SPECTRUM COMMUNICATIONS

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News & New Products - 26 January 2020

Proprietors;- Mr A.J. Nailer HNC BA G4CFY, Mrs J.R. Nailer. 

12 WEATHERBURY WAY, DORCHESTER, DORSET, DT1 2EF, ENGLAND

Phone UK 01305 262250 International 0044 1305 262250

Please email or phone for a quote or for a Paypal money request or for bank details. Payment can be by direct bank transfer or by credit/debit card or via Paypal to g4cfy@talktalk.net together with a note stating product required. Purchase of several items is likely to make a saving on postage. You can also obtain products by using my Ebay shop https://ebay.co.uk/str/Spectrum-Comms and pay via Paypal.

Orders & quote requests to  jean@spectrumcomms.co.uk

Technical queries to  g4cfy@talktalk.net 

NEWS & PRODUCT UPDATE 26 January 2020.  

The new range of high stability, low temperature coefficient 10mm coils suitable for oscillators are now available.  See details on the Components pages.

A New Intermediate Licence Crystal Oscillator with low pass filter is newly introduced to satisfy the requirements of the Intermediate Licence qualification.  It is available through our Ebay shop with code number 2837 2826 1711 (entered without the gaps).  This in conjunction with the Int. Lic. VFO allows oscillator alignment, comparison of stability of crystal and variable oscillators and the effect of adding a low pass filter to remove oscillator harmonics.

The original stable Portland VFO that included the tuning potentiometer in the box has been put into a new box that with a twisted triple of wires connects to the tuning potentiometer. This now means the pot can be fixed to the front panel and the oscillator box can be fixed to the chassis of the equipment. It is on our Ebay shop as 2837 3120 1669 (put in without the gaps).

A new modular receiver project has been introduced to replace the archived Classic 80 & 20 metre SSB Receiver. The modules are:-

Item  Description Ebay number
1   80 & 20m Bandpass filters & RX Mixer   2837 2629 1649
2   6 pole Ladder SSB 9MHz Filter   2833 2185 6925
3   9MHz 90dB gain IF Amplifier with AGC   2837 2819 5874
4   SSB Product Detector & Dual Carrier Osc   2833 5988 1384
5   Audio 1W Amplifier 36dB Gain   2837 2603 9697
6   Portland VFO 5.0-5.5MHz   2837 3120 1669

The Super Sudden Receiver project by Tex Swann G3TEX and featured in the winter edition of the GQRP Sprat Magazine is now available as a Spectrum kit (with the co-operation and approval of Tex) and is on Ebay with reference 2837 2688 1674.

Over the Christmas  & New Year period the bulk of active product data has been reworked with new header and with drawing now converted to PNG format and integrated into the WORD file so all are available in electronic form and are not created by literally pasting a correct sized circuit or picture on the text document.

Complete recreation of all product and parts lists has also been done together with re-pricing everything to incorporate present parts costs.  All Spectrum products on the Ebay Shop have been edited and updated and can be accessed on https://ebay.co.uk/str/Spectrum-Comms Some products that haven't sold in the last 3 months have been removed and the new ones mentioned above have been added.  The total number of products there is 156 as of 25 January 2020. 

Work on re-writing Technical for the Terrified Book II into Understanding Radio Book 2 is progressing again now that bulk of updating product data has been completed. Chapters 1-6 & 10 are now print ready.  About another 13 to do.

Understanding Radio Book 2 will comprise the following chapters, Passive Components, old & New; AC & DC Equivalent Circuits; Oscillators, Variable & Crystal; Feedback and Amplifier Stability; Active Audio Low Pass Filters; Singly Balanced Mixers; Laying out Printed Circuit boards; Measurements and Test Jigs; Simple Receivers for 100kHz-30MHz; Superhet Receivers; RF, IF, and LO in superhet Receivers; Circuit Matching with Pi & T networks; Coax, wide and narrow Twin Feeders; RF Power, SWR, and the noise Bridge; Antennas, Gain & Bandwidth; Antenna Tuning Units for TX & RX; Antenna Advice for the Radio Listener; Interference to Broadcast Radio & TV.

Earlier this year the 118-400MHz Preamplifier underwent further development with a sharper low pass filter at the top of the band rolling off at 400MHz so the gain at 500MHz passes through 0dB while the high pass filter now is -3dB relative to maximum gain at 110MHz. Typical mid range gain is 18dB and the stopband is -25dB from 600-1000MHz.    IT is now sold as 110-400MHz RX Preamp PP3 and 110-400MHz RX Preamp Mains, both with an 0.6m BNC-BNC or BNC-PL259 lead. See the Scanner & Listener page.

The Morse Oscillator has now had the digital keying input removed as no-one used it.  Also the 3.5mm jack socket for the key has been replaced with a good old 1/4" jack socket, to suit the plug that most people have on their Morse keys.   The Ext Sp jack has now been re-designated as Phones as no-one needs an extension speaker anyway, and most want to use phones to reduce the audio nuisance to those not interested in bleep bleep.  This has caused a little problem though as most modern miniature headsets are designed for stereo and when plugged into the mono jack only one earpiece works.  I can supply the kit or built unit with a stereo jack socket which can be wired so both earpieces work.

The RX SPC ATU and QRP TX SPC ATU both now have a pretty new facia label that makes them look even better.  The circuitry inside is the same and this label makes the product a little cheaper because of the time saved on the time spent adding decals from a label maker onto the panel and getting them lined up.  I need to do the same with the HF Tuneable Preamp and HF Switched Preamp now because they have a lot more individual labels to get placed correctly and that takes about 20 minutes to get right.

G4CFY 4 Band Regen Receiver  This is a further development of the single band G3RJV/G4CFY Regen Receiver with optimization of the oscillator section of the receiver to cover the bands carrying the maximum number of SW broadcast and Amateur Radio traffic.  These are 1.8-3.25MHz, 3.25-5.85MHz, 5.85-10.53MHz, and 10.53-18.95MHz.  This is achieved by removing the coil from the Single Band Regen receiver board and using an additional coil pack board.  To achieve the best operation over this total range it was necessary to also change the values of C3 and C5 of the single band version. 4 Band Regen Receiver Kit excluding the knob 36.50  UK, 42.00 EU, 43.50 World.  

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Spectrum Communications was established as a part-time business by Tony Nailer G4CFY in October 1978.  In August 1981 following the legalization of CB in the UK there was sufficient work and CB sales for both Tony & wife Jean for full time employment.  CB popularity declined steadily to a very low level by about 2000 and for the following 4 years sales were almost at unsustainable levels.  Following becoming an author with PW in 2004 and developing new projects for the Doing It By Design series, sales have risen back to make us busier than ever. I became author of another PW series In 2005 titled Technical For The Terrified. I ceased being an author in 2017 following the change of ownership of PW.

G2DYM Aerials was purchased from Richard Benham-Holman G2DYM on 30 October 2006.   Garex Electronics was purchased from Peter Longhurst G3ZVI on 1 December 2011.