Rejseradio

Hej herinde.
Jeg står foran en række kortvarige udsendelser til bl.a. Afrika og Asien, og har derfor brug for lidt rådgivning i forbindelse med anskaffelse af en lille kortbølgemodtager.

Jeg havde for år tilbage en Sony SW7600, som var perfekt til formålet, men den led desværre "kondensatordøden" efter ikke at have været brugt i et antal år. Den nyanskaffede Tecsun PL680 er jeg på ingen måde imponeret over når det drejer sig om MW/SW, selv når den er koblet til "Jensens tørresnor" (den høje HF-antenne).

Er der herfra nogen forslag?
På forhånd tak

Bent Jensen

Svar til #1:
Jeg har ikke selv prøvet denne her, men måske andre her på BG har?

https://www.batteribyen.dk/nedis-ukw-radio-1-5w- verdensmodtager-alarmfunktion-gra-4

Gert / OZ4ZG

Svar til #1:
TECSUN kunne være et godt bud.

Svar til #1:
En af dem her, jeg har selv en mindre og ældre udgave, den er ret god.
https://www.sangean.com/en/products

ATS 909 serien måske.

Svar til #1:
Sony'en var min faste rejseven i mange år, da Radio Danmark sendte.
Altid friske nyheder hjemmefra.
Men også den led kondensatordøden.
På ebay købte jeg et kit med samtlige lytter og en leed (til erstatning af skalapæren). Det kræver lidt lodde-skills. Men Sonyen var "oppe" igen.
Ole
OZ8OE

Svar til #1:
Køb ikke for billigt. Du skal helst op i noget i retning af Qodosen SR-286 eller DX-286 - den sidste er lidt billigere fra ny, og i hvert fald li'så god. Jeg har SR-286 og den er go' - evt med en lidt større antenne end den indbyggede.

Andre muligheder er en TEF6686 som jeg ikke selv har erfaringer med.

Svar til #1:

Hej Bent

Måske et dumt spørgsmål ;
Hvad er "kondensatordøden" ?


/søren/4zat

Svar til #1 (#4):

Jeg ville foreslå Sangean ATS 909X2 - de tidligere varianter har kunnet modtage SSB - siden Sangean ATS 909:

https://www.radiomuseum.org/r/sangean_ats_909_at s909.html

Sangean ATS 909X2 - her er også en US-engelsk manual til download:
https://www.sangean.com/en/product/ats-909x2-gra phite
Fra manual - sørg derfor for at den har version 078 eller nyere:
Citat: "...
The radio's software version can be shown both in the menu and by performing these steps:
1. Make sure the radio is powered off.
2. Press the Enter button (30), the radio shows the software version on its display.
The version display cannot be altered and is just for your reference
..."

2021, Dan Robinson reviews the Sangean ATS-909X2:
https://swling.com/blog/2021/04/dan-robinson-rev iews-the-sangean-ats-909x2/
Citat: "...
First, let’s get the elephant in the room out of the way. Although I have not undertaken detailed technical testing of the 909×2 – nor do I have the equipment to carry this out – it does seem that Sangean may have finally tackled this crippling flaw that rendered the old 909x nearly useless when using it only on the whip. I’ll undertake further testing and comparisons with some of my other portables to confirm this. The whip antenna itself is robust – solid and long, something that Tecsun could take note of.
...
SIGNS OF LONGWAVE RECEPTION PLAGUED BY CROSS-MOD FROM MEDIUMWAVE
...
ALERT FOR SANGEAN AND ALMOST A DEAL BREAKER – as mentioned in the Zantow review, and in other comments I have seen on the 909×2, the drop in level from AM to LSB is a killer negative.
..."

Reviews For: Sangean ATS909X2:
https://www.eham.net/reviews/view-product/15798
Citat: "...
2024-04-02
...
Oh, the software version on my 909X2 states VER 078. I thought it only went up to 073 but maybe they've improved this radio even more...
..."

