[BC] HF &more

[Rob Atkinson]

Clive; thanks much for the description--it is much easier to visualize now.

I know Andrew makes 25 kw LPs--I would not be surprised if they had made 100 
kw as a custom job.

Rob Atkinson


From: "Clive Warner" <clive at citiria.com>
Reply-To: Broadcast Radio Mailing List <broadcast at radiolists.net>
To: <broadcast at radiolists.net>
Subject: [BC] HF &more
Date: Sun, 24 Jul 2005 11:51:53 -0500

 > good heavens, i wonder what on earth a 100 kw ferrite balun looks like?
 >
 > rob atkinson

- Looks like a miniature version of a HV transformer, except the casing is
aluminium and the cooling tubes replaced by heat-dissipation fins. Size,
about 2 metres cube. Can't recall the efficiency but they are quite good.
I do have a photo of me measuring the input Z into the balun. Unfortunately
I haven't scanned the Niger photos yet.

In that particular case the distance of the open feeders was considerable.
We installed a new 100KW log-aperiodic HF array, from - - darn it I can't
recall, would it be Andrews? And that came in at an excellent VSWR right
across 6 - 26, but I had to do a little matching work on the original
antennas which were slung between wooden poles. Think I used a delta match
on one section, stubs on others.

This was the same site we (Incomtel, a no-longer-extant UK installations
company) installed a Telefunken PDM on medium wave. Ah, now I remember why I
have so few photos, the bloody military guards at the station took my camera
away despite the fact I was the person installing all the kit! The people
were so poor that if you put a tool on the floor for a moment while working,
while you turned your back someone would thieve it.

I still have many many photos to scan, it takes so long especially the
Photoshop work to clean them up. One of the most interesting is the 20KW
mobile AM studio/transmitter/genny/antenna rigs built for clandestine work!
We made two complete units.
Clive


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