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 Anyone on the forum running shortwave transmitters, may be interested
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 Return to top of page · Post #: 1 · Written at 12:37:47 PM on 9 July 2018.
Flukeoneseventyfive's Gravatar
 Location: Laidley, QLD
 Member since 16 September 2015
 Member #: 1799
 Postcount: 109

G'Day Folks.
I did see a while back on the forum, a few people running transmitters on shortwave.
I found these this morning.

https://www.ebay.com.au/itm/Six-x-H1141-Marconi-HF-10kW-Transmitters-complete-with-Eight-x/132686554481?hash=item1ee4bc2571:g:rH0AAOSwCvhbOeB~

10kW is a tad over the 400 watts allowed with my amateur ticket.
I suspect the digital driver units would exceed that as well.

Cheers.


 
 Return to top of page · Post #: 2 · Written at 2:56:36 PM on 9 July 2018.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1906

Nice!


 
 Return to top of page · Post #: 3 · Written at 5:19:06 PM on 9 July 2018.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6349

At that power output you'd also want to be sure you wouldn't get microwaved by the radiation from the tuned circuit too. At full power, you'd also want some sponsors to help pay the electric bill.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 4 · Written at 6:36:48 PM on 9 July 2018.
Relayautomatic's avatar
 Location: Canberra, ACT
 Member since 24 April 2012
 Member #: 1136
 Postcount: 122

They would do nicely for a linear amp. Of course matching the antenna would be important to get the maximum output.


 
 Return to top of page · Post #: 5 · Written at 10:24:11 PM on 9 July 2018.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6012

If this were in the USA, they would be snapped up by the idiots who infest CB Channel 6 (aka the Superbowl).


 
 Return to top of page · Post #: 6 · Written at 2:37:09 PM on 10 July 2018.
Flukeoneseventyfive's Gravatar
 Location: Laidley, QLD
 Member since 16 September 2015
 Member #: 1799
 Postcount: 109

I was thinking of people that run Ozy radio and 4KZ on 5MHz and similar stations around the country.

Would be an ideal purchase for them.

I prefer to be running QRP (low power) on HF, around 5 mW to 5 watts is all that is needed for good digital contacts these days, the new digital modes that keep coming out, are getting so good at working with low signal levels.

I left a receiver running and reporting back to a web site, I had received over fifty countries in a week, this was on 40 metres (7.070 MHz)
When people were complaining about how poor the conditions were for radio contacts..

They would be nice to have.
Then it's the issue of getting 3 phase power connected, setting them up, getting the towers and the required coax to supply the signals to the log-periodic antennas and I suppose they may be water cooled, so another thing to sort.
Oh and a couple of extra jobs, so I can support paying for the power bill.


 
 Return to top of page · Post #: 7 · Written at 7:49:45 PM on 10 July 2018.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 240

The output valves (as shown on the site) are air-cooled, so a forced-air setup would need to be installed. (No need for water cooling)

However, a more serious problem may occur if one of the big bottles are cracked. These babies are loaded with beryllium oxide.
I noticed one heaped on top of a rack---you really don't want to breath in any dust from a cracked bottle.

Another observation, there were two bids for around six hundred bucks. By the look of those inductors/transformers I would
imagine one could add a grand or more for freight.

It would seem somebody (or somebodies) desperately wants this gear.

But back to your statement "------5mW to 5W -------" that's pretty impressive for HF work Fluke. I have heard of operators working DX on
a Watt (single valve CW Morse).

Are you talking DX on 5mW??? Very interested for more info.

Cheers,

G.


 
 Return to top of page · Post #: 8 · Written at 10:01:47 AM on 11 July 2018.
Flukeoneseventyfive's Gravatar
 Location: Laidley, QLD
 Member since 16 September 2015
 Member #: 1799
 Postcount: 109

G'Day BBTV .
yes I have had 4cx250's and sockets that were suspect of having beryllium oxide.

for the QRP contacts.
I was using JT65-HF and many other modes such as WSPR.
Propagation, is following the grey line and was from the Caribbean heading west across the US and through the pacific.
had many contacts, this was on 40 meters, I used a German kit transceive,r a FA-SDR, software defined using software to drive it.
I just looked at the spec's for the transmitter, and it is 10mW into the 1watt amp, but I had bypassed the 1 watt amp.
This was into a vertical antenna for 40 meters fed with about 15 or so meters of CNT-400 coax.
and the digital modes get through were CW won't, you can't hear most of the signals, they are in the noise around -10 and -18dB below.
I can see the signals in the FFT waterfall display.
For CW you need to hear the signal to decode it.

That was a brilliant antenna, it was damaged by the builders, when they dug out the for the footings where the shed was built.
I had the antenna laying down on the roof, as I had to move my tower and large 5 element tri-band yagi's, they bent the antenna with the machinery, it is in a u shape, will repair it one day.
same people dug through my phone line, I used some cable location gear from work to show were and how deep the cable was and they still dug through it. I had to dig the rest of the cable up to get a quick extension run around the area.
What fun. ...


 
 Return to top of page · Post #: 9 · Written at 10:56:47 AM on 11 July 2018.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 240

From the Caribbean west towards the US then onward to the Pacific------Excellent effort, especially with the PA by-passed.

It sounds like your antenna had a lot to do with those stunning results, I hope you get it up and running again soon.

With regards to digging up phone lines; One sure way to have any underground cables severed is to supply the backhoe operator with
precise position and depth charts. They will find them every time, just ask Telstra.

I have a theory that these guys harbour a deep mistrust for any conveyor of charge carriers. They feel an urge to destroy such devices,
probably a deep-rooted superstition from past lives perhaps?

I wouldn't mind a picture of your antenna sometime after you rebuild it.

Cheers,

G.


 
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