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Prissammenligninger - de burde være sorteret på farve men ser ikke ud til at være det:
https://www.pricerunner.dk/pl/317-3200163039/Rad ioer/Sangean-ATS-909X2-Sammenlign-Priser
Tyskland:
https://www.idealo.de/preisvergleich/OffersOfPro duct/201110185_-ats-909x2-sangean.html
https://www.idealo.de/preisvergleich/OffersOfPro duct/201110186_-ats-909x2-schwarz-sangea n.html
https://www.idealo.de/preisvergleich/OffersOfPro duct/201110187_-ats-909x2-weiss-sangean. html

Svar til #1:

En lang/kort-trådantenne trækker en masse nærfeltsstøj ind på mellembølge og langbølge.

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Inspiration til afstemte og bredbånds mellembølgeantenner som IKKE burde trække nærfeltsstøj ind.

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Jo større diameter jo mere følsom. Jeg lavede en ca. 1,4 meterØ indendørs-loop med to vindinger uafstemt via skærmet twinax kabel med en 1:4 balun og jeg trak britiske stationer ind i fin lydkvalitet, for nogle år siden, med lav støj. Den danske station i kbh på 208 meter/1440kHz kunne også høres i fin lydkvalitet med lav støj. Det var bedre end med den indbyggede ferritantenne som normalt er god (lav støj).

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Den bedste mellembølgeantenne - se billederne - modtageren blev specialdesignet til at fungere i USA-højhuse med masser af nærfeltsstøj lige efter anden verdenskrig. Jeg har kopieret tekst fra:
https://groups.io/g/loopantennas/message/18913

If you have any interest in an antique commercial screened medium wave loop-antenna, then read this page. Look at how the loop-antenna is made:

Hotel Radio:
Muligvis: "Hotel Radio Corporation model 6A":
https://www.angelfire.com/electronic/funwithtube s/mystery_radio.html
backup:
https://web.archive.org/web/20240317095324/https ://www.angelfire.com/electronic/funwitht ubes/mystery_radio.html
Citat: "...
It appears to be a "Hotel Radio Corporation" model 6A. This was a coin activated radio. After the end of World War II the owners of high rise hotels received complaints from guests that radio reception in the rooms was very poor. The problem was a combination of weak signals due to the structural steel in the building combined with electrical interference. The HRC was formed to design and manufacture a radio with an RF stage and very good immunity to electromagnetic interference. The head of the HRC was a man named Frawley. Some of the radios sold by the Hotel Radio Co. had the Frawley brand name on a decal. The rest of them carried the name of the hotel they were sold to.
...
I had already guessed that the big knob controlled a rotating loop antenna and I was right but there turned out to be more to it than that. The loop is electrostaticly shielded. To allow the magnetic field to penetrate the box and induce a current in the loop there must not be a complete current path around the box. If there were it would be like a shorted turn in a transformer and there would be little signal induced in the loop. The horizontal strips of aluminum foil are broken on one side of the box. The bar in the bottom picture ties the top and bottom aluminum sheets together but it does not contact the foil strips.
...
This is without a doubt the best performing AM radio I have ever encountered. No doubt it was quite expensive for its day and probably very few were sold to private owners. Even the hotel market was likely rather small and, apparently, few from that source have survived making it rare.
..."

Den har seks elektronrør:
https://www.radiomuseum.org/r/hotelradio_6a.html

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The Screened Loop Aerial* - Nonstop Systems:

THE WIRELESS ENGINEER
October, 1939
The Screened Loop Aerial*
A Theoretical and Experimental Investigation
By R. E. Burgess, B.Sc.
(Radio Department, National Physical Laboratory)
SUMMARY.-This paper describes a theoretical and experimental investigation of the screened loop type of receiving aerial used in direction-finding and field-strength measurement.
The theory of the screened loop is analysed and the simplifying assumptions made are indicated, and are shown to lead to a good first approximation for the value of pick-up for the screened loop. The pick-up is computed for the special cases of the screen gap short circuited, capacitively loaded, and tuned. It is shown that enhanced pick-up maybe obtained by the suitable capacitive loading of the gap in preference to an increase of the number of loop turns, and thepractical aspect of this systemis discussed.
Confirmatory experiments are described, and the paper concludes with an indication of a suggested continuation of the investigation.
https://www.nonstopsystems.com/radio/pdf-ant/art icle-antenna-magloop-Scrn-Lp.pdf
backup:
https://web.archive.org/web/20220121115400/https ://www.nonstopsystems.com/radio/pdf-ant/ article-antenna-magloop-Scrn-Lp.pdf

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Alt som er magnetisk “ferrous” - fx jern - er dårligt at anvende til loops og i nærheden (helst 2xdiameter eller mere væk), da de absorberer de hurtige vekslende HF-magnetfelter.

