Od: Vladimir.Petrzilka [ok1vpz@seznam.cz]
Odesláno: 10. ríjna 2001 21:13
Komu: jan.urbig
Predmet: DF0MTL interference

Dear Jan

During UHF contest more czech stations had on 1296 MHz heavy interference from your contest station. It was not any splutters, but just "broadband noise". In our QTH it was appear as unmodulated noise across whole 23 cm band in level up to S5, when our dish was directed anywhere outside to you.
This noise was occured immediately, when your transmitter was switch, even if your sinal was not modulated. So under my suspection it look as badly designed transmitter way, where is too high gain, probably limited only by ALC, or by similar regulation. We already have similar experience with new TS 2000 from Kenwood, where transmitting route is not designed very well from this point of view.
Please check this problem, test your equipment again in real conditions and fix it, to prevent any future disturbance between contesters.

Thank you for understanding
(OK2KKW Contest club)

Od: Jan Urbig
Odesláno: 11. ríjna 2001
Komu: ok1vpz@seznam.cz
Predmet: Re: DF0MTL interference

dear Vladimir,
at first congrats to your excellent results in october contest. I apologize for
any problems you have had with our signal on 23cm's. I forwarded your mail to our
23cm-OP but have no answer at the moment.
He said that no one complained about our signals during the contest so he didn't 
know about signal problems. To me it seems that the problem was that our power
supply line is very lossy (700mtrs up the hill) and so there was low voltage in our 
QTH (we had several problems with power supplies that didn't work
properly).Our Equipment is a FT1000MP with DB6NT tvtr directly form 28 to 1296MHz 
and then a PA with 8 times the motorola modules. I know these are not the best
choice in case of intermodulation but we checked the spectrum at home an it was within
the limits. So actually I can't say more than sorry and wait for the
results of discussions between us und results of equipment test.
Thank you for your patience,
73's de Jan, dl3jan
PS:we used your vusc-program for the first time on both 70,23 and microwave. I think
the network function is very useful, but from our point there are 2 weak points: 
no 9cm included and you have to log a qso if you want to have the direction in 
degrees for a specific locator.
From: tilo.arnhold
Sent: Friday, October 12, 2001 
To: ok1vpz@seznam.cz
Subject: VY SRI fer qrm 
Dear Vladimir,
we are very sri that you had problems with our signal on 23cm. Jan has send your 
email to me because I have built up the 23cm-equipment.
During the contest (when I was on 23cm) only one station told us about problems with 
our signal. It was OK1KZE in JN79FX. We switched the antenna (from the yagi-group 
east) to the quad-group (west)) and he says, it´s better. So we believed, the problem 
is, that his RX cannot good handle with strong singnal. 
After your email I know, the problem must be in my TRX-configuration. We used FT1000MP 
(IF 10m) > DB6NT-TVTR > Filter > 1x M57762-module > 8x M57762 modules by DL2AM > ANT. 
One of the 8 modules didn´t gave power-output. That was the result of some measuring - 
sessions 2 days before the contest. We had not the time to change this module, so we 
decide to isolate it by 50 Ohm and to work with 80W and not with 100W. I have spend 
some days and a lot of hours to find the reason for the "low" output. And of course 
we had the PA-output on the analyser for checking the signal (2 days before the contest). 
On the analyser the signal seemed to be ok and we decide to use the pa in the contest. 
(Maybe the signal-quality of the M57762-modules is not good enough for contests in 
areas with many stations on small distances ?) I don´t know the exactly reason for 
this noisefloor-problem at the moment, but I will change 1 of the 8 module during 
the wintertime. And after that I will check the signal by the analyser again to find 
the reson. Ok ?
So, pse don´t worry. In the next year this problem will not be anymore.
Again: we are vy sri for the problems in this contest.
All the best ! GL in contest es best DX !
vy 73 de Tilo, DH1FM (23cm-Op at DF0MTL / JO60LK)
PS. Just 2 questions: Were there differences between cw and ssb or was the 
noisefloor in ssb and cw ? You wrote more czech station had problems. Thats 
not vy exact. Who are the stations, I should say sri ?
From: "Steffen Koehler" 
To: <ok1dfc@tesmail.cz>;
Sent: Monday, October 15, 2001
Subject: TS870 Noise
Hi Zdenek,
tnx for your TS870 noise report. We know about the problem of wide band noise, 
but we think it is not that easy to overcome with a simple solution. Problem 
with noise is evidently thanks to TS870 because this TRX has wide band oscillator 
and only DSP selectivity. Thanks to switching LO (each 100kHz) in FT1000 we do not 
have problem between station in OK and stations witch are very closer. But problem 
is, when TRX TS870 produce wide noise in LO, this effect must be on RX and TX some.

