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!

   If, like me, you enjoy flipping through old issues of 73 magazine from the 60s, you're bound to have at least seen the ads for the Transcom SBT-3 three-band SSB tranceiver.  Being made in Escondido CA in the mid-60s, my guess has always been that engineers from other San Diego SSB compnanies such as Don Stoner, Les Earnshaw from Southcom, Herb Johnson, founder of Swan or Faust Gonsett may...  READ MORE
- Robert Nickels (ranickels),  01/16/2021 
  

Model FP-1 "FORESTPHONE"

The Amalgamated Wireless Ltd. (AustralAsia)
Category: Vintage Ham Radio
This short article about the AWA Forestphone was the last one put on the Midwest Classic Radio Net website by for former webmaster George K9GDT before he unfortunately became a Silent Key.  MCRN articleNow that a longer version has been published in Electric Radio magazine I thought I'd include it here as well.Throughout most of the 20th century AWA was Australia's leading electr...  READ MORE
- Robert Nickels (ranickels),  01/13/2021 
   Alexander M. Lewyt died in 1988 at the age of 79, a holder of patents on scores of inventions. His penchant for invention, he once said, was so strong that he had chronic insomnia from lying awake at night envisioning new products. When he learned of undertakers’ difficulty in fastening neckties on corpses, the teen-age Lewyt devised a new kind of bow tie that clipped on. He sold 50,000 of t...  READ MORE
- Robert Nickels (ranickels),  01/08/2021 
  

AN/GRC-9 Bias Battery replacement

Cheap and easy fix using coin cells
Category: Technical
The Korean-war vintage AN/GRC-9 is one of the most useful and fun military field radios for ham use, as with AM and CW modes and 2-12 MHz coverage and a VFO it's all ready to go on several ham bands.    The battery tube superhet receiver is also power-friendly and sensitive and stable enough to copy CW and SSB but has one annoying flaw - the 4 volt bias battery used by the audio...  READ MORE
- Robert Nickels (ranickels),  01/03/2021 
  

Beware of the LED Noisemaker!

MR-16 lamps have no home in the hamshack!
Category: Technical
Halogen type MR-16 lamps are commonly used in track lights and other spot lighting applications so what would be cooler than to drop in LED replacements!   A lot, as it turns out.   The LED replacements are HORRIBLE RFI emitters that totally trashed several ham bands when I unknowingly installed them.Halogen spot lights are 12 volt devices so it's long been common prac...  READ MORE
- Robert Nickels (ranickels),  01/02/2021 
  

Ham radio operators honor legacy of Mars Hill company

Hammarlund was an industry leader for generations
Category: Historic
Here's a link to a nice story in the Madison NC newspaper about area hams paying tribute to the former Hammarlund company that manufactured radios in Mars Hill NC for decades.   There are some neat historiic photos as wellThe paper has a paywall but it looks like you get 5 free articles:HAMMARLUND ARTICLE...  READ MORE
- Robert Nickels (ranickels),  12/12/2020 
  

Ham radio operators honor legacy of Mars Hill company

Hammarlund was an industry leader for generations
Category: Historic
Here's a nice story about how the hams around Mars Hill NC honored the legacy of the Hammarlund company that manufactured radios there for many years.  It's behind a paywall but it looks like you get 5 free articles:LINK to Hammarlund story...  READ MORE
- Robert Nickels (ranickels),  12/12/2020 
   In the days before sat phones, HF SSB was the only practical means of communication once you went beyond line-of-sight distance from civilization.   Forestry crews, scientific exploration teams, mariners, and oil and gas or pipeline workers were among those for home HF SSB was a lifeline.  Portable transceivers like the JRC JSB-20 were used when moving from one location to another a...  READ MORE
- Robert Nickels (ranickels),  12/12/2020 
   Like most people who received a catalog from International Crystal in the 60s, I was always intrigued by their assortment of PC board kits.   There were boards for every stage in a radio transmitter or receiver and they could be combined to make almost anything - from converters to complete radios.   But little did I know that International actually did just that when they went...  READ MORE
- Robert Nickels (ranickels),  12/01/2020 
    Not much more to be said - if you can't find it here you probably don't need to know!RADIO BOOKSMany are from non-US sources, some are in languages other than English.   Included are 23 volumes of Riders manuals, Beitmans most needed diagrams up til 1967, and much more.   Incredible resource!...  READ MORE
- Robert Nickels (ranickels),  11/02/2020 

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