"TraceMyIP.org"
27.12.19
25.11.19
RF Radiation public mesures system Η ακτινοβολία Ραδιοσυχνοτητας στην Ελλάδα
Site with public announcement about RF radiation measures in Greece ( by map )
Only Greek
Η Ε.Ε.Α.Ε. είναι η αρμοδια Εθνική Επιτροπή Ατομικής Ενέργειας .
Στην ιστοσελιδα παρακάτω μπορειτε να διαβασετε πόση ακτινοβολια Ραδιοσυχνοτητας υπάρχει συμφωνα με πρόσφατες μετρήσεις στην Γειτονιά σας και τα ορια ασφαλείας .
Στην ιστοσελιδα αυτη, μπορειτε να διαβασετε τι ακτινοβολία υπάρχει απο όλα τα Ραδιο-δικτυα .
Ομως να ξερετε οτι την περισσότερη την δέχεστε απο τις συσκευες του σπιττιου σας αναλογα με την αποσταση και τις ωρες εκπομπης αυτων.
Κυριως από το κινητο τηλέφωνό σας , αν μιλάτε πολύ καθημερινα {πολυ = > 10 -15 λεπτων συνολικα ημερησιως κατα !!? προσεγγιση??? ) και τις συσκευες wifi ) .
Και μια διευκρύνιση ακόμα: η ακτινοβολια Ραδιοσυχνοτητας δεν ειναι ιονίζουσα ακτινοβολια π.χ. όπως είναι η Ραδιενεργεια .
Απο αλλες περιοχες αλλαξτε θεση στον χαρτη. Αυτα τα αναφέρω προς τους FB φίλους δυνάμει σχετικου πτυχιου στο επιστημονικό αντικειμενο .
Προσεχετε λοιπον το κινητο σας τηλ. περισσότερο απο τις άλλες κεραιες.
Σας ευχαριστω πολύ.
πατήστε ΕΔΩ
Only Greek
Η Ε.Ε.Α.Ε. είναι η αρμοδια Εθνική Επιτροπή Ατομικής Ενέργειας .
Στην ιστοσελιδα παρακάτω μπορειτε να διαβασετε πόση ακτινοβολια Ραδιοσυχνοτητας υπάρχει συμφωνα με πρόσφατες μετρήσεις στην Γειτονιά σας και τα ορια ασφαλείας .
Στην ιστοσελιδα αυτη, μπορειτε να διαβασετε τι ακτινοβολία υπάρχει απο όλα τα Ραδιο-δικτυα .
Ομως να ξερετε οτι την περισσότερη την δέχεστε απο τις συσκευες του σπιττιου σας αναλογα με την αποσταση και τις ωρες εκπομπης αυτων.
Κυριως από το κινητο τηλέφωνό σας , αν μιλάτε πολύ καθημερινα {πολυ = > 10 -15 λεπτων συνολικα ημερησιως κατα !!? προσεγγιση??? ) και τις συσκευες wifi ) .
Και μια διευκρύνιση ακόμα: η ακτινοβολια Ραδιοσυχνοτητας δεν ειναι ιονίζουσα ακτινοβολια π.χ. όπως είναι η Ραδιενεργεια .
Απο αλλες περιοχες αλλαξτε θεση στον χαρτη. Αυτα τα αναφέρω προς τους FB φίλους δυνάμει σχετικου πτυχιου στο επιστημονικό αντικειμενο .
Προσεχετε λοιπον το κινητο σας τηλ. περισσότερο απο τις άλλες κεραιες.
Σας ευχαριστω πολύ.
πατήστε ΕΔΩ
SDR Servers IN GREECE and more
GLOBAL
SDR SERVERS FROM GREECE AND MORE
AGRINIO
Makri Evros THRACE Greece
Alexandria Imanthia Greece
Eginio Katerini Greece
Rodos Island Greece
Athenns Greece
κρητη
HLEIA
http://222kiato.ddns.net:8073/
EUROPE
LZ7AA
Germany Friedrichshafen
Chelyabinsk
N America
Utah USA CW
GEORGETOWN EC
ORLANDO FL
K3FEF
Open new tab and type chrome://settings/content/sound
then add this site to the allowed list"
26.9.19
QRO QUESTION
under construction ..............
bilingual lower in Greek
Today two reference values exist: for frequencies below 30 MHz, S9 is defined as a voltage of 50 μV over 50 Ω at the receiver antenna connector; for frequencies above 30 MHz, S9 is defined as a voltage of 5 μV over 50 Ω at the receiver antenna connector. This refers to an unmodulated carrier signal that uses almost no bandwidth; in case of real signals using a given bandwidth, this definition may not be enough since a smaller receiver bandwidth allows a weaker minimum detectable signal, but S-points are still a good tool for comparing received signals.
Older receivers were calibrated using the old standard that defined S9 as a voltage of 100 μV instead of 50 μV over 50 Ω at the receiver antenna connector
It is difficult for a person, especially most new hams these days, to fully appreciate the decibel. Wattmeters make it easy to see a large change in output power by watching the needle move its entire distance but this change doesn't really mean much when you think about what amplification really is. For a person to increase their output power level by 3dB, you must double your power output. For 9dB gain you must multiply your current power output by 8. For SSB operation you need approximately 10dB gain (precisely 1.67 S-units, 10x your output power) to make a clearly noticeable improvement to the person listening on the other side. So what does this mean in plain English?