Allthough you might think that the TS870 TX/RX concept does not perform well 
compared to the FT1000MP, it is somehow different to your description.
The Problem is in fact the noise from the VFO for converting the 8.83 MHz last 
IF to the final frequency, which is - as in the FT1000MP - a hybrid solution of a 
switched PLL combined with a DDS circuit. The LO's are also implemented variable, 
but there is additional selectivity by crystal/ceramic filters on 8.83 MHz and 
455 KHz IF respectively, not only DSP selectivity.
Since you can hardly (and would also probably not plan to) implement an additional 
tunable narrow filter in the 28 MHz range, reducing phase noise of the VFO is the 
only way with significant influence on wide band interference. Producing an excellent 
phase noise of -148 dBc is simply  not reachable for us, we are unfortunately unable 
to measure it too. The TS870 has a carrier subpression of approx. 80 dB, but at 
-148 dBc noise is again more than 60 dB below, which can't be measured with our best 
spectrum analyzer. We can potentially reach about -120 dBc, that seems to be generally
Also, the noise problem of small signal bipolar transistor stages seems to appear 
significantly in the TX path of the transceiver and the transverter. For as low 
noise levels as -148 dBc, we would have to set up a pure MOS design, which is far 
beyond our budget.
If you have found any good solution for VFO/DDS improvements that might be adaptable 
to the TS870 - please let me know.
Steve, DH1DM - contest crew DF0MTL -
Od: Vladimir Petrzilka [ok1vpz@seznam.cz]
Odesláno: 22. ríjna 2001 3:41
Komu: tilo.arnhold
Predmet: RE: VY SRI fer qrm 
Dear all
Just I got copy of e-mail (in annex) from Zdenek OK1DFC, which created some suspection
about observed noise floor discused few weeks ago. Really on your side FT 1000 Mp was 
used for 23 cm and not TS870 ? TS 870 is very well known as bad designed TRX, produce 
too much noise - it is not matter of sideband noise of local oscillator (but as well), 
but rather as bad designed TX chain, where very low signal after pass through filter 
and mixer filter is amplificated. And of course first stage has quite high broadband 
noise, which probably generate a noise floor, indicated by us on the band. This nose 
floor is of course  irrelevant on HF(because of dynamic), but very substantial on VHF/UHF. 
From that perspective, just superior HF transceivers are usable on VHF/UHF bands.
Just very short calculation:
You were 9 km from us - let's say 10 km
Your had aprox.100 W
You had let's say 20 dB antenna gain
How strong signal was at our receiver?
Let us use simple (but quite precise) attenuation formula:
      Au = 20 × ( - 4.622  -  log f  - log L)
f is frequency in GHz
L distance in km
    for our example it is:  Au = 20. ( -4.622 – 0.11 – 1)) =  -114 dB
    Radiated power: 100 x 100 = 10 000 W ERP =  40 dBW = + 70 dBm
In case, that we were not turned to you our antenna had let's say 0 dB gain.
From that we can calculated approximate PWR on our receiver input:
  70  - 114 =  - 44 dBm 
For VHF / UHF transceivers S9 level is defined as - 93 dBm. So in that case, 
your sigs were 50 dB above S9. (In case of OK1KZE observation, when they were 
100 km away, it was almost exactly the same level, but, of course, if both of 
your both 20 db antennas were directed to each other).
If your broaband noise was (generated by TS 870 ?) let's say on the same level 
as sideband noise of L.O. at 20 kHz distance (TS 870 has as measured approx. 
-120 dBc/Hz), we received this noise through 2.7 kHz wide SSB filter as 
2.7 x 1000 more intensive so 34 dB stronger =>  -120 + 34 = 86 dB bellow carrer, 
so bellow S9 + 50 dB => it is approximately at 36 dB bellow S9 => S3 !!!  
It is very close to our observation.
Conclusion: to prevent interference, your spectral purity should be minimaly 
20 dB better, then it was. It mean FT 1000 as low level sideband noise generator 
is principal condition, but as low as possible gain after FT 1000 transvertor 
