{"title":"Science","description":"\u003cp\u003eProducts aimed at radio enthusiasts\u003c\/p\u003e","products":[{"product_id":"bottle-opener","title":"Radio Callsign Bottle Opener","description":"\u003cp\u003e A fantastic gift for a radio operator, a chunky wood and stainless steel bottle opener displaying a radio callsign on one side and 'Cheers!' on the reverse.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e14cm long x 4cm wide(at widest point) x 1.8cm deep (handle).\u003c\/li\u003e\n\u003cli\u003eStainless steel bottle opener with chunky wooden handle.\u003c\/li\u003e\n\u003cli\u003eNot dishwasher safe.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eEngravable space on handle is 1.5cm high x 7cm long.\u003c\/p\u003e\n\u003cp\u003eCustomised and personalised items are non-returnable unless the goods are faulty, please see terms of sale for further details.\u003c\/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":57160123580761,"sku":"BOPEN1","price":7.5,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3293_70ad97af-6050-42e7-9d48-72fa0f556535.jpg?v=1782817528"},{"product_id":"stargazer-cotton-tote-bag","title":"Stargazer Cotton Tote Bag","description":"\u003cp dir=\"ltr\"\u003e\u003cspan\u003eCarry a little wonder wherever you go. This cotton tote bag features the word “stargazer” paired with subtle star details, blending minimalist style with a love for the night sky. Designed for everyday use, it’s perfect for errands, books, groceries, or daily essentials.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp dir=\"ltr\"\u003e\u003cspan\u003eWhether you’re an astronomer, a skywatcher, or someone who simply enjoys looking up, this tote celebrates curiosity and imagination. Durable, reusable, and effortlessly versatile, it makes a thoughtful gift for space lovers and science enthusiasts.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp dir=\"ltr\"\u003e\u003cspan\u003eMaterial: 100% 5oz Cotton\u003c\/span\u003e\u003c\/p\u003e\n\u003cp dir=\"ltr\"\u003e\u003cspan\u003eColour: Black - \u003c\/span\u003e\u003cspan\u003eSingle side printed.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp dir=\"ltr\"\u003e\u003cspan\u003eDimensions: 38cm wide x 43cm high\u003c\/span\u003e\u003c\/p\u003e\n\u003cp dir=\"ltr\"\u003e\u003cspan\u003eHandle Drop: 30cm\u003c\/span\u003e\u003c\/p\u003e\n\u003cp dir=\"ltr\"\u003e\u003cspan\u003eCare Instructions: Gentle hand wash only, do not iron the transfer, do not tumble dry. Machine washing is not recommended as it may cause shrinkage with natural cotton.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp dir=\"ltr\"\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":57432373494105,"sku":"SGTB3843BK","price":9.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/StargazerBagoutdoorswithscope.png?v=1772701611"},{"product_id":"slate-coaster","title":"Quarter-Wave Antenna Formula Slate Coaster","description":"\u003cp\u003eA stylish and practical gift for radio enthusiasts, this natural slate coaster is laser engraved with the classic \u003cstrong\u003equarter-wave antenna formula\u003c\/strong\u003e: \u003cstrong\u003eL(m) = 75 × VF ÷ f(MHz)\u003c\/strong\u003e. This formula is used to calculate the approximate length of a quarter-wave vertical antenna or radial, where \u003cstrong\u003eL\u003c\/strong\u003e is the antenna length in metres, \u003cstrong\u003eVF\u003c\/strong\u003e is the velocity factor of the material, and \u003cstrong\u003ef\u003c\/strong\u003e is the operating frequency in megahertz.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, antenna length is one of the most important factors in getting strong, efficient reception and transmission. A quarter-wave vertical is a popular antenna design because it is simple, compact, and effective across many bands. Whether used as a shack coaster, workshop reference, or conversation piece, this engraved slate design combines radio heritage with genuinely useful technical information. Its dark natural stone and crisp engraving make it ideal for any radio room, desk, or operating position.\u003c\/p\u003e\n\u003cp\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":57561923289433,"sku":"4SLT10CR-QWA","price":4.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3285.jpg?v=1782137888"},{"product_id":"half-wave-dipole-formula-slate-coaster","title":"Half-Wave Dipole Formula Slate Coaster","description":"\u003cp\u003eA beautifully detailed slate coaster for radio enthusiasts, laser engraved with the classic \u003cstrong\u003ehalf-wave dipole formula\u003c\/strong\u003e: \u003cstrong\u003eL(m) = 150 × VF ÷ f(MHz)\u003c\/strong\u003e. This formula is used to calculate the total length of a half-wave dipole antenna, where \u003cstrong\u003eL\u003c\/strong\u003e is the overall end-to-end antenna length in metres, \u003cstrong\u003eVF\u003c\/strong\u003e is the velocity factor of the wire or material being used, and \u003cstrong\u003ef\u003c\/strong\u003e is the operating frequency in megahertz.