BU2EQ's Resource Page on Ham Radio SSPA building

-
Last Updated on Feb. 10, 2023.

Before We Start......

There is no guarantee of the correctness of the information mentioned in this page, and I WILL NOT take any responsibilities for any kind of your loss following the provided information.

Also, up until now I only have experiences building SSPA for HF to VHF, so if you are looking information for UHF and above, you might not be able to find what you need, although I do plan to go all the way up to 23cm.

One more thing, if you are considering building one so that you can save some money, think twice. Especially if you don't have a lot of knowledge to begin with, like me (I started with knowing nothing more than Ohm's Law), you might end up spending more money than just buying a turn-key one, in addition to the time and labor you need to put on building.

Mechanical Aspect

Before jumping into the RF wonderland, I'd like to mention something mechanical.


Front Panel Designer is a freeware with easy-to-use WYSIWYG interface to design your front/back panels, it can export your design into standard .dxf or .stp format, so you can have your panels made easily:


And it is not just about appearance! You can put screw holes and even "trench" for your LDMOS, export to .stp file and have your cooper spreader/heat sink professionally prepared, so that you don't need to use your elbow grease to tap/mill them.

Sprint Layout costs 50 Euro but it totally worth the money. Unlike KiCAD or other professional PCB design software that start with schematics, SL lets you "just draw the PCB," to me this is a more intuitive way. SL would also be a handy tool if you want to "transcribe"  an existing PCB.

Design Tools

As mentioned before, I started amp building when Ohm's Law was the only knowledge I had, after two years I still don't know much. Not as much as the experts on the RF SSPA Builder Facebook Group do. So I took advantage of some tools that can get me to the right direction.

AE6TY's SimSmith is an Interactive RF Circuit Analysis software, I use it for plotting input/output matching, especially for those who are wondering the length of the coax for your 144MHZ output TLT,  SimSmith will give you an in-the-ball-park solution to begin with.


RF Tools is an online calculator that can generate designs for your filter, coupler, attenuator and more.


Freely Available Designs

YO4HFU's 144MHZ amplifier, you can find PA board, combiner, LPF and controller, there is no geber file to download, but you can transcribe it using  Spring Layout with the PCB information he provides.

DJ0ABR made all his work available for public, including HF PA, 1KW Tuner, PA Controller and SWR bridge. Each of them has BOM, gerber and in-depth building instructions.

If you are really looking for gerber file that you can make PCB and get right into building, EasyEDA might be a good place to look at. What I have found over there include:

S21RC's Arduino Controller with touch screen

More to come......




留言

張貼留言

這個網誌中的熱門文章

典型在夙昔，懷念朱鹿老師

-
前幾天得知，我國中時的理化老師朱鹿老師病逝。 我自己也四十幾歲了，受教於朱老師的時光已經是近三十年前的事情。但回想起來，我能過著、享受著我的「斜槓人生」（大學和碩士主修音樂、在母校英文系上班近15年、這一兩年佔去我最多休閒時間的興趣是無線電，並且嘗試DIY製作許多裝備。）其中很大的部分要歸功國高中時期幾位老師的教導，朱老師就是其中最重要的一位。 「當然兩個都重要！」這是國三面對模擬考（我的學業成績向來都是中等）和學校辦的籃球比賽（我手腳笨拙，籃球比賽這件事情，能為班上做出最大的貢獻應該就是張羅茶水）日期都慢慢接近時，我問朱老師「哪件事情比較重要？」的時候，他的回答。他就是這樣，在課堂中是嚴師（那是個可以體罰學生的時代），課堂外是朋友，要求我們Work hard, play hard，當然我其實是play even harder就是了。 至少就我記憶所及，賞罰分明的朱老師不曾因學生學業成績，對我和同學有任何的差別待遇。這在那個時空背景下，我覺得是非常難得的。國三畢業前夕，大家在報名各種升學考試，因為我和我家大我兩歲的另一位小孩相比，學業成績有相當的差距。父母認為我可能考不上公立高中，幫我填了高職聯招。朱老師得知後，立刻趁著我母親來學校當導護家長時，和她懇談。 「首先，我保證廖威絕對考得上公立高中！雖然去念高職也沒有不好，他在那個體系以後也可能有不錯的發展，但只因為覺得他考不上高中而就叫他去讀高職，這樣是不太好的。他高中絕對考得上的！」以上來自我母親回家後的轉述。 得知朱老師離世的消息時，我正拿著電烙鐵製作無線電功率放大器用的濾波電路，我想老師對我的影響與教化，應該比他理化課時教我的基本電學深遠許多。 老師，一路好走。
閱讀完整內容

