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The image above is the "Soup'er Up'er" add-on circuit board for the Four State QRP Group's Bayou Jumper radio kit.
This board adds the following features to your Bayou Jumper:
- Sidetone [in the Headphones] during transmit Key-Down
- Receive muting during transmit
- Fine Tuning for the Receive
- NMØS's Hi-Per-Mite CW Filter adapted to the Bayou Jumper
The Soup'er Up'er is being sold as a kit by Four State QRP Group
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The photo above is my Four State QRP Group Bayou Jumper, with the added Filter In/Out Toggle Switch & the Fine Tuning knob.
This is a fun radio (kit) to build and to use.
Using it, you rather feel you are participating as a Spy Radio Operator from early on during WWII.
You may even get the fever to read some of the many books available about the radios and the brave people that used them.
There is a Bayou Jumper Yahoo Group you can join for discussions and photos of many of the kits people have built, and how they 'hacked' or 'tricked-out' their Bayou Jumper.
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Sidetone for the Bayou Jumper:
As designed, when you are transmitting, there is nothing to be heard in the headphones. If like me, you need or want to hear what you are doing while sending CW, you needed an extra receiver to monitor your transmissions. Now that is just fine if you are home in your shack and have a spare receiver. But if you want to use your Bayou Jumper for SOTA (Summits On The Air), or in the park... well you get the idea, carrying along an additional HF Receiver might just be unacceptable.
So, to get my Bayou Jumper ready for Field Day, I decided to add a sidetone to my radio.
Why Mute the Receiver Audio:
Normally, the Bayou Jumper removes power from the audio section during transmit. To add the Sidetone feature, the audio section needed to be powered up.
With the audio section powered up during transmit, a loud click was heard in the headphones because of the transmit signal being fed into the audio from the receiver. Powering down the Receiver was thought not an option since leaving it powered aided it's stability.
Given that, muting the audio coming from the Receiver during transmit mode seemed the best option.
A CW Audio Filter (the Hi-Per-Mite):
The Bayou Jumper, as you know, has a Regen Receiver. It works very good, may I say it is impressive, in fact, I have tuned the band and heard a few signals thinking the band was down on that day, before realizing I had NOT hooked up the Antenna !! Really, I am not exagerating.
However, given that the Regen Receiver is not very 'selective', I thought I would like to use a filter between the Headphone Jack and my Headphones. There are a number of good ones available from numerous QRP Groups, but the Four State QRP Group 'Hi-Per-Mite' has had very good reviews and I already had one built in a box I could just plug-in and try out.
To my delight, the Hi-Per-Mite was the Cat's Meow for filtering the audio and really giving me some 'selectivity'. And I need it because I really struggle trying to copy CW... on any radio.
Here we go again, something else that would have to be carried along with the radio on Field Day, so let's add it to the board with the Sidetone and Receive Audio Mute.
I contacted David Cripe - NMØS to get permission to use his Hi-Per-Mite circuit on this board, and being the supportive person he is, he gave me permission.
Fine Tuning:
The Hi-Per-Mite does a bang-up job filtering the audio signals, but now I noticed how 'twitchy' the Main Tuning knob was. It was noticable before, both with the CW audio filter in use, it really took a lot of finesse to get the desired signal just right. Okay, looks like a Fine Tuning circuit is needed here.
There are some simple ways to accomplish this, and would be great to use in the Bayou Jumper, if added during the original building process. But my Bayou Jumper was built and the receiver all tuned up and the Toroid 'glued down' so to speak. I wanted a ciruit I could put in series with the Bayou Jumper Tuning Voltage, and apply a small positive or negative offset to the Tuning Voltage when I turn a pot up or down from the center position.
In theory (don't forget component tolerances part in this game), the circuit I used will leave the Bayou Jumper Tuning Voltage unchanged with the Fine Tuning pot in it's center position. And I feel this would be most desirable for my radio, and all those many 100's of Bayou Jumpers already built.
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