output is necessary as well.. Transvertor output of FT 1000 MP has approx. 
- 6dBm, and so up to 100 W PWR you don't need more, than 60 dB overall gain 
from - 6 to + 50 dBm) with some 4 dB reserve for interconnection and regulation. 
I believe, that if you will use that configuration, no problems will appear in 
practical operation any more .
So my suspection is that : either not FT 1000 MP, but TS 870 was used for 23 cm 
on your side, or much higher gain was adjusted in the 23 cm TX chain (in case of 
disconnected ALC loop, if used).
No differency in noise floor were observed in case of CW or SSB operation - just 
noise, which had not change in relation of your modulation - so it take us to evidence, 
that not phase sideband noise, but noise of bad designed TX chain was observed. 
But of course, even if it is unprobable, maybe DDS synthesizer of TS 870 could 
produce broadband noise as well, who knows...
Measurment of broadband noise is not problem, but it is not task for spectrum 
analyzer, because analyzer has ever much worse sideband noise compare to any 
transceiver. For test kindly use dummy load, from which sample of RF signal is 
going through very sharp rejection filter (help to attenuate carrier) into measurment 
receiver without AGC and with excelent local oscillator spectral purity. We use for 
those tests another transceiver with very good stopband (two crystal filters on 
different IF's), crystal as receiver local oscillator and blocked AGC. On the AF 
output of receiver is for observation connected AF milivoltmeter with dB scale. 
For calibration of this measurment system simple noise generator with known 
output level is used.
I hope, that those ideas could help you to prevent similar problems within next contest.
Best regards
OK2KKW team
Od:  Steffen Koehler
Odesláno: 22. ríjna 2001 
Komu: ok1vpz@seznam.cz; 
Predmet: TX noise
Hi Vladimir,
thank you for your interesting e-mail. Yes, we know about RF wave distance 
attentuation difference between SW and VHF/UHF/SHF and yes, it is true that 
3...6 dB performance
improvements are not enough. Of cause, we can distinguish between a TS870S and 
a FT1000MP, they even look different :-).
The reason for our FT1000MP driven "bad signal" on 23cm can be easely seen 
below. As you will point out, the FT1000MP has far not 20dB better TX noise 
than other transceivers. But ok, the FT1000MP's RX dynamic range is significantly 
vy 73's de Steve, DH1DM
The March 2000 issue of RadCom has an in depth technical review of the new 
ICOM  IC756 PRO.  I have summarized three key technical measurements on a 
variety of transceivers, all made by the same reviewer, Peter Hart, using the 
same methodology.    The three measurements are the two-tone dynamic range 
(in a SSB bandwidth), a reciprocal mixing measure, and the amount of transmitter 
broadband noise (also in a SSB bandwidth).   The rigs are listed with the best 
at the top in terms of close-in performance. The IC756 PRO ranks near the bottom.
Spacing         3k      5k      10k     15k     20k     30k  
Corsair I - November 1984 - no synthesizers 
DR               -      90      90      90      90      90
Recip            -      98      98      98      98      98
TX noise        95      95      95      95      95      95  
OMNI-VI - January 1994 
DR              88      88      88      88      88      88
Recip           86      86      -       96      96      96
TX noise        83      87      96      97      98      98
FT1000MP - January 1996
DR              78      82      92     103      99      98
Recip           80      86      94      99     103     108
TX noise        76      81      89      94      96      99
IC737 - September 1993
DR              74      80      88      92      94      98
Recip           90      96     104     105     107     110
TX noise        79      87      93      95      96      97
FT990 - April 1992
DR              70      78      88      92      94      96
Recip           83      87      93      97     100     105
TX noise        74      79      84      86      87      88
