There are two100 Ohm inputs.Both have 10 kOhm to GND. The two inputs go
to two W81 RF tubes. Both tubes have a 100 pF cap in series with the grid
and 1MOhm + 100k pot to cathode. Two switches can connect a LC network from
input to GND (ferrite coils), they are probably kind of antenna tuning.
Inge
On 28 February 2011 15:32, Stadem, Richard D. <[log in to unmask]> wrote:
> Whatever antenna is used needs to be matched up to the receiver with the
> appropriate jack or connector to get the appropriate impedance match. Inge,
> can you describe the antenna input terminals on your receiver?
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Ahne Oosterhof
> Sent: Sunday, February 27, 2011 1:02 PM
> To: [log in to unmask]
> Subject: Re: [TN] NTC: GEC BRT 400S
>
> I searched BING for "+Antenna +lf" and found small ready made antennas
> covering the band you mentioned for less than $200 and some descriptions of
> antennas like those on your ship.
> No idea regarding which is best or even acceptably useful.
>
> Have fun,
> Ahne.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
> Sent: Sunday, February 27, 2011 10:38
> To: [log in to unmask]
> Subject: Re: [TN] NTC: GEC BRT 400S
>
> Thanks, Steve & Blair,
>
> the manual is excellent, thanks again. Unfortunately very little about
> antennas.
> When I look through the 56 ps manual, I realize this is a very advanced
> machine for its age. They are said to be one of the best for that time.
> Just
> wonder what they cost then? Nothing for the picnic, weight 75 pounds!
>
> A funny problem: it's almost impossible to get the old copper lines with
> porcelain isolators. Whoever I try look at me as being a Neanderthaler. So,
> seems as it will be a variable dipol of some kind. From what you say,
> Blair,
> it will be little of a monster to cover all bands. On the other hand, is
> there anything today at kHz bands? Beacons? Navigation buoys? Radio sonds?
> I
> guess my old receiver will be laughed at by the VHF/UHF/GHZ radios: " Have
> you seen, folks, a GEC BRT 400S...ho-ho-ho..it smells of stinky selenium
> rectifier and leaking electrolytes. Poor thing, got a frequency range like
> an elephant..ho-ho....use capacitors with blades and gear boxes..no, no,
> not
> kidding....and you should see the line transformer...my...weight as a six
> feet man...guys...let's help him back to the museum.."
>
> Inge
>
> On 27 February 2011 17:19, Steve Gregory
> <[log in to unmask]>wrote:
>
> > Hi Inge!
> >
> > Haven't heard from you in quite sometime! Glad to hear from you! I have
> > your pictures posted:
> >
> > http://stevezeva.homestead.com/Inge_s_Lab.jpg
> >
> > You have a nice little lab to work in! Here's your receiver:
> >
> > http://stevezeva.homestead.com/Inge_s_BRT400.jpg
> >
> > I know nothing about antennas, but I did find this. I don't know if you
> > have a manual for your receiver, but here's one for download:
> >
> > http://bama.edebris.com/manuals/ge/brt400
> >
> > But before you can see it, you will have to download this viewer:
> >
> > http://windjview.sourceforge.net/
> >
> > It's almost like an Adobe *.pdf viewer
> >
> > In the manual, it does talk about antennas (they are called aerials in
> the
> > manual) on page 20 and 21.
> >
> > Steve
> >
> > -----Original Message----- From: Blair Hogg
> > Sent: Sunday, February 27, 2011 10:46 AM
> > To: [log in to unmask]
> > Subject: Re: [TN] NTC: GEC BRT 400S
> >
> >
> > Inge,
> >
> > I'll wait for the photos, but an antenna is an antenna. It can either be
> > resonant at a particular frequency or tuned by an antenna tuner as
> needed.
> > Probably for a wide coverage receiver a long wire antenna is the easiest
> > place to start. The longer the better, up to a certain point.
> >
> > If you are interested in a particular band of frequencies, a dipole works
> > well, but tends to be directional - not necessarily a bad thing.
> >
> > For 28 MHz I've used dipoles that are roughly 5.8 meters on each leg. The
> > length varies inversely with the frequency, so at 3 MHz the dipole would
> > need to be 58 meters or so. But any piece of wire will work, some will
> work
> > better than others.
> >
> > Once I see the photo I'll refine my comments.
> >
> > Blair
> >
> > On Sun, 27 Feb 2011 14:57:42 +0100, Inge Hernefjord <
> > [log in to unmask]>
> > wrote:
> >
> > Hi, when I left the navy decades ago, I missed my radio equipments.
> >> However,
> >> I succeded to save one traffic receiver as you can see on the photo (if
> >> Steve can give a hand). This machine is of course stonaged and
> hopelessly
> >> behind technology of today, but of nostalgic reasons I would like to
> give
> >> it
> >> a try. I've spent some money for service and now the receiver can work.
> >>
> >> Now, I've little knowhow about aerial antennas for 380 Kc/s to 30 Mc/s.
> I
> >> remember I had a network of copper lines across the destroyer, but know
> >> nothing of the design.( Had to be repaired frequently after shooting
> with
> >> the anti-aircraft artillery).
> >>
> >> So, to the question: Anyone familiar with the GEC 400S? How would a
> modern
> >> antenna look like and what kind of tuning and compensation is necessary
> ?
> >> I've contacted some DX guys, but they know nothing about this antiquity.
> >>
> >> Wait for the photos.
> >>
> >> Inge
> >>
> >>
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