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VK6BE > BEACON 03.12.03 11:06l 116 Lines 6504 Bytes #999 (0) @ WW
BID : E20132VK6BE
Read: DB0FHN GUEST
Subj: Re: History of the amateur beacon
Path: DB0FHN<DB0FOR<DB0MRW<DB0HOT<OK0PKL<OK0PPL<DB0RES<ON0AR<ZL2BAU<VK3AVE<
VK6HGR<VK6BBR<VK6RAW<VK6PBV<VK6JY
Sent: 031203/0303Z @:VK6JY.#ALY.#WA.AUS.OC #:23769 [Albany] FBB7 $:E20132VK6BE
From: VK6BE@VK6JY.#ALY.#WA.AUS.OC
To : BEACON@WW
Well, Andy, we had to build all our own gear, except that, in some cases,
ex Army gear could be adapted. My first 2 metre transceiver was a
disposals unit. Forget the number but it was something like AR301A. It had
a broad band IF (30 megs? - not sure now). It was said that with this gear
you didn't need to tune the band. You could hear any signal on 2 without
tuning the thing was so unselective!
My first 2 metre receiver was a home brew converter with an crystal
oscillator/tripler/doubler chain into an AMR300 receiver as a tunable IF
in the 7 meg region. Most of these converters being used by VK6 amateurs
were cascode as per the ARRL Handbook.
My transmitter was also crystal locked with an 8 MHz crystal
oscillator/tripler multiplied up to around 144.1. Everyone was crystal
locked on their own particular frequency, so we all called CQ and then
tuned the band for replies.
My transmitter was of a pattern used universally in this part of the
world. 6AC7 osc/tripler to 24 MHz, 6M5 doubler to 48 MHz and a 5763
tripler to 144 driving a 6146 which operated quite well at 144, at about
20 watts DC input. The antenna was a five over five stacked Yagi.
Modulation was AM, plate and screen modulated. I experimented a bit with
other types of modulation (modified Heising, clamp tube and NBFM - the
latter was the easiest to get going with only a mic, amplifier and an
ordinary RF amplifier tube modulating the Crystal). I tried other RF PAs
on 144 including the newly released EL34 which worked quite well and the
HK 257B which could be run at 100 watts, the legal maximum at that time.
Power supplies were lethal and extreme precautions had to be taken not to
get tangled with one. My low power stages on 144 ran from a 285 volt
supply and the PA from 500 volts. The HK257B ran from a supply of 1500
volts. The modulator supply was at 750 volts so you can see that you kept
one hand in your pocket when dealing with this gear.
On 50 MHz I ran similar receiving and transmitting gear but with a HK257B
running at 100 watts, later increased to 150 watts. This was an
interesting tube with a bright emitter, and an anode which heated up to
orange/yellow at full input. It worked well on full ratings to 120 MHz and
at reduced ratings much higher than that.These tubes were ex Dept of Civil
Aviation. They had been used in amplifiers in airport transmitters, but,
so I was told, the ventilation in the equipment was not sufficient and the
solder used to run out of the base pins, and the tube would fail through
losing contact with the base pins.They were sold off through diposals
shops at 10/- a time which was very cheap. It was simple to resolder the
base pins, and away they went.
I said power supplies were high voltage. I used 866A rectifiers which were
mercury vapour and glowed a beautiful purple under load. The heaters took
about 50 watts to operate but power supplies were no probalbe with
disposals gear cheap.I still have a number of these brand new in original
packets. Now they are useless!
I believe that the availability of relatively cheap black boxes has led to
the decline in the interest in amateur radio. There was a great deal of
interest 40 to 50 years ago in building your own gear, extra skills
required, and the hobby generated a lot of interest. That has all gone.
One further reminiscence. For several years I was President of the VK6
Division of the WIA and was also its Broadcast Officer. The Broadcast was
put out, as it still is, on 40 metres, AM in those days. The AM
transmitter was an AT 20 which was in two units weighing over half a ton,
and it sat along the wall in my shack which was at the end of the lounge
room. The AT20 had four 813s in the final modulated by 813s, a very hefty
PA tube, and on transmit the beast drew many amps from the 250 volt mains.
The broadcast commenced at 9.30 a.m. and we had to make sure that
breakfast was over before it began as to even turn on the toaster blew the
power fuses and I had to replace those before the broadcast could
continue.
There was difficulty with the broadcast in that 40 metres did not always
cover the whole region. 40 would do some fade outs. To accommodate the
country areas I built an audio distribution unit which plugged into
transmitters on 80 metres SSB (a Swan 350), and 50 MHz AM, transmitting
simultaneously. VK6BO the late Rolo picked up another transmission on 6
metre FM and put out an AM transmission on 144. BY this time the AT20 had
been replaced by a Geloso transmitter which we used on 40 metres.Later I
prerecorded the whole BC on a tape recorder and could sit back and watch
all those dials flickering up and down while the news went out. Strictly
speaking thie use of the recorder was not legal and nor was the
simultaneous transmission on several frequencies but the authorities did
not seem to worry about it and the system gave good coverage over the
southern part of the state.
Antennae were mostly home brew too. My yagis were built of electrical
conduit with copper wire on the second conductor on the folded dipole.
This arrangement made it easy to match 300 ohm open wire line which most
of us used. The lower HF bands had an 80 metre dipole (wire) with a pole
one end and a tree the other. The tre was a huge dead jarrah about 70 feet
high. I put a big stone in the bottom of a sock teied to fishing line and
threww it over a branch about 65 feet high. Good results from that
antenna!! I used home brew open wire line down to the shack and a parallel
tunign unit between the antenna and the transmitter. Until the Swan 350
and similar equipment came out we used separate transmitter and receiver
with a switch to put on the low power stages of the transmitter so that we
could net it to the receiver.
My location at this time was superb - 1000 feet above sea level with a
terrific outlook on all sides except to the south east. I held scheds on
144 and 50 with an amateur in Geraldton, a sea port to the north and about
500 km away. I could work him 59 each way when the boys in Perth only 25
km from me could only get a heterodyne.
If this bores you fellers, don't tell me; just delete it!
Cheers,
Bob VK6BE.
>
> More memories of your the VHFing in the past would go down well this side
> of the world Bob. Some of us grew up with ready availablity of commercial
> VHF/UHF gear. I find hearing how people did it when you couldn't pop out
> and buy a quad band handy fascinating.
> 73 de Andy GM7HUD
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