Ranger PTT Mod

[W3UTD]

Gathering parts for this and need a sanity check on two of the parts

Relay DPDT, Mouser Part #:  655-K10P-11D15-110

4.7mH VHF Choke (this one I'm really not sure about)  Mouser Part #:       434-02-472J

Any help would be great, thanks.




All right, that's not getting me anywhere ...

So ...

What is the easiest way to get PTT into a Ranger?  Easiest, not best or coolest, easiest ... for a newbie like me

[W3UTD]

with parts I can find 

[WA5VGO]

Tie onto the filament line with a diode and filter capacitor. Use a relay with a 6 VDC coil.

73,
Darrell

[W3UTD]

Darrell,

Thanks for the words, however, I'm a newbie with tube transmitters, I need more hand holding (details), so to speak.

[KB2WIG]

Check this one out  ... then maybee some hand holding help....

http://www.amwindow.org/tech/htm/rangptt.htm

klc

[n7ioh]

I don't know if this would make it any easier but take a look at it.  You can also contact the seller for more specific information about hooking it up to your ranger. 
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310196085562&ssPageName=STRK:MEWAX:VRI

It looks good and the parts from what I can tell are good quality stuff.

Al, n7ioh

[W3GMS]

The ebay link above it not what you want.  What that is is a transmit receiver antenna relay scheme with muting contacts.  You can use that but you will still have to turn the function switch on the Ranger to go from transmit to receive. 

The problem with the Johnson factory mod is that the standby power is really high.  Tim, WA1HLR scheme that was attached to this thread is a much more efficient scheme.  All you really need is a 4 pole double throw relay.  The 4 functions that you need to switch are the screen voltage on the final, the screen voltage on the modulators, the 115 to the xtal socket on the back of the rig that is used to enable the TR relay and lastly enable the oscillator by grounding the key line.  The schematic above pretty well shows what needs to be done.  I have used Tim's scheme for years and it works very well. 

If you find the factory one easier then maybe you want to try that one, but I like Tim's scheme much better. 

Good luck with your project.

Joe, W3GMS         

[WQ9E]

Like Joe I used a version of Tim's modification.  I used a 6 volt relay powered from a rectifier fed by the 5 volt rectifier filament winding.  I went with SS rectifiers so that winding was no longer in use anyway.

The Johnson factory mod is simple but it leaves a lot to be desired.  The Ranger has a lot going on in a small box and it will run extremely hot with the factory suggested PTT system. 

Rodger WQ9E

[W3UTD]

Since I have replaced all the caps and out of spec resistors, and since I don't expect to be running this rig every day, I think I'll go with the factory mod.

[K5UJ]

Like Joe I used a version of Tim's modification.  I used a 6 volt relay powered from a rectifier fed by the 5 volt rectifier filament winding.  I went with SS rectifiers so that winding was no longer in use anyway.

Hi Rodger,

I don't understand this statement.  I understand you rectified the ac on the secondary of the filament supply transformer.  I don't understand how solid stating the filament supply obviated the need for the supply transformer secondary winding.  Also, I don't understand why the filament supply can't be AC.   This must be a stupid question but I'm still trying to figure this stuff out as well.  I think the filaments on the tube gear I have and am familiar with take the filament voltage right off a transformer winding.  Maybe that's only okay if you are dealing with triode RF amps or tubes that have a separate heater and cathode?

Rob

[WQ9E]

Hi Rob,

Sorry, I guess I didn't word this clearly.

Because I am using solid state rectifiers, the separate winding that supplies 5 volts AC to the tube rectifier was no longer used.  So that is the winding I used to rectify and supply 6 volts for the PTT relay.  Others use the winding to "buck" the transformer primary to lower the secondary voltages.

The regular filament supply is still 6.3 volts AC which is fine for everything we do in radio.  About the only time you see DC used on tubes with indirectly heated cathodes is when all hum must be removed.  For example, Tektronix runs the filaments in the vertical plug-ins for their 500 series lab scopes in series across one of the regulated B+ supplies.  Some of the high end tube preamps also use DC on the filaments.

But certainly there is no need to do this for the Ranger and filament life is better on AC than DC.

Rodger

quote author=K5UJ link=topic=22709.msg165721#msg165721 date=1264379503]

Like Joe I used a version of Tim's modification.  I used a 6 volt relay powered from a rectifier fed by the 5 volt rectifier filament winding.  I went with SS rectifiers so that winding was no longer in use anyway.