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, the half-wave dipole is one of the most trusted and widely used antenna designs. It is simple, effective, and a great starting point for building antennas for HF bands such as 40m, 20m, 15m, and 10m. The engraved diagram shows the dipole split into two equal halves, making it a useful visual reminder that each side of the antenna is approximately \u003cstrong\u003eL\/2\u003c\/strong\u003e from the centre feed point. Practical, decorative, and full of radio heritage, this coaster is ideal for the shack, workshop, desk, or as a thoughtful gift for anyone who enjoys amateur radio or short wave listening.\u003c\/p\u003e\n\u003cp\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58373130649945,"sku":"4SLT10CR-HWA","price":4.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3287.jpg?v=1782138187"},{"product_id":"morse-code-reference-slate-coaster","title":"Morse Code Reference Slate Coaster","description":"\u003cp\u003eA classic piece for any radio shack, this natural slate coaster is laser engraved with a clear \u003cstrong\u003eMorse code reference chart\u003c\/strong\u003e, showing the dots and dashes for the full alphabet and numbers 0–9. The design is both decorative and practical, giving ham radio operators and short wave listeners a quick visual reminder of the International Morse characters used for CW communication.\u003c\/p\u003e\n\u003cp\u003eMorse code remains an important and much-loved part of amateur radio. It is efficient, reliable, and can often get through when voice signals are weak or noisy. Whether used by an experienced CW operator, someone learning Morse for the first time, or a short wave listener decoding signals on the bands, this coaster makes a useful desk-side reference as well as a smart radio-themed gift. Laser engraved into natural slate, each piece has a distinctive rugged edge and a traditional technical look that suits any shack, workshop, or operating desk.\u003c\/p\u003e\n\u003cp\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58373144707417,"sku":"4SLT10CR-MCR","price":4.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3290.jpg?v=1782138351"},{"product_id":"ohm-s-law-power-formulas-slate-coaster","title":"Ohm’s Law Power Formulas Slate Coaster","description":"\u003cp\u003eA practical and eye-catching slate coaster for radio enthusiasts, laser engraved with essential \u003cstrong\u003eOhm’s Law and power formulas\u003c\/strong\u003e: \u003cstrong\u003eV = I × R\u003c\/strong\u003e, \u003cstrong\u003eP = V × I\u003c\/strong\u003e, \u003cstrong\u003eP = V² ÷ R\u003c\/strong\u003e, and \u003cstrong\u003eP = I² × R\u003c\/strong\u003e. These formulas describe the relationship between voltage, current, resistance, and power — the core electrical principles behind transmitters, receivers, antennas, power supplies, dummy loads, and test equipment.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, these calculations are genuinely useful at the bench or in the shack. They help when checking current draw, estimating power dissipation, choosing suitable resistors, understanding dummy loads, or working out whether equipment and cables are being operated safely. Laser engraved into natural slate, this coaster combines a rugged technical look with a handy reference that feels right at home beside a transceiver, soldering station, or workshop mug.\u003c\/p\u003e\n\u003cp\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58373153718617,"sku":"4SLT10CR-OHM","price":4.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3291.jpg?v=1782138568"},{"product_id":"morse-code-popular-abbreviations-slate-coaster","title":"Morse Code Popular Abbreviations Slate Coaster","description":"\u003cp\u003eA distinctive slate coaster for Morse code and amateur radio enthusiasts, laser engraved with a handy selection of popular \u003cstrong\u003eCW and Morse operating abbreviations\u003c\/strong\u003e. The design includes familiar shorthand such as \u003cstrong\u003eAR\u003c\/strong\u003e for end of message, \u003cstrong\u003eAS\u003c\/strong\u003e for wait, \u003cstrong\u003eBK\u003c\/strong\u003e for break, \u003cstrong\u003eR\u003c\/strong\u003e for roger\/received, \u003cstrong\u003eRPT\u003c\/strong\u003e for repeat, \u003cstrong\u003eTU\u003c\/strong\u003e for thank you, \u003cstrong\u003e73\u003c\/strong\u003e for best regards, and other common terms used during Morse contacts.