TS690S - November 1992
DR              67      77      87      91      93      94
Recip           -       -       -       98     101     105
TX noise        70      77      82      85      88      88
TS930 - May 1986
DR              -       77      87      -       91      92
Recip           77      83      89      -       97     101
TX noise        -       79      83      -       85      88
TS940 (with Lowe modification to improve reciprocal mixing by 12db)
        - May 1986
DR              -       76      81      -       88      91
Recip           83      89      98      -      105     110
TX noise        -       72      72      -       72      74
TS850 - October 1991
DR              -       75      89      95      95      96
Recip           85      89     100     105     108     112
TX noise        75      83      90      95      96      99
IC756 - May 1997
DR              74      74      75      79      82      86
Recip           79      84      91      95      98     102
TX noise        73      80      87      91      94      97
IC756 PRO - March 2000
DR              72      73      76      82      86      90
Recip           83      86      92      96      98     101
TX noise        -       -       -       -       -       -       
IC775DSP - January 1996
DR              72      72      78      87      91      93
Recip           90      96     100     103     106     109
TX noise        78      80      87      92      97     100
FT920 - August 1997
DR              70      72      83      95      97      96
Recip           85      90      97     101     104     108
TX noise        -       -       -       -       -       -
TS50S - May 1993
DR              67      69      74      80      84      92
Recip           78      84      95      -      103     104
TX noise        74      79      85      90      93      97
FT847 - August 1998
DR              65      67      78      89      96      94
Recip           76      80      90      94      97     101
TX noise        70      76      86      90      93      97
FT1000 - June 1991
DR              65      65      72      82      88      93
Recip           81      85      91      95      98     102
TX noise        -       76      81      -       84      -
TS870 - April 1996
DR              58      61      73      84      94      95
Recip           -       -       -      100     103     107
TX noise        75      80      88      91      92      93
IC781 - July 1990
DR              52      57      76      92      97      -
Recip           90      96     103     106     110     113
TX noise        -       85      92      -       98      -
DR      - two-tone dynamic range on 7 MHz in SSB bandwidth
Recip   - reciprocal mixing for 3dB increase in receiver noise
TX noise- dBC in 2.5kHz bandwidth
spacings refers to spacing of the two tones for dynamic range and
the offset from the carrier frequency for reciprocal mixing and
TX noise
Dates refer to issues of RadCom containing the Peter Hart review.
Rigs listed in order of decreasing dynamic range with 5 kHz spacing.

CQ-Contest on WWW:        http://www.contesting.com/_cq-contest/


Od: Fred Siegmund 
Odesláno: 22. ríjna 2001 
Komu: ok1vpz
Predmet: Re: VY SRI fer qrm 
just to clear up the things a bit, a few words:
The noise problem of 23cm and 2m has got nothing to do with each other. 
We are using a TS870 + transverter(10m IF) on 2m and FT1000MP with
transverter (10m IF) on 23cm. The problem of 2m was discussed by DH1DM 
sufficently. I dont think that a -148dBc LO in the transverter solves 
the problem(the following stages produce a higher
noise for the total), as well as we can not afford to buy a FT1000MP for 
every band. Additionally i can say that also the phase noise of same SW
Transceivers differs especially under TS850 TRX's(we used one before on 2) 
there are significant differences. We have to think about a solution.
On 23cm we had a fault in the TX chain, which has to be found yet. But we 
saw the noise floor already on the analyzer, i hope we can solve this 
problem easier.
73 Fred DH5FS