For hams saying QRP is a waste of time, a 5 watt radio is only about 2 S units below someone running around 100 watts:
I did not mention above, but no radio will show a linear S-unit gain for each 5dB of signal. Search hard enough and you will find that various brands of radios will need only 2dB for the first 3 S-units, 5dB for the next 4 and so on - others have a completely diferent pattern. You have to use your own judgement and base RST how much stronger the remote station is above the noise floor.
If you want to know if your amp is splattering, use what I call the "Wave Meter" - wave at your neighbors; if they wave back you're okay
ΑΚΟΥΩ ΣΕ ΕΛΛΗΝΙΚΑ ΠΗΓΑΔΑΚΙΑ ΠΟΛΛΟΥΣ ΕΛΛΗΝΕΣ ΡΑΔ/ΝΕΣ ΝΑ ΧΡΗΣΙΜΟΠΟΙΟΥΝ ΤΕΡΑΣΤΙΕΣ ΙΣΧΕΙΣ (> 500 ) ΓΙΑ ΕΠΑΦΕΣ ΕΝΤΟΣ ΕΛΛΑΔΟΣ !!!
Το πρώτο ερωτημα που μου ερχεται στο μυαλο ειναι : 1. Γιατι οι εταιρίες φτιαχνουν πολυ ακριβα μηχανηματα που εκπεμπουν με 100 watt μονο?
Πολλα μηχανηματα με ισχή 100 watt κοστιζουν 10.000 Ευρώ
Βεβαιως μια απο τις απαντησεις ειναι η εξής: Για να σου πουλήσουν και εναν ακριβο ενισχυτη.
Αλλη μια μοδα ειναι το εγω το εχω ποιο μεγαλο ?
Απο τοτε που βγηκαν οι λάσπες τα αγορακια εχουν αυτο το κομπλεξ.
Το : Ποιος ειναι ο καλύτερος ειναι κατι που τυραναει τους ανδρες απο το DNA τους.
Και βεβαια ειναι στο DNA των ανδρών αυτο, γιατι υπερισχύει ο νόμος του Δαρβίνου .
Το καλυτερο DNA θα επιβιώσει.
Ετσι λοιπον ξεκιναει μια ιστορια 10.000 ετων που δεν ειναι Ραδιοερασιτεχνική αλλά Ανδρική θα μπορουσα να πω hi.
Κι ομως κι εγω θα παω διακοπες το καλοκαιρι με autostop κι εσυ με την Rolls . και ειναι το ιδιο πιθανον να περασω καλυτερα με το κοριτσι μου απο ότι εσυ με την γρια σου στην Rolls hi .
Ομως καλο θα ηταν να σταματησω το προκλητικο γραψιμο και να μπω στην ουσία του θέματος μου.
| under construction |
YAESU FL 2100B
some read about 1200 input and think they will have 1KW out..
No
550w out is good for this linear on 1200 input. Max and ideal would be 600w and don't expect more. But take care, do not exceed 100w input peaks ! Οtherwise will damage some components and eventually the valves . Don't forget you have 2400 volts there ! it's the top for 572Bs !! good dx and before all these, take serius care on your antenna efficiency.
bilingual lower in Greek
Today two reference values exist: for frequencies below 30 MHz, S9 is defined as a voltage of 50 μV over 50 Ω at the receiver antenna connector; for frequencies above 30 MHz, S9 is defined as a voltage of 5 μV over 50 Ω at the receiver antenna connector. This refers to an unmodulated carrier signal that uses almost no bandwidth; in case of real signals using a given bandwidth, this definition may not be enough since a smaller receiver bandwidth allows a weaker minimum detectable signal, but S-points are still a good tool for comparing received signals.