\u003c\/p\u003e\n\u003cp\u003eThese abbreviations are part of the language and rhythm of CW operating, helping radio operators keep messages short, efficient, and easy to copy even when signals are weak or noisy. For ham radio operators, Morse learners, and short wave listeners, this coaster is both a useful desk-side reference and a celebration of traditional radio communication. Laser engraved into natural slate, it has a rugged, timeless look that suits any radio shack, operating desk, or workshop.\u003c\/p\u003e\n\u003cp\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58373161353561,"sku":"4SLT10CR-MCA","price":4.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3288.jpg?v=1782138765"},{"product_id":"ohm-s-law-power-formulas-slate-coaster-copy","title":"Decibels Power Ratio Slate Coaster","description":"\u003cp\u003eA smart and technical slate coaster for radio enthusiasts, laser engraved with the essential \u003cstrong\u003edecibel power ratio formula\u003c\/strong\u003e: \u003cstrong\u003edB = 10 log₁₀(P₂ ÷ P₁)\u003c\/strong\u003e. This formula is used to compare two power levels, where \u003cstrong\u003eP₁\u003c\/strong\u003e is the input power and \u003cstrong\u003eP₂\u003c\/strong\u003e is the output power. In amateur radio, decibels are used everywhere — from antenna gain and feeder loss to amplifier performance, filters, attenuators, and signal strength comparisons.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, understanding dB makes it much easier to judge what a change in equipment or antenna system really means. A small number of decibels can represent a meaningful change in power or received signal, while larger values quickly show major gain or loss. The engraved gain diagram and S-meter style graphic make this coaster both a useful reference and a great shack accessory. Laser engraved into natural slate, it has a rugged radio-room look that is ideal for an operating desk, workshop, or gift for anyone interested in RF, antennas, and signal performance.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 0.875rem;\"\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/span\u003e\u003cbr\u003e\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58373166235993,"sku":"4SLT10CR-DBL","price":4.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3286.jpg?v=1782138908"},{"product_id":"set-of-two-morse-code-slate-coasters","title":"Set of Two Morse Code Slate Coasters","description":"\u003cp\u003eBuy both Morse Code Slate Coasters as a set for a special price!\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"text-decoration: underline;\"\u003eMorse Code Popular Abbreviations Slate Coaster\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eA distinctive slate coaster for Morse code and amateur radio enthusiasts, laser engraved with a handy selection of popular \u003cstrong\u003eCW and Morse operating abbreviations\u003c\/strong\u003e. The design includes familiar shorthand such as \u003cstrong\u003eAR\u003c\/strong\u003e for end of message, \u003cstrong\u003eAS\u003c\/strong\u003e for wait, \u003cstrong\u003eBK\u003c\/strong\u003e for break, \u003cstrong\u003eR\u003c\/strong\u003e for roger\/received, \u003cstrong\u003eRPT\u003c\/strong\u003e for repeat, \u003cstrong\u003eTU\u003c\/strong\u003e for thank you, \u003cstrong\u003e73\u003c\/strong\u003e for best regards, and other common terms used during Morse contacts.\u003c\/p\u003e\n\u003cp\u003eThese abbreviations are part of the language and rhythm of CW operating, helping radio operators keep messages short, efficient, and easy to copy even when signals are weak or noisy. For ham radio operators, Morse learners, and short wave listeners, this coaster is both a useful desk-side reference and a celebration of traditional radio communication. Laser engraved into natural slate, it has a rugged, timeless look that suits any radio shack, operating desk, or workshop.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"text-decoration: underline;\"\u003eMorse Code Reference Slate Coaster\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eA classic piece for any radio shack, this natural slate coaster is laser engraved with a clear \u003cstrong\u003eMorse code reference chart\u003c\/strong\u003e, showing the dots and dashes for the full alphabet and numbers 0–9. The design is both decorative and practical, giving ham radio operators and short wave listeners a quick visual reminder of the International Morse characters used for CW communication.