All
these opinions are mine and mine only
and
they not represent our company official
opinion!
Update
06.02
Video
Clip added to videoclips page.
Introducting
DSP features in HF monitoring.
It can
be found here!
I
have collect little info about
Yaesu
VR-5000 receiver here.
First
couple basic fact's:
US
model is _not_ possible to unblock as many people have think with their
discussions in NG and mailing list.
Eu model is either
full coverage or just ham band receiver only, ham band receiver can be
unblocked easily with instructions what can be found here.
(work in 04 series VR-5000)
<imho>
Receiver is constructed
with quite intuitive way (good work yaesu!).
RF board is like school
exsample, "how to do good front end"
only thing what i
think is negative is PL-259 antenna connector and that antenna switching
system what switch between A and B antenna is not good as other parts on
RF board (those may effect radios performance some case's but effect isnt
big anyway.
those things are mostly
poor mechanical cortruction than poor RF performance.
Overall cheapest parts
in radio are case and mechanical costruction, RF performance
is good over all and in price range what that receiver presents its very
good or should i say exellent!
only
complain is concerning VHF air band what suffer WFM broadcast inference
in harsh Rf enviroment.
One thing what i do
like in VR-5000 is that RF-tune what actually work well and is very intuitive
idea.
Its giving possiblity
to adjust radio to your local RF enviroment.
</imho>
RF tune is constructed
in front-end filters with capacitance diodes and its have effect in bands
1.8MHz to 1240MHz (as i read from schematic diagram)
That RF-tune is frond
end bandpass filters tunign. (nice!)
Most important feature
is: they are user tuneable!!
Radio does have owen
separate front-end amplifier all 9 first band's what covers 100KHz to 1000MHz,
over 1000MHz there is uPC2711T amplifier IC what is as front-end amplifier.
All front-end switching
is made with takamisawa's G6Y-1 relays
Attenuator is made
with relay and its _first_ element from antenna, what is good indeed!.
After that relay switching
matrix there is PIN-diode switched bandpass filters.
there is totally 11
band pass filters in front-end.
T marked filter
sections mean "Tuneable"
B labeled filter sections
are fixed ones.
All front-end discrete
amplifier sectios are made with dual gate MOSFET's what give good IMD value's
and small distorsion in wide dynamic range, nice!
Update
24.02
I did
find out "how to" calibrate my VR-5000 what did have bit misscalibrated
(tansportion damage)
(that
calibration is not easy job, so its not DIY!)
after
tunign, radio is better than before, also this tuning did have positive
effect to SSB reception what is problem is 02 series units.
03 and
04 series units dont suffer that SSB distorsion problem as earlier japanese
versions (02) does have.
also
in 03/04 series circuitboards are LOT4 generation, not like 02 have LOT3
generation.
also
in 04 series have other firmware, software version is 1.12 and other radios
have 1.07 version
Also
VFH airband reception become better after i did calibrate my unit carefully.
=)
I did
also receive repair instruction from Vertex/Standart conserning 02 series
SSB reception distorsion problem, after that mod, SSB reception is far
better than originally.
but
radio is really accurate what comes to calibration.
100Hz
frequency error in LO oscillator does quite big difference in SSB reception
performance.
Update
28.02
Rich
Wells have publish his review of VR-5000.
It is
that same japanese model what is in my monitoring corner, its 02 version.
Review
can be found here:
http://www.strongsignals.net/
Tech
spec's
Reception range 100KHz-2600MHz
Main receiver
IF's are:
1st. 614MHz
LC filtering
2nd. 45.775MHz
Crystal filtering
3rd. 10.7MHz (IF output
is taken from here and WFM mode last IF)
Filtering is ceramic and Crystal!
4rd. 455KHz Ceramic
filters (3 different band width)
Sub receiver
IF's are:
1st. 614MHz (common
with main receiver)
2nd. 80.1MHz LC filters
3rd. 45.05MHz crystal
filters
4rd. 455KHz ceramic
filters (3 different band width)
Subreceiver also does
handle bandscope.
IF output:
IF output is taken
same place as WFM mode circuitry, its passed thru 3 IF stages and filters,
output bandwidth is +/- 100KHz (-3db width)
In 10.7MHz frequency
range
Record output:
Act like discriminator
output, taken before volume controll, squelsh circuitry but have DC filtered
so flex protocol and other fast data transmissions are not allways proberly
available.
Front end:
VR-5000 use relays
in front end connection, first thing in signal line in ATTENUATOR relay!
(good!) and after that there are switching relaynetwork and PIN diodes
what does connecting to bandpass filtering
Basicly front end is
first divided 4 ways with relays,
100KHz-622MHz in own
way (A),
(also A-B antennas
are available in that area)
Second part is 622-1240MHz
(B)
Third part is 1240-1850MHz
(C)
Fourth part is 1850-2600MHz
(D)
Bands 100KHZ-30MHz
have their own RF amplifier circuit.
(3SK228 dualgate mosfet)
30-90MHz have their
own RF amplifier (again dualgate mosfet)
90-313MHz have their
own RF amplifier (again dualgate mosfet)
313-622MHz have their
own RF amplifier (again dualgate mosfet)
622-1000MHz (tuneable
filtering)
have their own RF
amplifier (again dualgate mosfet)
622-1240MHz have their
own RF amplifier (again dualgate mosfet)
1240-1850 RF amplifier
is uPC2711T IC amplifier
1850-2600 RF amplifier
is also that uPC2711T IC amplifier circuit.
First mixer is common
in bands (A) 100KHz-622MHz (dualgate mosfet)
B, C, D bands use
as well own first mixer circuits.
Front
end filters band widths are:
T marked filter
sections mean "Tuneable" (RF-tune function)
B labeled filter sections
are fixed ones.
Bands below 622MHz
are in own part of front end switching relay network and 622MHz - 1240MHz
is own separate section
As well 1240MHz -
1850MHz and 1850MHz - 2600MHz.
100KHz - 1.8MHz
(B)
100KHz - 622MHz (B)
???? dont know why this is there
1.8MHz - 4MHz
(T)
4MHz - 12MHz
(T)
12MHz - 30MHz
(T)
30MHz - 90MHz (T)
90MHz - 313MHz (T)
313MHz - 622MHz (T)
622MHz - 1000MHz (T)
622MHz - 1240MHz (B)
??? dont know why this is there
1240MHz - 1850MHz
(B)
1850MHz - 2600MHz
(B) high pass filter
23.04-2001
I just stopped playing with my VR-5000 and result
was this:
