LM3886 for lower bands

DIY audio fanatics appreciate this ‘chipamp’ a lot. See for example https://audio-creative.nl/audio-creative/diy-lm3886-chipamp/

                                 LM3886 as 65 Watt audio amplifier

It provides 65 Watts audio into 8 ohms. Audio quality is more than all right. PCB’s with this chip are available for about 10 euro’s (eBay, Aliexpress). 

Bunch of low-cost LM3886 PCB's (10 euro each)

The frequency response curve shows that we are dealing with a broadband amplifier. @ 200 kHz the attenuation is only 1.7 dB !

Frequency response

Therefore, this chip should be able to be used as an RF amplifier for the 2200 m band (135.7 – 137.8 kHz) and lower bands.

A challenge for the designer is of course to adapt the 8 ohms output to the antenna impedance.

Teylers museum

Some collections are special and deserve to be maintained. 

The collection of Mr. Teyler from Haarlem is such a special collection. This week we visited the Teylers museum and were able to see interesting items such as Leyden jars, 19th century light bulbs, ancient skeletons and the study room of prof. Lorentz.

More info:  https://www.teylersmuseum.nl/nl

Leyden jars

Oval room

Collection 19th century light bulbs

Paint art

Neanderthalers' jaw

uBITX kit available

A DIY kit for the HF general coverage transceiver uBITX is available:

http://www.hfsignals.com/

Off topic:

                                              'Waterbus', view from Zwijndrecht

73 from Banja Luka

A nice eQSL-card was found in the eqsl.cc postbox today.
An SSB 6m QSO made August 2008 was confirmed by Vlado from Bosnia Herzegovina:

Off topic:

                                                                  Dordrecht

Medium Wave receiver

This is how a Japanese design of a Medium Wave receiver looks like:

And this is how it looks like as a $5 DIY kit:

https://www.banggood.com/AM-Radio-DIY-Electronic-Kit-Learning-Suite-p-1017328.html?rmmds=mywishlist

Off topic:

Suriname river, Paramaribo 2018 

Satellite TV

Today I kept track of the signal strength of the satellite TV signal from the satellite Astra 23.5 (Astra 3B transmits just above 11 GHz).

It was interesting to see that a dip in the signal strength came with the bad weather that arrived from the North Sea;

Presentation of rainfall App 'buienradar'

TV screen with sat parameters

KiCad

I downloaded KiCad version 4.0.7 which is an open source Electronics Design program. With the schematic editor you can create your design without limit; there are no paywalls to unlock features. An official library for schematic symbols and a built-in schematic symbol editor are available.More info here: http://kicad-pcb.org/

The first schematic with this program:

Off topic:

Paramaribo January 12, 2018

Twin diode receiver

This radio uses two receiver chains; the supply voltage needed for the transistor amplifier is generated by a strong local broadcast station to which diode receiver number 1 (left side of the schematic) is fix-tuned. Tune with the aid of a meter and adjust for maximum detection. Low-level stations are detected with the diode receiver number two (right side of schematic). Use a germanium low signal AF type transistor (AC151, 2SB187) and Ge-diodes (AA119, AA112, AO85...). Design coil1 and 2 in such a way that Medium Wave broadcast stations are received.

A supply voltage as low as 450 mV produces audible signal amplification. Of course you have to use TWO antennas.
The designer of this radio uses for receiver number 2 (right) a loop (frame) antenna, for receiver number 1 (left) a a 20 meters outside antenna (wire). 

Receiver 1 generates a supply voltage of approx. 900 mV under load of receiver number 2.
Adjust the variable 250 kOhms resistor to approx 50 % of the voltage generated by receiver number 1 voltage (measured at + pole). Best value for 10 kOhms trim pot is 3 to 6 kOhms.

Do not use electrolytic capacitors for the 0.1 uF capacitors. Do not forget to install the 1 nF capacitor. Attention for the polarity of the diode (AA112, AO85, AA119...) in receiver nr 1.

Source:
http://pe2bz.philpem.me.uk/Comm/-%20Receivers/-%20Crystal/Prj-058-WithAF-Amp/dt.htm

Off topic:

Canal in Den Haag (Zuidwal / Dunne Bierkade), 7 Sep.  2017

QRP labs 5W CW transceiver kit

Hans Summers, G0UPL, has developped a new transceiver:
It is a mono-band 5W CW transceiver, with tons of features, including WSPR beacon, built-in alignment/test equipment, iambic keyer, CW decoder, rotary-encoder tuned synthesised VFO, and more. Price is appr. 42€. The kit is available for 80, 60, 40, 30, 20 or 17m bands and can be ordered here:https://shop.qrp-labs.com/qcx .
The 137-page assembly/operation manual can be downloaded here http://qrp-labs.com/qcx and includes circuit diagram and comprehensive description of circuit operation.

The transceiver has lots of nice features:

+ Easy to build, single-board design, 10 x 8cm, all controls are board-mounted
+ Professional quality double-sided, through-hole plated, silk-screen printed PCB
+ Choice of single band, 80, 60, 40, 30, 20 or 17m
+ Approximately 3-5W CW output (depending on supply voltage)
+ 7-16V recommended supply voltage
+ etc. etc.

Off topic: Vintage cars on Goeree-Overflakkee

Citroen HY in Oude Tonge

Truck in Achthuizen

Used car in Greece, Epirus (holiday 2013)

Radio Veronica

Radio Veronica was an offshore radio station that began broadcasting in 1960. The station transmitted from the North Sea for over fourteen years. It was set up by independent radio, TV and household electrical retailers in the Netherlands to stimulate the sales of radio receivers by providing an alternative to the Netherlands state-licensed stations in Hilversum.

It must have been around 1973 that I could receive Radio Veronica with a diode receiver (similar to the 'jampot' receiver below) from the middle of the Netherlands. I had to use a 20 meter longwire antenna to listen to  Radio Veronica.

Broadcasts began on 21 April 1960. 
Used medium wave frequencies were 1562 kHz (192 meter) and 557 kHz (538 meter). 
The station announced itself as VRON (Vrije Radio Omroep Nederland; Free Radio Station [of the] Netherlands) but changed to Radio Veronica, after the poem "Het Zwarte Schaap Veronica" — The Black Sheep Veronica — by the children's poet Annie M.G. Schmidt.

The station's closure, some of its staff applied for a broadcasting licence and continued as a legal organisation with the same name. The original Radio Veronica became the most popular station in the Netherlands. It broadcast from a former lightship Borkum Riff and anchored off the Dutch coastline. 

The ship was fitted with a horizontal Medium Wave antenna between the fore and aft masts, fed by a one-kilowatt transmitter. Most of its programs were recorded in a studio in Hilversum. At the end of the 1960s the studios and offices moved to bigger premises in Hilversum. Initially advertisers were reluctant to buy airtime, but those that did reported increases in sales and gradually the station's revenue improved.

For a short time the station also ran an English language service under the call letters CNBC (Commercial Neutral Broadcasting Company). Although short-lived, CNBC was presented by professional broadcasters who were able to give invaluable technical advice to Veronica's Dutch staff.

Update 15-JAN-2021

On  https://192tv.tv/ you can watch/listen the old radio/videoclips from Radio Veronica.