SMALL LOOP ANTENNAS.
An Overview of the Underestimated Magnetic Loop HF Antenna.
Leigh Turner VK5KLT.
https://www.qsl.net/vk5bar/Small%20Loops%20-%20M ike%20Underhill%20KLT%20&%20BR/Leigh%27s %20docs/small__loop__antennas-VK5KLT.htm
Citat: “…
Similarly when ferrous / iron material is too close, the magnetic near-field of the loop will induce by transformer action a voltage across the RF resistance of the material causing a current flow and associated I2R power loss. This situation might for example arise when the loop is mounted on an apartment balcony with nearby iron railing or concrete rebar etc; the deleterious influence can be minimised by simply orienting the loop to sit at right angles to the offending iron or steel material.
…”

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Med diagrammer - ikke testet, men er aktiv og bredbåndet. I stedet for en ferritantenne kan en fx to x en vinding anvendes. Der skal dog være en skærm mellem de to viklinger:

Wideband ferrite longwave/middlewave/lower shortwave-antenna:
The positive feedback provided by the feedback current lowers the antenna impedance which, in turn, increases the effective area of the antenna:
https://patentimages.storage.googleapis.com/pdfs /US5296866.pdf
Quote: "...
The outstanding stability of this active antenna
...
The reason why an antenna with regeneration has greater sensitivity than one without regeneration may be understood in terms of the concept of antenna “effective area.”
...
It is yet another object of this invention to provide an improved broadband active antenna system.
...
It is desirable to have a very sensitive antenna for the purpose of detecting low level fields, e.g., low level magnetic fields. It is also desirable to have this sensitive antenna exhibit a broadband frequency characteristic for, among other reasons, to satisfy the requirements of modern, fast-Fourier transform data analysis instruments, where it is often advantageous to analyze broad-band signals rather than single-frequency or narrow hand signals. For example, the antennas commonly employed for sensing ELF magnetic fields consist of search coils comprised of several thousand turns of copper wire wound around high permeability, low loss cores, such as ferrite rods.
..."

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Kig på denne side - bladr ned til "INTRODUCTION". I højre side ses en skærmet rammeantenne.
Hans design undgår en transformator; derfor den store båndbredde 200kHz - 150MHz:

PA3GZK's WIDE BAND ACTIVE LOOP RECEIVING ANTENNA:
https://www.pa0fri.com/Ant/Active%20antenna/Acti ve%20receiving%20%20loop%20antenna%20eng .htm
Citat: "...
This antenna is much less affected by fading (QSB) as a dipole or other similar antennas. The E-field in the near field that causes the most interference is very well suppressed, because the antenna within this field will primarily responsive to the H field
..."

Husk der skal være et gap i skærmen foroven - ellers svagere signal ("kortsluttet" rammeantenne)!
Det smarte ved en skærmet rammeantenne til kortbølge er, at den kun kan koble til radiobølgers magnetiske felter.
Skærmen skærmer effektivt for elektriske felter - incl. elektrisk nærfeltsstøj.
Hvis rammeantennens indre isolerede leder skal anvendes ved højere frekvenser end fx 30MHz, bør denne leder være isoleret med (opskummet) polyethylen eller PTFE/teflon. Lederen kan fx være inderlederen med isolering fra satellitkabel?

Svar til #7:
Hej Søren.
Jeg har et par Sony ICF 7600 fra 1990 de fungerer stadig upåklageligt på indbyggede batterier -har aldrig prøvet udvendig strømforsyning.
" kondensatordøden ?"--- " Google " stephan.win 31.de/ sony 76-2 htm"--- her er en masse om ?defekte? kondensatorer i modtageren - måske heraf udtrykket "kondensatordøden" hvis man ikke finder fejlen.
Asbjørn // OZ6AI

Svar til #1:
Hej alle.
Tak for svarene, nu vil jeg prøve at kigge lidt nærmere på de forskellige modeller. Tak til Glen for indslaget omkring antenner. Det er klart, at der er væsentlig mere støj nu, end der var da jeg brugte Sony'en for 30 år siden. Alene LED synes jeg, gør modtagelse vanskeligt om aftenen.

Hvad angår "kondensatordøden" har jeg fået det indtryk, at når gamle elektroniske apparater med elektrolytter har stået for længe, taber de pusten. Sony'en kunne, da den blev tændt for et par måneder siden efter ca. 30 års pause, intet andet end hvæse på alle frekvenser. Den forklaring jeg fik, var at en eller flere af "lytterne" var stået af, og når man ikke var i besiddelse af et diagram, var det for stor/dyr en opgave i forhold til radioens værdi.
Med venlig hilsen
Bent

Svar til #11:

Tag radioen med til en radioamatørklub - muligvis blot en korroderet/løs forbindelse?:

https://www.google.com/search?q=Sony+ICF-SW7600+ only+noise

fx:

Sony ICF SW7600 Multiband Radio Troubleshooting - med muzak :) :
https://www.youtube.com/watch?v=VCgEhgNg_u8

Her er en service manual til Sony ICF-SW7600GR:
https://www.radioamatore.info/attachments/articl e/1574/Sony_ICF-SW7600GR_service_manual. pdf
backup:
https://web.archive.org/web/20240722081456/https ://www.radioamatore.info/attachments/art icle/1574/Sony_ICF-SW7600GR_service_manu al.pdf

Ganske udemærket radio - når den virker:

Reviews For: Sony World Band Receiver ICF-SW7600GR:
https://www.eham.net/reviews/view-product?id=153 4

Mega Review: the Tecsun PL-880, PL-660, Sangean ATS-909X, and Sony ICF-SW7600GR go head-to-head:
https://swling.com/blog/tag/sony-icf-sw7600gr-re view/
Citat: "...
I have traveled extensively with the ’7600GR, however, as it has rock-solid, reliable performance; it’s my work horse and go-to radio for field recordings because I find its AGC and sync detector remain among the best in this class of radio. It also has a dedicated, stable line-out jack. Important controls are all accessible, and I can easily engage the key lock without fear of accidentally pressing the wrong button during the recording.
..."

Svar til #1: Jeg vil gå en lidt anden vej , med en Airspy SDR , som fylder nul og nix , feks HF+discovery. Du rejser sikkeret med en PC , men selv en android telefon vil fungere som bagsats.
god rejse-

Svar til #13:
Ja, den ser faktisk meget spændende ud.
Man har tilsyneladende også gjort noget som forbedrer mellembølge modtagelsen.

https://airspy.com/airspy-hf-discovery/

Gert / OZ4ZG

Svar til #12:
Hej Glenn
Jeg må nok tilstå, at "spilledåsen" er gået samme vej som andet elektronikaffald, iom et repværksted hævdede, at de ikke kunne gøre noget uden en vejledning.

til gengæld synes jeg, det er interessant, hvad du skriver om loop-antennerne. Det er nok på et lidt vel højt niveau for mig pt., men kan man uddrage en opskrift på en loop, der kunne bruges dels som fast antenne hjemme, samt som rejseantenne? (Jeg havde for nogle år siden kontakt med en radioamatør i Kirke Såby, tror jeg det var? Jeg mener at huske, at han jævnligt havde kontakt på HF med sin far i Sydafrika, med en loop, som endda ikke var monteret særligt højt oppe)

Hej Bent!
Synd du"bortskaffede" Sony'en. Man behøver ikke diagram for at skifte alle elektrolytter, de er faktisk alle mærket med værdi. Som jeg husker det, er der 15-16 lytter som er loddet på montage-siden, i Sony'en.
Der er faktisk rigtig mange, der er "genopstået".
Hvis andre ligger inde med den omtalte Sony, er det bare at komme igang.
OZ8OE

Svar til #7:

Hej
Med "kondensatordøden" menes der sandsynligvis at nogle SMD-
elektrolytter har lækket og måske har ødelagt / ætset nogle
printbaner
Det kan være næsten umuligt at lodde på dr steder hvor en
ætsning er værst

Mvh
Bjarne Olsen

Hej Bjarne!
Det er såmænd ganske almindelige kondensatorer, som man kender dem flest. Blot 10 mm høje. Der er ikke noget læk, de er blot tørret ud. Ingen beskadigede baner.
Ole

Svar til #1:

Har sendt dig en privat besked

M.v.h.
Christian

Svar til #15:

"til gengæld synes jeg, det er interessant, hvad du skriver om loop-antennerne. Det er nok på et lidt vel højt niveau for mig pt., men kan man uddrage en opskrift på en loop, der kunne bruges dels som fast antenne hjemme, samt som rejseantenne?"

Kig på denne loop-antenne:

Youloop Receiving Antenna:
https://www.wimo.com/en/youloop
Citat: "...
10 kHz - 30 MHz
..."

The Airspy Youloop is a freaking brilliant passive loop antenna:
https://swling.com/blog/2020/03/the-airspy-youlo op-is-a-freaking-brilliant-passive-loop- antenna/
Citat: "...
The Youloop is truly the travel antenna I’ve always wanted for portable SDR DXing. Here’s why:

It’s incredibly portable and can be rolled up to fit in a small travel pouch
It has all of the low-noise characteristics of other magnetic loop antennas
It’s wideband unlike many passive loop designs
It requires no variable capacitor or tuner
It’s made of quality components
It requires no external amplifier nor power source
It takes one minute to assemble
It’s affordable (~$35 USD shipped)

The only caveat? To take advantage of the Youloop, you must use a high dynamic range receiver.
..."

Lidt kritik:

YouLoop performance?:
https://forum.kiwisdr.com/index.php?p=/discussio n/2423/youloop-performance
Citat: "...
The Youloop by itself is not suitable for use with a KiWi SDR, as it does not have sufficient gain.
You could add a 20dB pre-amplifier, but to be honest IMHO the Youloop is a good example of marketing hype rather than sound technical performance.
In my experience, a normal single turn loop generally performs better.
backup:
https://web.archive.org/web/20230722130057/https ://g8jnj.net/moebius-loop-antenna
...
In all cases these small low gain broadband loops are really only suitable for use with low noise figure receivers for example the AirSpy HF+ and Discovery.
Otherwise it may also be necessary to add a broadband pre-amplifier in order to bring the weaker signals up to a more usable level.
..."

Martin g8jnj målinger. Det er lidt flueknepperi, da youloop kun er ca. 3..5 dB lavere:
https://web.archive.org/web/20230722130058im_/ht tps://mediaprocessor.websimages.com/widt h/544/crop/0%2C0%2C544x450/www.g8jnj.net /Loops%20at%201m%20spacing%206dB%20pad%2 0(corrected).png

YouLoop - is it worth buying?
https://forums.radioreference.com/threads/youloo p-is-it-worth-buying.479516/
backup:
https://web.archive.org/web/20241007175549/https ://forums.radioreference.com/threads/you loop-is-it-worth-buying.479516/
Citat: "...
This is a passive loop- meaning it has no amplifier. It's really intended for SDRs with hot front ends, It would fail miserably for portables and desktop radios without some amplification (note that I recall some desktops have a built in amp which you can switch in). If you need something that doesn't take up a lot of space in your shack and you're willing to experiment, this is a cheap way to go.
...
First off, the eBay one is slightly different than the one sold by Airspy and AirspyUS. I have both. The 2 black boxes are different in each model with the Airspy (non-eBay) working slightly better on lowest frequencies. These are only good as someone says with receivers with higher than normal gain. With that being said, I only recommend one if you are using an Airspy HF+ Discovery and then it is excellent. Otherwise, you might be wasting you money.
..."