S-points for frequencies below 30 MHz:
| Signal strength |
Relative intensity |
Received voltage |
Received power (Zc = 50 Ω) |
||
| S1 | –48 dB | 0.20 μV | –14 dBμV | 790 aW | –121 dBm |
| S2 | –42 dB | 0.40 μV | –8 dBμV | 3.2 fW | –115 dBm |
| S3 | –36 dB | 0.79 μV | –2 dBμV | 13 fW | –109 dBm |
| S4 | –30 dB | 1.6 μV | 4 dBμV | 50 fW | –103 dBm |
| S5 | –24 dB | 3.2 μV | 10 dBμV | 200 fW | –97 dBm |
| S6 | –18 dB | 6.3 μV | 16 dBμV | 790 fW | –91 dBm |
| S7 | –12 dB | 13 μV | 22 dBμV | 3.2 pW | –85 dBm |
| S8 | –6 dB | 25 μV | 28 dBμV | 13 pW | –79 dBm |
| S9 | 0 dB | 50 μV | 34 dBμV | 50 pW | –73 dBm |
| S9+10 | 10 dB | 160 μV | 44 dBμV | 500 pW | –63 dBm |
| S9+20 | 20 dB | 500 μV | 54 dBμV | 5.0 nW | –53 dBm |
| S9+30 | 30 dB | 1.6 mV | 64 dBμV | 50 nW | –43 dBm |
| S9+40 | 40 dB | 5.0 mV | 74 dBμV | 500 nW | –33 dBm |
| S9+50 | 50 dB | 16 mV | 84 dBμV | 5.0 μW | –23 dBm |
| S9+60 | 60 dB | 50 mV | 94 dBμV | 50 μW | –13 dBm |
S-points for frequencies above 30 MHz:
| Signal strength |
Relative intensity |
Received voltage |
Received power (Zc = 50 Ω) |
||
| S1 | –48 dB | 20 nV | –34 dBμV | 7.9 aW | –141 dBm |
| S2 | –42 dB | 40 nV | –28 dBμV | 32 aW | –135 dBm |
| S3 | –36 dB | 79 nV | –22 dBμV | 130 aW | –129 dBm |
| S4 | –30 dB | 160 nV | –16 dBμV | 500 aW | –123 dBm |
| S5 | –24 dB | 320 nV | –10 dBμV | 2.0 fW | –117 dBm |
| S6 | –18 dB | 630 nV | –4 dBμV | 7.9 fW | –111 dBm |
| S7 | –12 dB | 1.3 μV | 2 dBμV | 32 fW | –105 dBm |
| S8 | –6 dB | 2.5 μV | 8 dBμV | 130 fW | –99 dBm |
| S9 | 0 dB | 5.0 μV | 14 dBμV | 500 fW | –93 dBm |
| S9+10 | 10 dB | 16 μV | 24 dBμV | 5.0 pW | –83 dBm |
| S9+20 | 20 dB | 50 μV | 34 dBμV | 50 pW | –73 dBm |
| S9+30 | 30 dB | 160 μV | 44 dBμV | 500 pW | –63 dBm |
| S9+40 | 40 dB | 500 μV | 54 dBμV | 5.0 nW | –53 dBm |
| S9+50 | 50 dB | 1.6 mV | 64 dBμV | 50 nW | –43 dBm |
| S9+60 | 60 dB | 5.0 mV | 74 dBμV | 500 nW | –33 dBm |
Older receivers were calibrated using the old standard that defined S9 as a voltage of 100 μV instead of 50 μV over 50 Ω at the receiver antenna connector
QRP and QRO can get along
QRP and QRO can get along - meaning, you can have both and have twice the fun. But having a really nice antenna makes a far bigger difference than a really nice amp. Some hams can't afford to put up a fancy antenna system so they have to get their gain via amplification, some can't afford the amp but can afford to put up a well-dressed antenna. The point is we get our kicks in different ways. QRO has a rewarding feel when you realize you need to replace your 2000 watt wattmeter, or watching a pair of 3-500Z tubes turn color. I'll be the first to admit that I like running a 1000 watt CW signal and the full legal limit on SSB. But it isn't necessary to exceed 1000 watts PEP - I wish it made a difference but it doesn't. Pay close attention to the Decibel below to understand why.The Decibel
More important than anything else that a ham should know is what the decibel is. Too few hams understand why a 5 watt signal can reach from Boston to Sacramento when 20 meters has almost folded for the evening.When it comes to running lots of power - "Biger's better, crank it up and dim the lights!" Well, that's true to a point, but knowing where that "point" is and how to find it can sometimes be confusing. Fortunately for us, defining where the "point" is can be defined with simple terms. The "point" that we reach where more power makes little difference is, for hams, around 1000 watts. Anything over 1000 watts is mostly pouring sand down a rat hole. It took a long time for this to soak into my brain... Why is this true? The decibel!It is difficult for a person, especially most new hams these days, to fully appreciate the decibel. Wattmeters make it easy to see a large change in output power by watching the needle move its entire distance but this change doesn't really mean much when you think about what amplification really is. For a person to increase their output power level by 3dB, you must double your power output. For 9dB gain you must multiply your current power output by 8. For SSB operation you need approximately 10dB gain (precisely 1.67 S-units, 10x your output power) to make a clearly noticeable improvement to the person listening on the other side. So what does this mean in plain English?
For hams saying QRP is a waste of time, a 5 watt radio is only about 2 S units below someone running around 100 watts:
- 5 watts output x 8 = 40 watts (this is 9dB gain)
- 40 x 2 = 80 watts output = 12dB total gain (only 2 S units over 5 watts output!)
2 S units below a 100 operator is typically a 559 report
vs 579 report. And if the band is going down for the day the dB attenuation
(30dB or more) far exceeds what we are able to dump into the air.
