for the most part it is looking perty good.
Actually listening to Hi-Fi stations on the air is Audio Bliss!
It is very comparable to my TS-850s/DSP-100 Combo.
In fact, We think there might be a little
more body and fullness to the sound.
We'll be making some comparison recordings of
the two rigs in the near future for ya'lls Pleasure.
They'll be posted right here when We get em done.