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Problems On Shortwave In Brazil

SomeRadioGuy

SomeRadioGuy

They're operating at 50kw instead of the usual 100kw.

They have new tubes on order and hope to be back operating normally in about a week or so.

Paul
 
Haven’t heard anything further about implementing DRM on shortwave in Brazil, following the tests of a few years ago. The transmitter manufacturer for those apparently dropped shortwave from its product offerings.
 
Even though most won't notice, 11780 Brazil is still operating at half power of 50KW ... they got new tube but they were no good so the old one back in operation right now. They've been operating this way for a month.

Im not a math guy, but someone told me its only 3db difference between 100kw and 50kw.. i've noticed almost no difference up here.
 
I'd suppose that being in the 25 meter band, they can get out pretty far with fairly little power if the conditions are right, but I'm not an expert.

c
 
cc333 said:
I'd suppose that being in the 25 meter band, they can get out pretty far with fairly little power if the conditions are right, but I'm not an expert.
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In 1966 I bought an AM and SW combo to move from San Pedro de Amaguaña to Quito, Ecuador. The SW was about 300 watts or so into a longwire in the 3.3 MHz tropical band. When we cleared out the old offices, I found a file drawer at least half filled with reports of reception from Australia, New Zealand, Korea, Europe, Scandinavia and North America.

High power means much more consistent good reception, every day, all year long. Low power meant that sometime you could be heard all over the world, and sometimes not even a few hundred miles away.
 
300 watts and a simple antenna in the 90 meter band (as well as the nearby ham bands) will go world-wide if conditions are right, especially during the winter at night. Good enough at the sunspot peak, like now, but even better when the sunspots are at the minimum, which will be in another 4-6 years.

The difference between 50 and 100 kW watts on 25 meters when the sunspots are at the max is negligible.
 
SomeRadioGuy said:
Even though most won't notice, 11780 Brazil is still operating at half power of 50KW ... they got new tube but they were no good so the old one back in operation right now. They've been operating this way for a month.
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The problem with old shortwave transmitters is that quality replacement tubes are very rare and extremely expensive.

I have read that some broadcasters try to save money by ordering cheaper tubes from China, but discover they are of poor quality. Perhaps that’s what happened with the EBC operation in Brazil.
 
Mediafrog+ said:
The problem with old shortwave transmitters is that quality replacement tubes are very rare and extremely expensive.

I have read that some broadcasters try to save money by ordering cheaper tubes from China, but discover they are of poor quality. Perhaps that’s what happened with the EBC operation in Brazil.
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The radio engineering director told me they had a source in Brazil
 
cc333 said:
Are new tubes (regardless of quality) still being produced for those transmitters, or are they all NOS?

c
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No idea. I do know they are 4cx5000s
 
SomeRadioGuy said:
The radio engineering director told me they had a source in Brazil
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Brazil, for decades, has manufactured most of its transmitters and studio gear and a good percentage of components. It's a big country with lots of radio stations. The Brazilian transmitter manufacturers also tried to get sales in the rest of South America with some success.

I know that for a while they made vacuum tubes there, but I doubt there was enough market for the kind that 100 kw transmitters use.
 
davideduardo said:
.I know that for a while they made vacuum tubes there, but I doubt there was enough market for the kind that 100 kw transmitters use.
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The EBC shortwave transmitters are actually 250kw units that recently have been running at reduced power, perhaps to trim operational costs and extend the life of those tubes.
 
Mediafrog+ said:
The EBC shortwave transmitters are actually 250kw units that recently have been running at reduced power, perhaps to trim operational costs and extend the life of those tubes.
Click to expand...

Theyve run at 100kw for at least the last 5-6 years........
 


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