For hams who typically run 80-140 watts output:
For hams who typically run 80-140 watts output:
- 10 watts output x 8 = 80 watts (this is 9dB gain)
- Typical ham running 80 watts output x 8 = 640 watts (this is another 9dB gain)
- Contester running 640 watts output x 8 = 5120 watts (this is another 9dB gain)
To make a real difference to the receiving station, 5120
watts are needed over 640! That's a kick in the pants, eh? But what about SSB
operation and 10dB gain? More numbers:
- 10 watts output x 10 = 100 watts (this is 10dB gain)
- 100 watts output x 10 = 1000 watts (this is 10dB gain)
- 1000 watts output x 10 = 10000 watts (this is 10dB gain)
It's getting worse by the minute! A typical rig at 100
watts makes a big splash at 1000 watts... but requires 10,000 watts for the
same sized jump from 1,000? Yes! And for some reason, thousands more dollars
are spent to get a 2500 watt amplifier instead of a 1300 watt amplifier - but
why??
QRO Power!
Okay, well, there is some creedence to a 2500 watt
amplifier. It's bigger than your friends' amps, you can have your own lightshow
on demand by simply keying it and watching your neighborhood's lights dim, you
can prove to yourself that it's really getting you around the world because
your electricity bill is $200 a month more than it used to be... and it's
heavier. Oh yes, there's also another 3dB going out the line but whether or not
you have melted or burned things in-line or caused your neighbors' ground-fault
interruption system to trip from induced current is another matter. There are
those among us who will claim that the additional 3dB makes the difference
between a successful or unsuccessful contact - possibly for CW but highly
doubtful for any other mode. The only thing you get out of a "Really
Big"(tm) amplifier is bringing up the signal strength (aka,
"loudness") of your conversation when you are not yelling into the
microphone at 100% modulation. Most conscientious hams will use a little
processing to compress their speech and improve intelligibility. So at an
average conversation level of 60 watts PEP and using the formula above we get
the figures below:
- 60 x 10 = 600 watts (10dB, 2 S Units)
- 600 x 10 = 6000 watts
I did not mention above, but no radio will show a linear S-unit gain for each 5dB of signal. Search hard enough and you will find that various brands of radios will need only 2dB for the first 3 S-units, 5dB for the next 4 and so on - others have a completely diferent pattern. You have to use your own judgement and base RST how much stronger the remote station is above the noise floor.
If you want to know if your amp is splattering, use what I call the "Wave Meter" - wave at your neighbors; if they wave back you're okay
ΑΚΟΥΩ ΣΕ ΕΛΛΗΝΙΚΑ ΠΗΓΑΔΑΚΙΑ ΠΟΛΛΟΥΣ ΕΛΛΗΝΕΣ ΡΑΔ/ΝΕΣ ΝΑ ΧΡΗΣΙΜΟΠΟΙΟΥΝ ΤΕΡΑΣΤΙΕΣ ΙΣΧΕΙΣ (> 500 ) ΓΙΑ ΕΠΑΦΕΣ ΕΝΤΟΣ ΕΛΛΑΔΟΣ !!!
Το πρώτο ερωτημα που μου ερχεται στο μυαλο ειναι : 1. Γιατι οι εταιρίες φτιαχνουν πολυ ακριβα μηχανηματα που εκπεμπουν με 100 watt μονο?
Πολλα μηχανηματα με ισχή 100 watt κοστιζουν 10.000 Ευρώ
Βεβαιως μια απο τις απαντησεις ειναι η εξής: Για να σου πουλήσουν και εναν ακριβο ενισχυτη.
Αλλη μια μοδα ειναι το εγω το εχω ποιο μεγαλο ?
Απο τοτε που βγηκαν οι λάσπες τα αγορακια εχουν αυτο το κομπλεξ.
Το : Ποιος ειναι ο καλύτερος ειναι κατι που τυραναει τους ανδρες απο το DNA τους.
Και βεβαια ειναι στο DNA των ανδρών αυτο, γιατι υπερισχύει ο νόμος του Δαρβίνου .
Το καλυτερο DNA θα επιβιώσει.
Ετσι λοιπον ξεκιναει μια ιστορια 10.000 ετων που δεν ειναι Ραδιοερασιτεχνική αλλά Ανδρική θα μπορουσα να πω hi.
Κι ομως κι εγω θα παω διακοπες το καλοκαιρι με autostop κι εσυ με την Rolls . και ειναι το ιδιο πιθανον να περασω καλυτερα με το κοριτσι μου απο ότι εσυ με την γρια σου στην Rolls hi .
Ομως καλο θα ηταν να σταματησω το προκλητικο γραψιμο και να μπω στην ουσία του θέματος μου.
| under construction |
YAESU FL 2100B
some read about 1200 input and think they will have 1KW out..
No
550w out is good for this linear on 1200 input. Max and ideal would be 600w and don't expect more. But take care, do not exceed 100w input peaks ! Οtherwise will damage some components and eventually the valves . Don't forget you have 2400 volts there ! it's the top for 572Bs !! good dx and before all these, take serius care on your antenna efficiency.
17.5.19
SDR wins - Elecraft K4 upcoming
look this page first . Its very interesting
https://044640f.netsolhost.com/?fbclid=IwAR385mutVG7LHrLBO2yeBk0TwEk9B2R0_9N0A6kMiTLJxR6fSOsICjMaNWg
I'm not close in idea to buy everything new, but the K4 its interesting
Elecraft K4
OVERVIEW
A direct-sampling SDR you’ll love to useOur new K4 harnesses the latest in signal processing while retaining the best aspects of the K3S and P3. The resulting user interface makes the technology transparent, allowing you to focus on working the world.
160-6 meter, all-mode coverage & dual RX
The K4 includes dual receive over 100 kHz to 54 MHz. Since it utilizes direct sampling, there’s no need for crystal filters in the K4 or K4D (see Models, back page). For extreme-signal environments, we offer a dual superhet module (standard in the K4HD). An internal VHF/UHF module is also planned.
High-resolution mini-pan for each receiver
Our advanced fine-tuning aid, with its resampled bandwidth as narrow as +/- 1 kHz, is displayed separately from the main panadapter. You can turn it on by tapping either receiver’s S-meter or by tapping on a signal of interest.
Simple operation and setup
The K4 features a large, full-color touch display, combined with a rich set of real controls. Per-VFO transmit metering makes split mode completely foolproof. Band-stacking switches and per-receiver controls are both intuitive and versatile, adapting to operating context. Usage information on these and other features is just one tap away, thanks to our built-in help system.
Rich I/O complement
The rear panel includes all the RF, analog and digital I/O you’ll need to complete your station. All K-line accessories are supported, including amps, ATUs, and our K-Pod station controller. The HDMI video output supports an external display with its own user-specified format.
Full remote control from multiple devices
The K4 can be 100% remote controlled, via Ethernet, from a second K4 as well as a PC, notebook, or tablet. Panadapter data is included on all remote displays.
Modular hybrid architecture
The K4 adapts to your needs, with three models to choose from:
- Basic K4 with wide-range dual receive
- K4D with diversity receive
- K4HD with a dual superhet module for exceptional dynamic range
Fast signal processing
The RF signal chain in the K4 incorporates parallel hardware processing of data streams, including a dedicated DSP subsystem. This, combined with silent, PIN-diode T/R switching, ensures fast CW break-in. Data and speech-processing delays are also minimized.
Standard DSP features include easy-to-adjust, per-mode RX/TX EQ; clean, punchy RF speech processing; full DVR capabilities; and several built-in data decode/encode modes. Direct-sampling technology results in an ultra-flat passband response for clean RX and TX audio. Since the signal chain is software-defined, the DSP can be field upgraded to add new algorithms and operating modes.
The KAT4 ATU has a nominally 10:1 matching range. It includes 3 antenna jacks, any one of which can be selected as an input for one or both receivers.
Internal VHF/UHF module (future option)
An expansion slot is reserved for a high-performance VHF/UHF module, with output of approximately 15 W. This module will support all modes.
Kit version
A no-soldering kit version of the K4 is planned for later release. Builders will learn about advanced radio technology as they proceed. All modules are pre-aligned and tested.
MODELS
The K4 adapts to your needs, with three models to choose from.| Model K4 | Model K4D | Model K4HD |
| Basic K4 transceiver provides 160-6 m, all-mode coverage; 100 W output; five receive RF sources; and wideband dual watch, allowing the main and sub receivers to be set for the same or different bands. | Adds KDIV4 option, with a second set of band-pass filters and additional direct-sampling ADC module. This allows the two receivers to use different antennas – a requirement for diversity receive. Having two sets of band-pass filters also optimizes signal handling when the receivers are on different bands and/or antennas. | Includes
all of the above, plus our dual superhet module, the KHDR4. Ideal for
competitive field day, contesting, and DXpedition stations. Each
superhet receive section includes two crystal filters: one SSB/data
bandwidth, one CW bandwidth. The superhet’s 8 MHz IF has excellent dynamic range, so additional crystal filters are not required.
STANDARD FEATURES Size: 4.5”H x 13.5”W, 10” D Weight: Approx. 10 lbs Supply Voltage: 12-15 VDC Current: ~2 A RX, ~18-23 A TX Frequency Range: 100 kHz – 54 MHz (VHF/UHF range to be determined*) Stablility: +/- 0.25 ppm (TCXO) Modes: CW, SSB, AM, FM, Data LCD: 7” color; touch & mouse control Text modes: CW, PSK31/63, RTTY KAT4 ATU: 10:1+ range; 3 ant. jacks RX antenna sources: Up to 5 A-to-D Converter(s): 16 bits I/O: USB-A x3, USB-B (two virtual com ports + audio), RS232 (DE9), Ethernet, HDMI. front/rear mic, front/rear phones, LINE in/out, speakers, PTT in, KEY out, paddle, key, ACC,12 V out. CW QSK: Silent, PIN-diode switched Other: RX/TX EQ, real-time clock,100% remote control including panadapter data, remote antenna switch control*, custom in-box software apps* |
14.4.19
DMR digital communications dependable to web
MMDVM Digital Voice Modem Jumbo Spot Hotspot
communication over interneti m transfer RF signal to the local repeater using internet with wired PC and through the network going on any capable radio repeater at any place in world.
That way people from the other side of the globe can speak very easy with me ..
1.3.19
Late story of R-390A: the R725/URR and the Tropicon project..
