Date: Fri, 06 Jul 2001 02:57:45 -0700 (PDT)
From: "John Sexton" <computernetworks@go.com>
Subject: Re: LF: The Other Man
To: rsgb_lf_group@blacksheep.org
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Hi Steve, Hi Vic,
I looked through my list of stations and found that I have heard Vic at least once, so you are at least getting as far as Reading. Unfortunately I don't have a record of the date nor signal strength, but will listen out again and report when I hear something.
Your situation sounds very similar to mine, with big trees that tend to absorb everything.
My first receiver was also a Super Regen, which worked very well, but bears no comparison with the AOR 7030 that I subsequently purchased. The main problems were accuracy, bandwidth and knowing exactly where you were listening. I still use it occasionally with a second antenna for dual frequency monitoring, so don't scrap it.
Good luck with Dx and I shall be listening out for the call sign.
73, John, G4CNN

-----Original Message-----
From: "Steve Rawlings"<steve@alg.demon.co.uk>
To: "LF Group"<rsgb_lf_group@blacksheep.org>
Date: Thu Jul 05 10:26:50 PDT 2001
Subject: LF: The Other Man's Station: G8IK

>Hi All,>
>Vic G8IK, located in Solihull, Birmingham, has been kind enough
>to write a personal account describing his first 2 years on LF. 
>Vic writes:
>
>Initial 73 kHz tests
>--------------------
>Seeking fresh fields, and pastures new, I thought I'd have a go
>at 73 - not very optimistic but I thought maybe someone else in
>this region might be similarly motivated.  Luckily I had just
>purchased some coils at a rally and had sufficient for a simple
>receiver.  I used FETs in three RF stages followed by a voltage
>doubling detector with regeneration to improve selectivity, then
>the usual audio stages.  The coils were single windings with no
>coupling coils, so I used resistance capacity coupling between
>stages with very small coupling capacities to minimise damping of
>the tuned circuits.  I have a number of accurate oscillators
>which, with Rugby, helped me to find the band.  The receiver
>worked well, with plenty of gain and selectivity.
>
>For the rig, I used a small ferrite rod antenna, with a BC108 as
>oscillator tuned to the band with two 2000 pF compression
>trimmers, which drove two TIP126s in parallel.  Using an 80 ohm
>power meter as load, these delivered 30 watts or more at 350 mA 
>80 v.  In spite of a reasonable heatsink they overheated after a
>few minutes, so I made a multi-vibrator with an on-off ratio of
>1:1, driving an on-off relay which enabled the rig to run for
>long periods.  I wound a 2.5 litre drum full of 22 SWG wire (with
>taps) and, with the present antenna extended to about 170 ft
>(twice its present length), this resonated somewhere near the
>band.  I had a variometer (a museum piece) which proved excellent
>for fine tuning.  With everything in order, I switched the gear
>on and made my way, with the receiver, to a colleague who has a
>substantial antenna and who lives about a mile away, hoping that
>the signal would travel at least this distance, but no - not a
>trace!
>
>Success on 136 kHz
>------------------
>136, I thought, offered more promise as the antenna would be
>effectively twice as high and twice as long.   I retuned the gear
>to the new band and, to my delight, had a reply to my first CQ
>call: only seven miles away (G3YXM) but it was a start, and, to
>my amazement, this was followed by reports from G4GVC and GW4ALG.
>
>Thus encouraged, I decided to build a 200 watt rig - I had the
>main ingredients: two high voltage transformers, a 50 watt
>tetrode and two high voltage variable capacitors (45 pF
>Eddystone, ca 1935).  I assembled all this on a 3 ft  x  1 ft
>board with a hardboard panel of similar size, using the existing
>rig (down-powered) as the driver.  My main problem was getting
>the right L/C ratio for the anode coil and, at the same time,
>allowing for the two variable capacitors (in parallel) to give
>some degree of tuning.  I partly solved this by tapping the anode
>half-way down the coil (a 2.5 litre drum two thirds full of 22
>SWG) and using rather less than the optimum tuning capacity (700
>pF instead of 800-1000 pF).  I wound a coupling coil at the cold
>end of the coil, and was ready to go.  I'd arranged the power
>supplies to give me 500, 1000, or with the two in series, 1500
>volts, and with full power almost burnt out two one-hundred watt
>lamps!  Before going on the air, I was concerned about that L/C
>ratio, so I had a look at the waveform - it was dreadful - I
>visualised strings of harmonics every 136 kHz well into the HF
>region.  I amended matters by reducing the grid drive from about
>8 to 2 mA (with only a slight loss of efficiency), and included a
>low pass filter in the output.
>
>I was now up and running, but at this stage the lack of
>'operateability' of the receiver became a problem - I had to
>jiggle two RF tuning controls; regeneration; and BFO, so decided
>to build a superhet.  I used 2 MHz for the IF (for which I could
>wind coils) with a simple bridge circuit for the crystal filter
>in which the capacity of the crystal (plus holder) is balanced by
>a variable 'phasing' capacitor - which gives wide control of
>selectivity: at exact balance, it was extremely sharp.
>
>The receiver works well and I have no trouble 'winkling' out the
>DX, but have been disappointed in not being able to work outside
>the British Isles.  I have hopes, next autumn, of making
>improvements to the antenna, at present only 80 ft long and
>barely 20 ft high.  I have some tall trees at the bottom of the
>garden which either must go, or else serve as supports for the
>end of the antenna (I am thinking an archer might help!).
>
>Vic Morse, G8IK
>


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