[SignalOne] The CX7A Lives!

[K5OG]

Good work getting it going.
Several years ago we did some audio boards using LM380s.  They were 
based on an earlier design from S1 News and work great.
I still have a few of the PC boards (unpopulated) if you're interested.
As for the TX power and low drive, check Q 3 and 4 on the RF driver board.
And have you tried switching to manual tune and is it any better? 
Contacts on the wafer switches in the tube cage may be blown out. I've 
seen it many times over the years.
Just a few suggestions and good luck with your troubleshooting.
Fred
K5OG
www.signalone.com

On 11/6/2024 7:04 PM, jerry wrote:
>
>
> This list is for discussions regarding collecting, repair, use and 
> sale of Signal/One radios and accessories.
>
> Documentation on Signal/One radios can be found at 
> http://www.hamanuals.com and several other sites on the Web.
>
> .
> Just a little.  I have upgraded the power supply to three-terminal 
> regulators.  It had a fault with the T/R switching that was driving me 
> nuts ... all due to the 5V regulator.  I had neglected to bypass it, 
> and it was oscillating.  An SMD .1uF across the input fixed it right up.
>
> Now it receives.  Both PTOs work.  The crystal calibrator works. How 
> old fashioned!  A digital-readout rig with a crystal calibrator!  I 
> haven't installed an audio amplifier yet.  The original one had 
> shorted and let out its smoke.  I hooked up the low level audio to the 
> "patch" connector on the back panel.  And plugged in a Soviet-surplus 
> high-impedance headset left over from a crystal radio project.  The S 
> meter works.
>
> It also transmits.  A little.  I am getting 50W out in "tune" on 40M.  
> Nothing on any other band.  There is no displayed screen current.  And 
> no displayed "drive", either.  It also transmits CW with my Vibroplex 
> bug plugged into the EXT KEY jack.  The keyer works, but I need a 
> 3/16" plug for it.  And I just got the radio to transmit SSB!
>
> If the tube is tired, I have another one.  But I don't think that's 
> the problem.  Pretty sure that the "drive" metering is before the tube.
>
> Given that there's output on 40 but no other band, it might be that 
> somebody "golden screwdriver'd " that transmitter into oblivion.
>
>   I am thinking about what audio amp to put in.  LM380?  TDA2030? I'd 
> like to get one clean watt out.  I have not populated a 24V regulator 
> yet.  As far as I can tell, that's only used for the audio amp.  So I 
> can choose the voltage.
>
>
>                      - Jerry, KF6VB
>
>
>
>
>
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