[Johnson] Ranger 1 Turbo Modulator Instability

[David Harmon]

The first thing I would do is tear that 'amplifier' out of the D-104 and
wire the cartridge straight through so it is hot at all times.
You don't want to switch the mic cartridge because it for sure cause a pop
or noise on the audio.
At the least...this will ensure that the amplifier in the base is not
affecting the audio quality assuming the cartridge is still good.
I have had great success with the D-104 and you want to be sure to have the
mic impedance in the ballpark....
The resistors in the grid of the mic amp in the rig should be much higher
than original but they probably already are with the Turbo mod.

You can try unplugging the mic from the rig and use a cliplead to key the
thing to see if the problem is still there...I bet it will be.
Possibly a relay contact is mis-timed...ie...opens or closes too early or
too late....


73

David Harmon
K6XYZ
Sperry, OK


-----Original Message-----
From: johnson-bounces at mailman.qth.net
[mailto:johnson-bounces at mailman.qth.net] On Behalf Of Kenneth Goodwin
Sent: Tuesday, July 17, 2018 5:10 PM
To: johnson at mailman.qth.net
Subject: [Johnson] Ranger 1 Turbo Modulator Instability

With the Ranger's audio setting above 9 o'clock, I get a full peg spike in
the modulator plate current about 1 second after depressing the
push-to-talk. (Turbo Ranger mods by WA1HLR, W3AM, W4PNY) This lasts for 0.25
seconds (stops as soon as it begins).  No spike with Audio at 8 o'clock and
lower where the current spike increases from the 8 to 9 o'clock audio
settings.  I thought it might be the amplified D-104 (T-UG8) but I don't see
any prob with the D-104 when hooked to another rig.  I don't see it when
engaging the phone mode with just the push-to-talk when the mic audio input
into the female mic connector is open, regardless of the Ranger's audio
setting.  See the same modulator plate current spike in the Tune mode
(modulator circuit is engaged but not the finals).  I suspect it is an
interaction between the Ranger and the amplified D-104 or an instability in
the 6550 modulator circuit. I can operationally work around but seeing the
6550's plate current peg for 0.25 seconds is disconcerting.  I need to go
back and see if the power output level circuitry (modification) might be the
source since I have it set to about 20 watts output.  Will try it with full
power and as soon as I get a mic connector, I will try a different Hi-Z
microphone.  Any thoughts on what I should look for to solve the high plate
current spike?  Ken K5RG

 

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