\u003c\/p\u003e\n\u003cp\u003eMorse code remains an important and much-loved part of amateur radio. It is efficient, reliable, and can often get through when voice signals are weak or noisy. Whether used by an experienced CW operator, someone learning Morse for the first time, or a short wave listener decoding signals on the bands, this coaster makes a useful desk-side reference as well as a smart radio-themed gift. Laser engraved into natural slate, each piece has a distinctive rugged edge and a traditional technical look that suits any shack, workshop, or operating desk.\u003c\/p\u003e\n\u003cp\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58382598406489,"sku":"4SLT10CR-MCA","price":7.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/Set_of_2_morse_coasters.png?v=1782816913"},{"product_id":"radio-callsign-aluminium-keyring-bottle-and-can-opener","title":"Radio Callsign Aluminium Keyring Bottle and Can Opener","description":"\u003cp\u003e A fantastic gift for a radio operator, a light weight key ring aluminium bottle and can opener displaying a radio callsign.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e8cm long x 1.2cm wide x 1.2cm deep\u003c\/li\u003e\n\u003cli\u003eAnodised aluminium laser engraved bottle and can opener\u003c\/li\u003e\n\u003cli\u003eNot dishwasher safe.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eAvailable in five fantastic colours and seven lettering styles.\u003c\/p\u003e\n\u003cp\u003eCustomised and personalised items are non-returnable unless the goods are faulty, please see terms of sale for further details.\u003c\/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58399086018905,"sku":"BOPEN-ALUM-CSGN","price":4.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/IMG_3343.jpg?v=1782817065"},{"product_id":"set-of-four-radio-formulae-slate-coasters","title":"Set of Four Radio Formulae Slate Coasters","description":"\u003cp\u003eBuy all four Radio Formulae Slate Coasters as a set for a special price!\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"text-decoration: underline;\"\u003eOhm’s Law Power Formulas Slate Coaster\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eA practical and eye-catching slate coaster for radio enthusiasts, laser engraved with essential \u003cstrong\u003eOhm’s Law and power formulas\u003c\/strong\u003e: \u003cstrong\u003eV = I × R\u003c\/strong\u003e, \u003cstrong\u003eP = V × I\u003c\/strong\u003e, \u003cstrong\u003eP = V² ÷ R\u003c\/strong\u003e, and \u003cstrong\u003eP = I² × R\u003c\/strong\u003e. These formulas describe the relationship between voltage, current, resistance, and power — the core electrical principles behind transmitters, receivers, antennas, power supplies, dummy loads, and test equipment.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, these calculations are genuinely useful at the bench or in the shack. They help when checking current draw, estimating power dissipation, choosing suitable resistors, understanding dummy loads, or working out whether equipment and cables are being operated safely. Laser engraved into natural slate, this coaster combines a rugged technical look with a handy reference that feels right at home beside a transceiver, soldering station, or workshop mug.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDecibels Power Ratio Slate Coaster\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eA smart and technical slate coaster for radio enthusiasts, laser engraved with the essential \u003cstrong\u003edecibel power ratio formula\u003c\/strong\u003e: \u003cstrong\u003edB = 10 log₁₀(P₂ ÷ P₁)\u003c\/strong\u003e. This formula is used to compare two power levels, where \u003cstrong\u003eP₁\u003c\/strong\u003e is the input power and \u003cstrong\u003eP₂\u003c\/strong\u003e is the output power. In amateur radio, decibels are used everywhere — from antenna gain and feeder loss to amplifier performance, filters, attenuators, and signal strength comparisons.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, understanding dB makes it much easier to judge what a change in equipment or antenna system really means. A small number of decibels can represent a meaningful change in power or received signal, while larger values quickly show major gain or loss. The engraved gain diagram and S-meter style graphic make this coaster both a useful reference and a great shack accessory. Laser engraved into natural slate, it has a rugged radio-room look that is ideal for an operating desk, workshop, or gift for anyone interested in RF, antennas, and signal performance.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"text-decoration: underline;\"\u003eHalf-Wave Dipole Formula Slate Coaster\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eA beautifully detailed slate coaster for radio enthusiasts, laser engraved with the classic \u003cstrong\u003ehalf-wave dipole formula\u003c\/strong\u003e: \u003cstrong\u003eL(m) = 150 × VF ÷ f(MHz)\u003c\/strong\u003e. This formula is used to calculate the total length of a half-wave dipole antenna, where \u003cstrong\u003eL\u003c\/strong\u003e is the overall end-to-end antenna length in metres, \u003cstrong\u003eVF\u003c\/strong\u003e is the velocity factor of the wire or material being used, and \u003cstrong\u003ef\u003c\/strong\u003e is the operating frequency in megahertz.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, the half-wave dipole is one of the most trusted and widely used antenna designs. It is simple, effective, and a great starting point for building antennas for HF bands such as 40m, 20m, 15m, and 10m. The engraved diagram shows the dipole split into two equal halves, making it a useful visual reminder that each side of the antenna is approximately \u003cstrong\u003eL\/2\u003c\/strong\u003e from the centre feed point. Practical, decorative, and full of radio heritage, this coaster is ideal for the shack, workshop, desk, or as a thoughtful gift for anyone who enjoys amateur radio or short wave listening.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"text-decoration: underline;\"\u003eQuarter-Wave Antenna Formula Slate Coaster\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eA stylish and practical gift for radio enthusiasts, this natural slate coaster is laser engraved with the classic \u003cstrong\u003equarter-wave antenna formula\u003c\/strong\u003e: \u003cstrong\u003eL(m) = 75 × VF ÷ f(MHz)\u003c\/strong\u003e. This formula is used to calculate the approximate length of a quarter-wave vertical antenna or radial, where \u003cstrong\u003eL\u003c\/strong\u003e is the antenna length in metres, \u003cstrong\u003eVF\u003c\/strong\u003e is the velocity factor of the material, and \u003cstrong\u003ef\u003c\/strong\u003e is the operating frequency in megahertz.\u003c\/p\u003e\n\u003cp\u003eFor ham radio operators and short wave listeners, antenna length is one of the most important factors in getting strong, efficient reception and transmission. A quarter-wave vertical is a popular antenna design because it is simple, compact, and effective across many bands. Whether used as a shack coaster, workshop reference, or conversation piece, this engraved slate design combines radio heritage with genuinely useful technical information. Its dark natural stone and crisp engraving make it ideal for any radio room, desk, or operating position.\u003c\/p\u003e\n\u003cp\u003eThese coasters are supplied with four soft adhesive feet so they do not mark surfaces. Putting four or six together would make an ideal gift.\u003c\/p\u003e\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision laser engraved design\u003c\/li\u003e\n\u003cli\u003eCrafted from natural grey slate\u003c\/li\u003e\n\u003cli\u003e10cm diameter and 4mm thick slate coaster with a rustic bevelled edge\u003c\/li\u003e\n\u003cli\u003eSoft sponge feet included\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease note slate coasters are not dishwasher safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eDesign Copyright Notice\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAll designs are the intellectual property of Primary 9 Designs and are protected by copyright.\u003c\/p\u003e\n\u003cp\u003eThese products are supplied for\u003cstrong\u003e \u003c\/strong\u003epersonal use only. The designs may not be reproduced, copied, distributed, modified, or used to create products for resale without prior written permission from Primary 9 Designs.\u003c\/p\u003e\n\u003cp\u003ePurchase of this item does not transfer copyright or grant a commercial licence to reproduce or sell the design in any form.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan style=\"text-decoration: underline;\"\u003eLarge Orders\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eLooking to order larger quantities? We are happy to provide bespoke lead time and shipping quotations for bulk orders, schools, clubs, care homes, events and organisations. Please contact us and we'll help find the most cost-effective shipping option for your order.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Primary 9 Designs","offers":[{"title":"Default Title","offer_id":58433121255769,"sku":"4SLT10CR-4RAD","price":14.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/9230\/3961\/files\/Set_of_4_radio_coasters_2x2_layout.png?v=1782816477"}],"url":"https:\/\/primary9designs.com\/collections\/radio.oembed","provider":"Primary 9 Designs","version":"1.0","type":"link"}