Last tests with Collins R-390A
17 JAN 2021
-------------------------------------------
Every one knows the legend Collins R-390A /URR as well R-389
There is more story named R-725/URR
reproduction
Arvin
Industries, Inc. - R-725/URR
Here is the story, from Henry Rogers at the Western Radio Museum here: http://www.radioblvd.com/MilitaryCommunicationsGear.htm
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The R-725/URR is a 1967 Electronic Assistance Corporation-built R-390A receiver that was modified (in 1967) by Arvin Industries, Inc. for the USAF to use in semi-portable radio direction finding systems. Each R-725 receiver had the following modifications installed. First, the standard R-390A IF module was replaced with a new manufacture Series 500 IF module built by Arvin Industries or Servo Electronics. The Series 500 IF module was essentially a R-390 IF module (six IF amplifiers with no mechanical filters) that had minor updates to coax connectors to allow the Series 500 IF module to be installed with no modifications to the R-390A circuitry. However, further design development for the R-725 modification turned up a 60hz modulation problem that required additional modifications. A small chassis is mounted in the main frame space directly in front of the power supply module. This chassis has a 25vac transformer, two resistors and a connector-harness. This was a "hum-bucking" transformer that basically disconnected the VFO tube, the BFO tube and the ballast tube and powered the tube heaters with a "floating" 25vac (not referenced to chassis) and then used the resistive divider connected to B+ to "swamp" the AC with DC. The result was these tube heaters and ballast tube series string operated on +25vdc. To further protect the PTO from 60hz hum pickup, the entire PTO case had a grounded ferrous metal shield installed. The final modification was to the IF Output connector. The larger Series 500 IF module prevented connecting the IF Output cable to the back connector due to lack of clearance. A special "low profile" right-angle coax fitting was installed that allowed the IF Output to be available at the back panel. The contract number for the R-725/URR was DAAB05-67-C-2338 with a total number of receivers modified being less than 300.
The Non-Secret R-725 Story - The purpose of the R-725 mods was for compatibility with military portable direction finders that used four vertical antennae per installation along with three receivers. The DF system used went back to the Bellini-Tosi type of DF set-up that used two crossed loop antennae with a rotating loop inside to create a radio-goniometer. Bellini and Tosi had discovered that crossed loop antennae would "re-radiate" the signal they were receiving within the small field inside the antenna's space. The "re-radiated" signal retained all of the directional properties of the original signal and could be measured for varying signal intensity dependent on direction. The crossed loop antenna size didn't affect the frequency of operation allowing for reduction in the size of DF loops on LW. The original Bellini-Tosi system dated from around 1900 and the system was sold to the Marconi Company around 1907. By the early twenties, vacuum tube amplifiers were being added to increase performance capabilities of the DF antennae systems. The most common B-T DF systems used the crossed loops but some larger systems used the four-square vertical antenna system. This system was developed by Adcock during WWI and because the connections to and from the four square verticals were underground it didn't respond to skywave propagation and allowed ground wave DFing over long distances. The B-T DF and Adcock systems continued to evolve and improve with the systems being used throughout WWII. During WWII, oscilloscope displays began to be used for direction indications. After WWII, larger DF systems continued to be developed up to the mammoth "elephant cage" antennae ("Wullenweber" was the actual name) that were over a thousand feet in diameter and consisted of several "rings" of circular antennae all working to provide accurate DFing over great distances and wide frequency spans. By the 1990s, most of these large arrays were becoming obsolete and nowadays most have been dismantled.
The mechanical filters used in the R-390A resulted in signal path phase shifts that caused errors to show up in the DFing electronics. When used with the four square antennas, the low frequency modulation added via the radio-goniometer interacted with the mechanical filters creating the error. Early versions of this DF set-up had used R-390 receivers and the radio-goniometer was located quite a distance from the receivers to reduce any interference. In the 1960s, the USAF wanted to reduce the size of the entire DF system so it could be towed around on a trailered hut. This meant the radio-goniometer had to be in the same room as the receivers. This was going to require some protection to certain receiver circuits. The R-390 had been out of production for several years, so the solution was to design the new portable system to use modified R-390A receivers that could be easily purchased. Arvin Industries was the main contractor with Servo also doing some rework. The modified receivers would have the Series 500 IF module, essentially a R-390 IF module that was slightly updated to not require any rework to the R-390A receiver it was installed into. That eliminated the mechanical filter phase shift problem. Additionally, with the close proximity to the radio-goniometer, a 60hz hum appeared on the PTO tube filament and that also interfered with the LF modulation of the DF system. A special "hum bucker" chassis was added to the receiver that essentially operated the VFO tube, the BFO tube and the 3TF7 Ballast tube on +25vdc. Also, a grounded ferrous metal shield was added to the PTO housing to prevent hum "pick up." Arvin bought new R-390A receivers in 1967 direct from Electronic Assistance Corporation and the modifications were installed at Arvin. When complete, the receiver was tagged as "R-725/URR." The tags will generally show Arvin Industries as the contractor but sometimes Servo Electronics will be encountered. Arvin ink-stamped a serial number on each Series 500 IF module and when that module was installed into the receiver that same serial number was stamped onto the front panel data plate.
