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Author Topic: Adding a huff and puff circuit to an Invader 2000 transmitter  (Read 519 times)

N4MQ

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Adding a huff and puff circuit to an Invader 2000 transmitter
« on: January 06, 2022, 05:18:23 PM »

After going thru the entire invader 2000 and getting it working ( crystal filters on them all seem to fail, I have swept 6 of them ) I decided to turn to the drifting issue.  It seems to drift almost like my novice T-150 transmitter.  A huff snd puff circuit is one way to lock the vfo signal after you set it.

Adding a digital Huff and Puff circuit uses a varicap diode to lock the vfo and prevent if from drifting.  The circuit uses a 40 MHZ crystal and some digital counters/ D flip flop to feed a correction voltage biasing the varicap diode.  Really is nifty to have a boat anchor that is solid frequency wise.  Photos show my board and the shield/mounting bracket.  Enjoy Woody

I can not clip in photos???  how is that done? help

link:
https://www.qsl.net/py4bl/vfoesta.htm

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WA2CWA

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  • Posts: 710
    • ManualMan
Re: Adding a huff and puff circuit to an Invader 2000 transmitter
« Reply #1 on: January 06, 2022, 10:11:48 PM »

After going thru the entire invader 2000 and getting it working ( crystal filters on them all seem to fail, I have swept 6 of them ) I decided to turn to the drifting issue.  It seems to drift almost like my novice T-150 transmitter.  A huff snd puff circuit is one way to lock the vfo signal after you set it.

Adding a digital Huff and Puff circuit uses a varicap diode to lock the vfo and prevent if from drifting.  The circuit uses a 40 MHZ crystal and some digital counters/ D flip flop to feed a correction voltage biasing the varicap diode.  Really is nifty to have a boat anchor that is solid frequency wise.  Photos show my board and the shield/mounting bracket.  Enjoy Woody

I can not clip in photos???  how is that done? help

link:
https://www.qsl.net/py4bl/vfoesta.htm
the manual way, type [image] copy the link location of the picture[/image]
NOTE: when actually doing this, replace image with IMG





Pete, wa2cwa
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N4MQ

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  • Posts: 577
Re: Adding a huff and puff circuit to an Invader 2000 transmitter
« Reply #2 on: January 07, 2022, 02:25:14 AM »

If the images are on my pc, how does that work, I have tried that unsuccessfully, Woody
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WA5VGO

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  • Posts: 120
Re: Adding a huff and puff circuit to an Invader 2000 transmitter
« Reply #3 on: January 07, 2022, 07:09:38 AM »

If the drift is as almost as bad as a T-150, a huff and puff probably won’t work. While they can make a good VFO a great VFO, but the can’t make a lousy one a good one.

Darrell
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WA2CWA

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  • Posts: 710
    • ManualMan
Re: Adding a huff and puff circuit to an Invader 2000 transmitter
« Reply #4 on: January 07, 2022, 11:01:15 AM »

If the images are on my pc, how does that work, I have tried that unsuccessfully, Woody

As far as I can tell, eham does not provide the ability to upload pictures from your computer into a post. There are sites where you can store your pictures  and then use the info I provided to point to them.

Here's a picture from your web site using my method:



Pete, wa2cwa

« Last Edit: January 07, 2022, 11:08:57 AM by WA2CWA »
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N4MQ

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Re: Adding a huff and puff circuit to an Invader 2000 transmitter
« Reply #5 on: January 07, 2022, 05:39:10 PM »

Today as I was getting the unit back together, I took a couple of short videos showing the operation of the huff and puff ckt.  Posting photos has been challanging, so this is a chance to show the operation, Woody

https://www.youtube.com/watch?v=rDf9zdfHEeU

https://www.youtube.com/watch?v=SbKNF3UHMTg



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N4MQ

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  • Posts: 577
Re: Adding a huff and puff circuit to an Invader 2000 transmitter
« Reply #6 on: February 11, 2022, 04:34:11 AM »

As an update, the huff n puff is working very well, allows me to stay on frequency for ssb conversations without constant dial twiddling.  Yesterday I found that by adding two push buttons which feed ground or 10 volts thru a 100 megohm resistor to the summing node, I can tune the vfo up or down about 2 kc from the center frequency.  This slow adjustment provided the careful tuning needed to get on frequency with the net, rather than jumping above or below the frequency with the vfo knob.

I will be adding one of these circuits to my HQ-170 to calm its ass down, cause it also drifts greatly even with a muffin fan, that runs quietly.  I slow fans down by adding a couple of microfarads in series with the power line to provide a reactive voltage drop slowing the fan but still allowing good motor starting characteristics. Enjoy, woody
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N4MQ

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  • Posts: 577
Re: Adding a huff and puff circuit to an Invader 2000 transmitter
« Reply #7 on: February 11, 2022, 06:08:29 AM »

Here is a short video showing the operation of the huff n puff and my slow tuning control box.  The Johnson Invader is now stable and adjustable to any desired frequency within 10 or fewer cycles.  A really good addition to this old boat anchor.  Enjoy 73 :D ;)

https://www.youtube.com/watch?v=JgyFeSFxckw
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