RAN Technology

All Band Inexpensive 40 Watt Transmitter

Vintage Ham Radio 0 Comments 07/09/2020 

a great "first homebrew xmtr" project

Posted By: Robert Nickels (ranickels)


Jay Miller KK5IM recently wrote an article in Electric Radio magazine about fulfilling his dream of building a homebrew "AM Kilowatt" transmitter (375 watts output by today's standards).     His crystal-controlled exciter that drive the 813 was based on his Novice transmitter, which was built by his grand-uncle back in the 1960s when Novice class hams were lmited to less than 75 watts and crystal control.    The design came from an 1961 ARRL Handbook article (attached below) called "All Band Inexpensive 40 watt Transmitter", that used the classic line-up of a 6AG7 oscillator followed by an 807 or 1625 PA.    (The 1625 is identical to the 807 but has a 12 volt filament, which would require a different filament connection, but was commonly available for pennies from military surplus dealers at the time).  

This circuit would be an ideal "first homebrew rig" starting point because the parts are still inexpensive and not difficult to find (variable capacitors being the possible exception),  it can be adapted to any ham band by choosing the right L-C values without the complexity of bandswitching, and it has everything needed to actually use on the air, including metering and provision for spotting the crystal requency with the receiver.   (Back in the day of crystal control it was common to work "split" where each station tuned to the crystal frequency of the other).

The coils described are made from cutting sections of  "Air Dux" to the required length.   Air Dux and similar coils were commonly available at the time and not expensive but today that's no longer the case.   For the HF range, PVC pipe is a suitable coil form, or there are articles describing how to make the exact same type of self-supported air dielectric coils using a bit of plastic and glue.   A very good article by W3JIP showing how this is done appeared in QST magazine and is also linked below.  Thanks to the ARRL for making this needed information available!

Hamfests and online sources will provide all the parts needed with a little patience.  Hammond is the best source for new power transformers and chokes and while not inexpensive, making a separate power supply as shown makes it easy to use with future projects.

One thing that isn't included is a T/R switch or relay to switch the antenna between transmitter and receiver and to mute the receiver during TX.   I can solve that problem however!   This is a perfect application for my VERSA-TR which was described in the December 2018 issue of QST and is available in kit from from Hayseed Hamfest.  In addition to automatically sensing and switching the antenna, it can mute the receive audio and by connecting amplified type speaker(s) a pleasant sidetone is generated for CW monitoring.

Hams have been using vacuum tubes longer than anyone but it's the guitar players who have kept tube manufacturers in business and amplifier builders that have provided companies with sufficient volume to keep making transformers and other components.   So all hams wishing to re-live the golden age of building their own ham gear that is still very usable on the air need to do is take advantage of these sources and dust off a classic transmitter design like this one.



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Description Comment  
W3JIP article on making air-core homebrew inductor It's easy! Courtesy ARRL. Visit www.arrl.org to learn all about ham radio!
1961 All Band Homebrew 40 watt transmitter courtesy ARRL handbook 1961. Visit www.arrl.org to learn all about ham radio!


Ed Marriner, W6BLZ/W6XM (SK)

One of ham radio's most prolific builders and authors
Category: Historic
 This tribute to Ed Marriner will be updated over time.   Having known his writings since my earlies ham days in the 1960s, I knew about the "SSB Transceiver from a BC453" conversion article/booklet, but until I had the good fortune to acquire two homebrew SSB transceivers made by his good friend Ernie Mason W6IQY did I know that my vintage SSB friend Lynn Fisk K5LYN was a...  READ MORE
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- Robert Nickels (ranickels),  09/12/2020 

why 50 ohms?

The Forgotten Impedance
Category: Technical
 Why do we use 50 ohm cables?    If you're like most hams the answer is:  "I dunno!"In fact, it's a compromise (like most things in life) - between lowest loss when handling power and voltage breakdown, as Belden engineer Steve Lampen explains hereA pdf copy can be found below as well.   And now you know!...  READ MORE
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"Crystal Plugs"

DIY version by "RAN Crystals"
Category: Crystal Replacement
Crystal sockets were popular for pluging in ... crystals, of all things!   But they were also used for other purposes, such as the antenna relay connection on some EF Johnson transmitters.    If you want to connect a VFO to a transmitter with just a crystal socket, for example, you're going to have to either carve up an old FT-243 type crystal or if you want to outboar...  READ MORE
- Robert Nickels (ranickels),  09/01/2020 

A visit to the D J Everett III Radio Room

Honoring the legacy of a small town radio station owner
Category: Historic
Many successful career people are grateful for mentoring they received on the way to the top. But few have honored a memory as passionately as has been done by Beth Mann.   She's the owner of Ham Broadcasting which owns five stations in western Kentucky but the story is about her mentor, the late DJ Everett III who started WKDZ in Cadiz Kentucky in 1966.   Everett worked as...  READ MORE
- Robert Nickels (ranickels),  08/14/2020 
   Bob Heil's favorite radio is the Moseley CM-1 which the developer, John Clemmons, told Carl Moseley stood for Clemens Manufacturing number 1.   "No", Mr. Moseley said, "That stands for Carl Moseley number 1!"As that may be, there's yet another CM-1 receiver and it was made by the Multi Products Company of Oak Park, Michigan.As wikipedia states:  "CON...  READ MORE
- Robert Nickels (ranickels),  08/13/2020 

Bias control of Class E amplfiers

Previously undocumented phenomenon
Category: Technical
Micro SDR innovator Guido PE1NNZ has implemented polar modulation using an Arduino MCU and a class E PA.   For more informartion on this fascinating project, join the discussion group at https://groups.io/g/ucxInitially, Guido's design implemented the polar or EER modulation scheme using modifications to the QCX CW transceiver hardware in the traditional way as described by Leonard K...  READ MORE
- Robert Nickels (ranickels),  06/20/2020 
    I'm always intrigued by the odd and unusual ham gear that I remember seeing in catalogs as a kid but have seldom seen after hundreds of hamfests and uncountable for sale listings.   One such is the Lysco mobile transmitter which was produced by the Lysco Manufacturing Company of 1401 Clinton St. Hoboken NJ between 1949 and 1953.   Despite being a very cute and co...  READ MORE
- Robert Nickels (ranickels),  06/06/2020 

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