The Secret Project - Was there another purpose that was the "real" reason that the R-725 was created? According to an article that appeared in Electric Radio in January 2006 by Chuck Teeters, there was a "top secret" purpose for the R-725 and the receiver "mods" were primarily created for that "secret" project. The R-725 was a product that resulted from the Cold War jamming that was common between the USA and the USSR. In the mid-to-late 1960s, the NSA, the USAF and the Signal Corps were developing a new system called "Tropicom" that was an upgrade to the antennas and transmitters to improve HF communications for the military. The Tropicom upgrades also included the incorporation of the "F9c" anti-jamming/crypto system. The F9c system used a spread spectrum transmission of digital noise and signal that ran through a digital encrypo-key generator that had 144 stages of looped-feedback that also fed through phase modulators to maintain proper phase relationships of the signal and noise. When recombined at the receive end the signal to noise extracted the signal and left the noise and any jamming attempts far below the signal level. Since the system used spread spectrum, the signal couldn't be detected without the proper combination of equipment and decryption and that left any jamming attempts at just "blind" shots. However, when the F9c was used with a R-390A on the receive end, the phase changes in the mechanical filters interfered with the recombination process and the system didn't work. When used with R-390s with a standard IF amplifier circuit, the F9c system worked fine.
Since the R-390 receivers dated from the early-1950s, there were only a limited supply of those receivers still available and those that were available needed constant maintenance. The ultimate solution was to have new R-390A receivers with newly-built R-390 IF modules installed available for the Tropicom system.
In order to keep the F9c project "secret," the actual use of the R-725 couldn't be known to those outside the Tropicom project. Since there really was the Adcock DF system upgrades that really did need a non-mechanical filter type R-390A, the R-725 was directed to be built for the DF purpose only. However, those running the F9c project had the R-725 order quantity doubled and half of the R-725 receivers were procured for F9c use while the other half went to the DF systems. The secret classification stayed on with the F9c system and it was used for quite a long period with many upgrades over the years. So, even though half of the R-725 receivers were used in direction finders, the other half had a "secret life" used in the anti-jamming/crypto communications world of the NSA, the USAF and the Signal Corps.
Performance - The R-725/URR is very much like listening to a R-390 receiver. The modifications to the VFO-BFO heaters using the "hum-bucker" are not audible. The big change is the Series 500 IF module. With six IF amplifiers, the R-725 has plenty of gain. So much, that most strong signals will push the Carrier Level meter to 70db or 80db and then if the receiver is tuned off of the signal, the meter drops to 20db or less. I have the IF gain reduced by 40%. Audio sounds slightly different than the R-390A with mechanical filters but still there is lots of selectivity and QRM is not a problem. The R-725 is basically like having an R-390 without all of the maintenance headaches.
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The R-725/URR is a 1967 Electronic Assistance Corporation-built R-390A receiver that was modified (in 1967) by Arvin Industries, Inc. for the USAF to use in semi-portable radio direction finding systems. Each R-725 receiver had the following modifications installed. First, the standard R-390A IF module was replaced with a new manufacture Series 500 IF module built by Arvin Industries or Servo Electronics. The Series 500 IF module was essentially a R-390 IF module (six IF amplifiers with no mechanical filters) that had minor updates to coax connectors to allow the Series 500 IF module to be installed with no modifications to the R-390A circuitry. However, further design development for the R-725 modification turned up a 60hz modulation problem that required additional modifications. A small chassis is mounted in the main frame space directly in front of the power supply module. This chassis has a 25vac transformer, two resistors and a connector-harness. This was a "hum-bucking" transformer that basically disconnected the VFO tube, the BFO tube and the ballast tube and powered the tube heaters with a "floating" 25vac (not referenced to chassis) and then used the resistive divider connected to B+ to "swamp" the AC with DC. The result was these tube heaters and ballast tube series string operated on +25vdc. To further protect the PTO from 60hz hum pickup, the entire PTO case had a grounded ferrous metal shield installed. The final modification was to the IF Output connector. The larger Series 500 IF module prevented connecting the IF Output cable to the back connector due to lack of clearance. A special "low profile" right-angle coax fitting was installed that allowed the IF Output to be available at the back panel. The contract number for the R-725/URR was DAAB05-67-C-2338 with a total number of receivers modified being less than 300.
The Non-Secret R-725 Story - The purpose of the R-725 mods was for compatibility with military portable direction finders that used four vertical antennae per installation along with three receivers. The DF system used went back to the Bellini-Tosi type of DF set-up that used two crossed loop antennae with a rotating loop inside to create a radio-goniometer. Bellini and Tosi had discovered that crossed loop antennae would "re-radiate" the signal they were receiving within the small field inside the antenna's space. The "re-radiated" signal retained all of the directional properties of the original signal and could be measured for varying signal intensity dependent on direction. The crossed loop antenna size didn't affect the frequency of operation allowing for reduction in the size of DF loops on LW. The original Bellini-Tosi system dated from around 1900 and the system was sold to the Marconi Company around 1907. By the early twenties, vacuum tube amplifiers were being added to increase performance capabilities of the DF antennae systems. The most common B-T DF systems used the crossed loops but some larger systems used the four-square vertical antenna system. This system was developed by Adcock during WWI and because the connections to and from the four square verticals were underground it didn't respond to skywave propagation and allowed ground wave DFing over long distances. The B-T DF and Adcock systems continued to evolve and improve with the systems being used throughout WWII. During WWII, oscilloscope displays began to be used for direction indications. After WWII, larger DF systems continued to be developed up to the mammoth "elephant cage" antennae ("Wullenweber" was the actual name) that were over a thousand feet in diameter and consisted of several "rings" of circular antennae all working to provide accurate DFing over great distances and wide frequency spans. By the 1990s, most of these large arrays were becoming obsolete and nowadays most have been dismantled.
