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G8MNY > TECH 27.06.24 10:31l 70 Lines 3366 Bytes #999 (0) @ EU
BID : 10435_GB7CIP
Read: GUEST
Subj: FeelTeck Dual DDS Osc FY6600-60M
Path: IW8PGT<IZ3LSV<DB0ERF<DK0WUE<PD0LPM<I0OJJ<GB7CIP
Sent: 240627/0910Z @:GB7CIP.#32.GBR.EURO #:10435 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@EU
By G8MNY (Update Jun 22)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I used one of these new osc for a ham Training course. It did loads of useful
demos except it could not do "a distored AM signal", so I could not easily show
over modulation. (swapping the sine modulation for a trapeziam waveform will
work)
<-------------------200mm----------------> Rear
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On Display Opt Osc1 Osc2 IN SyO SyI TTL USB
SPEC
Mains 2 pole figure 2, 100-260V 10W. The SMPSU gives +5 & +/-12V
Both osc DC-60MHz in mHz steps! 1uV-20Vp-p unloaded, 50R BNC
32 wave shapes are pre programmed, & 32 more Arbitrary possable
DC offsets 1mV-10V on some freq ranges
Phases can be set to 0.1 deg accuracy between osc/sync O/P
Modulation Osc2 modulates Osc1, in AM, FM, PM, ASK, FSK, PSK, Pulse, Burst
Frequency sweeps of Osc1 possable in linear & log etc.
Counter mode needs 1.5-5V input reads up to 100MHz. +/- 20ppm
Colour Display show selected menu [1-5] params & an O/P mode graphic
CALIBRATION
Frequency accuracy is poor both as a signal gen & counter, but modulation
accuracy all spot on by DDS design.
Modulations are in peak-peak value, some maths are needed for the real value.
For FM Dev enter 2x for P-P Value. For PM use Rad x2 x57ø for P-P deg to 360.
For AM modulation has been wrongly referenced from the peak value not the mean,
which gives -ve modulatiopn depth only, so 66% is actually 50% AM depth, but 0
& 100% are still OK. At 200% you get double side band no carrier, a useful 2
tone test signal!
IN USE
Not so easy to set up, as 8 digit used for most params. Pressing "Adj knob in"
give range scale change (Hz kHz MHz etc). Changing the frequency manually gives
noisy results, as the CPU commands to the DDS upset the output. And like all
computer controlled signal sources there is some low level VHF RFI from the CPU
visable on a good spectrum analyser, and you can also see the varous DDS system
mirror images as your change RF freq etc.
The 2 locked phase & level adjustable sources are a good way of testing "noise
null steerer canceller" devices.
RFI
Inside there is a tiny SMPSU with just fuse & small a balanced choke before the
bridge rectifier & 10uF 350V of DC smoothing. I put in another balanced choke &
a u1 (from a scrap SMPSU) soldered to the mains socket to give better than 20dB
further unwanted SMPSU QRM supression.
See my tech Buls on "Syston Donner 115 Pulse Gen", "198kHz Off Air Standard",
"Comparing Off Air Freq Standards", "Off Air Lock for Ref Osc"."Scope RF Trick"
& "Marconi 2019A Sig Gen".
Why don't U send an interesting bul?
73 de John, G8MNY @ GB7CIP
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