The Chinese VHF 500W Kit

-
圖片
People are talking about this super cheap VHF 500W amplifier kits from China,  for $35 it comes with the PCB and all components including the LPF, even on-board couplers for SWR! Pretty good deal, isn't it? Is it? Here's the catch, or maybe I should say: "Here are the catches."? First of all, it is a very "simple" design, trying to squeeze a pair of 600W transistors onto board that was originally designed for 170W FM band . It has no thermal compensation to lower the bias in when the amp gets hot, and speaking of bias, there is only  one potentiometer for the two MRF300s to share, making adjusting IDQ individually impossible. There is no bias switching circuitry either, unlike other popular amp designs that only supply bias when TX, on this amp the bias will be always on, resulting in warmer transistors. Other things to keep in mind: The bias potentiometer, as the schematics suggests,  is placed on the upper side of the voltage divider, which means the bias
閱讀完整內容

便攜可折疊多波段「地調地網」

-
圖片
上次測試了被友台暱稱為「 蚊香地網 」的便攜地網片，效果不錯。 但可惜壓克力板是硬的，無法折疊，攜帶型還是有限。於是想到以 露營用鋁箔睡墊 來當地網素材。為了能在多波段使用，這次的測試會帶入 人工地網 的概念，以一個天調來匹配地網。 進一步查詢發現，市售和友台自製的人工地網，其架構其實就是一個電感調整點和一個電容調整點構成的簡單L Network Matching架構，然後再加上一個RF電流計方便精確調整，以下取自澳洲友台VK2BSY的 網站 ： 由於加上電流表和調整電流表敏感度的裝置（還是那句話：為了精確調整），整個會變成很大盒，不易攜帶野台使用。因此我選用MFJ 16010手動天調來當「地調」，它就是典型一進一出、先電感再電容的L Network Matching匹配機制： 這種簡單的匹配裝置應該可以自製，但我手藝不佳，加上DX Engineer網站上的售價不貴，就和其他要用的東西一起自美國購回。 這次測試的地網系統架構如下： 以香蕉插頭從16010的「transmitter」孔連接一條導線至天調或天線的接地端、「antenna」端則連接一片80公分見方的鋁箔睡墊： 測試現場風勢強大，鋁箔墊得用東西壓好： 以RHM 7350天線、857D及MAT-30自動天調來測試，操作過程如下： 先完全不接地，調整7350的加感線圈，找出底噪最大聲的點。 開啟天線分析儀（沒有天分的話就用機子最小功率發射）並調整「地調」以取得最低之SWR。 開啟自動天調再做最後匹配。 效果還蠻不錯的，15米波段，上述第一步驟完成後，在第二步驟一開始的SWR在2.2上下，透過「地調」調整，取得1.5左右的SWR： 40米波段，天線加感線圈調整完後，SWR大於10，完成接地匹配後，SWR降至1.05： 其他波段的成果也不錯，透過「地調」都能把SWR降到1.5以下，天線阻抗則在45-60間。 今天時間不多，不過也趕緊進行實際通聯測試，除了SSB話務通聯到日本、俄國之外。10瓦FT8訊號也能發射到美東： 目前覺得會被吹走外，這樣的地網還蠻適合輕裝SOTA使用的，過陣子就帶上觀音山試試。
閱讀完整內容