The mechanical filters used in the R-390A resulted in signal path phase shifts that caused errors to show up in the DFing electronics. When used with the four square antennas, the low frequency modulation added via the radio-goniometer interacted with the mechanical filters creating the error. Early versions of this DF set-up had used R-390 receivers and the radio-goniometer was located quite a distance from the receivers to reduce any interference. In the 1960s, the USAF wanted to reduce the size of the entire DF system so it could be towed around on a trailered hut. This meant the radio-goniometer had to be in the same room as the receivers. This was going to require some protection to certain receiver circuits. The R-390 had been out of production for several years, so the solution was to design the new portable system to use modified R-390A receivers that could be easily purchased. Arvin Industries was the main contractor with Servo also doing some rework. The modified receivers would have the Series 500 IF module, essentially a R-390 IF module that was slightly updated to not require any rework to the R-390A receiver it was installed into. That eliminated the mechanical filter phase shift problem. Additionally, with the close proximity to the radio-goniometer, a 60hz hum appeared on the PTO tube filament and that also interfered with the LF modulation of the DF system. A special "hum bucker" chassis was added to the receiver that essentially operated the VFO tube, the BFO tube and the 3TF7 Ballast tube on +25vdc. Also, a grounded ferrous metal shield was added to the PTO housing to prevent hum "pick up." Arvin bought new R-390A receivers in 1967 direct from Electronic Assistance Corporation and the modifications were installed at Arvin. When complete, the receiver was tagged as "R-725/URR." The tags will generally show Arvin Industries as the contractor but sometimes Servo Electronics will be encountered. Arvin ink-stamped a serial number on each Series 500 IF module and when that module was installed into the receiver that same serial number was stamped onto the front panel data plate.
The Secret Project - Was there another purpose that was the "real" reason that the R-725 was created? According to an article that appeared in Electric Radio in January 2006 by Chuck Teeters, there was a "top secret" purpose for the R-725 and the receiver "mods" were primarily created for that "secret" project. The R-725 was a product that resulted from the Cold War jamming that was common between the USA and the USSR. In the mid-to-late 1960s, the NSA, the USAF and the Signal Corps were developing a new system called "Tropicom" that was an upgrade to the antennas and transmitters to improve HF communications for the military. The Tropicom upgrades also included the incorporation of the "F9c" anti-jamming/crypto system. The F9c system used a spread spectrum transmission of digital noise and signal that ran through a digital encrypo-key generator that had 144 stages of looped-feedback that also fed through phase modulators to maintain proper phase relationships of the signal and noise. When recombined at the receive end the signal to noise extracted the signal and left the noise and any jamming attempts far below the signal level. Since the system used spread spectrum, the signal couldn't be detected without the proper combination of equipment and decryption and that left any jamming attempts at just "blind" shots. However, when the F9c was used with a R-390A on the receive end, the phase changes in the mechanical filters interfered with the recombination process and the system didn't work. When used with R-390s with a standard IF amplifier circuit, the F9c system worked fine.
Since the R-390 receivers dated from the early-1950s, there were only a limited supply of those receivers still available and those that were available needed constant maintenance. The ultimate solution was to have new R-390A receivers with newly-built R-390 IF modules installed available for the Tropicom system.
In order to keep the F9c project "secret," the actual use of the R-725 couldn't be known to those outside the Tropicom project. Since there really was the Adcock DF system upgrades that really did need a non-mechanical filter type R-390A, the R-725 was directed to be built for the DF purpose only. However, those running the F9c project had the R-725 order quantity doubled and half of the R-725 receivers were procured for F9c use while the other half went to the DF systems. The secret classification stayed on with the F9c system and it was used for quite a long period with many upgrades over the years. So, even though half of the R-725 receivers were used in direction finders, the other half had a "secret life" used in the anti-jamming/crypto communications world of the NSA, the USAF and the Signal Corps.
Performance - The R-725/URR is very much like listening to a R-390 receiver. The modifications to the VFO-BFO heaters using the "hum-bucker" are not audible. The big change is the Series 500 IF module. With six IF amplifiers, the R-725 has plenty of gain. So much, that most strong signals will push the Carrier Level meter to 70db or 80db and then if the receiver is tuned off of the signal, the meter drops to 20db or less. I have the IF gain reduced by 40%. Audio sounds slightly different than the R-390A with mechanical filters but still there is lots of selectivity and QRM is not a problem. The R-725 is basically like having an R-390 without all of the maintenance headaches.
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