Airspy YouLoop LF/MF/HF Möbius Receive Antenna:
https://www.hamradio.me/antennas/airspy-youloop- lf-mf-hf-mobius-receive-antenna.html
Citat: "...
Indoor YouLoop antenna reception tests
...
I put the YouLoop antenna assembly on a chair. I quickly noticed plenty of signals. The AM BCB was abundant of course, but also our local Culpeper NDB… and to my surprise WWVB. Loops are famous for their azimuth nulls so nulling the local NDB beacon was my first test.
...
I didn’t think this would be possible inside a home with myriad conductors about, but indeed it was quite apparent I could significantly null the NDB beacon along with other signals by turning the loop in my hand. I wasn’t expecting much of anything like this from my basement. [Bemærk: Basement betyder kælder]
...
Outdoor YouLoop antenna reception tests
...
Results are, in short, pretty darn impressive. The electrically small un-tuned loop antenna paired with the HF+ SDR at its feedpoint simply works.
...
Möbius vs conventional split loop
...
Key takeaways

All three sessions overlay quite nicely.
The Möbius crossover configuration provides a significant improvement in received power over the non-crossover up till about 1100 kHz.
Both approaches offer similar performance between 1100 and 1300 kHz.
The non-crossover configuration bests the Möbius crossover above 1300 kHz.
Regardless of these differences, both exhibit excellent broadband performance.
...
Works shockingly well indoors…
...
Considerations for any small loop antenna:

Ferrous materials should probably be kept well away.
As there is no escaping Chu-Wheeler limits, these antennas are very inefficient.
Thankfully inefficiency isn’t a show stopper for receiving purposes on the low bands.
..."

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Find evt andre opskrifter her:
https://wiki.radioreference.com/index.php/Loops# Make_Your_Own_YouLoop
backup:
https://web.archive.org/web/20241003191409/https ://wiki.radioreference.com/index.php/Loo ps#Make_Your_Own_YouLoop


Samme konstruktion som YouLoops:

DIY: How to build a Noise-Cancelling Passive Loop (NCPL) antenna:
https://swling.com/blog/2020/04/diy-how-to-build -a-noise-cancelling-passive-loop-ncpl-an tenna/
backup:
https://web.archive.org/web/20250207111253/https ://swling.com/blog/2020/04/diy-how-to-bu ild-a-noise-cancelling-passive-loop-ncpl -antenna/
Citat: "...
It works a treat. And, yes, folks…it’s fun to build.
...
What makes this loop so appealing (to me) is that it can be built with very few and common parts–indeed, many of us have all of the items in our junk boxes already. As the name implies, it is a passive design, so it requires no power source which is incredibly handy when you’re operating portable.
...
This is actually a very simple build––something even a beginner can do, as long as they’re okay with using a soldering iron. It does take patience preparing the loop cable properly.
..."

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Byg selv modtage bredbåndsloop med forstærker ned til 160 meter. Der skal anvendes andre ringkerner til mellembølge og langbølge:

A Wide Bandwidth Active Loop Receiving Antenna:
https://web.archive.org/web/20241005202616/https ://www.qsl.net/m0ayf/active-loop-receivi ng-antenna.html

Svar til #15:

"(Jeg havde for nogle år siden kontakt med en radioamatør i Kirke Såby, tror jeg det var? Jeg mener at huske, at han jævnligt havde kontakt på HF med sin far i Sydafrika, med en loop, som endda ikke var monteret særligt højt oppe)"

Loop-antenner til både sende og modtage behøver kun at være ca. 1-1,5 meter over jord. Loop-antennen ("ringen") skal være lodret. Grunden til, at den lodrette loop-antenne ikke mister energi til jorden er, at loop-antennen hovedsageligt laver magnetisk kobling til nærfeltet. Jorden kan ikke vekselvirke med RF-magnetfeltets nærfelt og jorden vil derfor ikke dæmpe RF-magnetfeltet nævneværdigt (medmindre der er større metalstykker i jorden "tæt" på loopen).

En ferritantenne er "blot" en lille afstemt modtage loop-antenne med en diameter på mellem 7-12mm.