Hi Rodger,

I don't understand this statement.  I understand you rectified the ac on the secondary of the filament supply transformer.  I don't understand how solid stating the filament supply obviated the need for the supply transformer secondary winding.  Also, I don't understand why the filament supply can't be AC.   This must be a stupid question but I'm still trying to figure this stuff out as well.  I think the filaments on the tube gear I have and am familiar with take the filament voltage right off a transformer winding.  Maybe that's only okay if you are dealing with triode RF amps or tubes that have a separate heater and cathode?

Rob
[/quote]

[K5UJ]

Because I am using solid state rectifiers, the separate winding that supplies 5 volts AC to the tube rectifier was no longer used.  So that is the winding I used to rectify and supply 6 volts for the PTT relay.  Others use the winding to "buck" the transformer primary to lower the secondary voltages.

No, I still am not getting it because I probably did not ask the right question.  I'll try again.  If you are not using the filament supply secondary for the s.s. filament supply rectifiers, where are you getting the a.c. to rectify for the filaments? 

Here's the picture from what you wrote.  You had a tube rectifying the filament AC.  you solid stated that.  somehow you no longer need the 5 or 6 v. AC to rectify.  Where else do you get the AC for the s.s. rectifiers to rectify?  Or, was the filament supply AC just getting the tube rectifier filament hot enough for thermal emission?  Why would a h.v. tube rectifier need a filament supply?  wouldn't the h.v. be enough to light up the filament?

(We'll get to how on earth this low voltage can be used with a buck transformer later as that sounds even more bizarre.)

thanks,

Rob

[WQ9E]

Rob,

The power transformer in the Ranger has a 5 volt winding (insulated for HV) that is only used to heat the filamentary cathode of the 5R4 rectifier tube.  In addition, it has a separate 6.3 volt winding for the filaments of all of the regular (indirectly heated cathode) tubes, and a separate HV winding which has additional taps of that winding for the low B+ and the bias rectifiers that are applied to the plates of those tube type rectifiers.  

High voltage, low voltage, and bias voltages are all supplied by rectifying and filtering the potential from the various taps of the high voltage secondary.

In the standard Ranger, no filament voltage is rectified.  There are rectifiers for the HV, LV, and bias voltages.  In my Ranger, I used solid state rectifiers to replace the 5R4 tube type high voltage rectifier and with the tube removed the 5 volt winding, which was used ONLY for the 5R4 heated cathode, is now available for other use.  

You definitely don't want to apply high voltage to a filament unless you desire a bright flashing light followed by a smoked transformer

If the 5 volt secondary winding is connected out of phase in series with the primary it will "buck" the primary effectively reducing the primary voltage and thus the secondary voltage.  So if you have 120 volts applied to the primary but connect the 5 volt secondary in series but out of phase with the primary winding then the effective primary voltage is now roughly 115 volts and the secondary voltages will be reduced accordingly.  If connected in phase then the secondary voltages will be increased.

I hope this helps Rob.  This is the sort of thing that is easy to clarify using a telephone in "full duplex" mode but far more difficult via email or bulletin boards.  

Rodger

No, I still am not getting it because I probably did not ask the right question.  I'll try again.  If you are not using the filament supply secondary for the s.s. filament supply rectifiers, where are you getting the a.c. to rectify for the filaments?  

Here's the picture from what you wrote.  You had a tube rectifying the filament AC.  you solid stated that.  somehow you no longer need the 5 or 6 v. AC to rectify.  Where else do you get the AC for the s.s. rectifiers to rectify?  Or, was the filament supply AC just getting the tube rectifier filament hot enough for thermal emission?  Why would a h.v. tube rectifier need a filament supply?  wouldn't the h.v. be enough to light up the filament?

(We'll get to how on earth this low voltage can be used with a buck transformer later as that sounds even more bizarre.)

thanks,

Rob

[K5UJ]

Hmmm.  All these diode rectifier tubes must have indirectly heated cathodes.  the cathodes must be excited to a state where the electrons in higher orbitals in the alloy lattice are free to leave so current can flow from the anode to the cathode.  I see.  So indirect heating isolates the excitation energy from the rectification function of the cathode.    Okay, it takes me a while but I eventually get it.  Okay on using the 5 v. winding to buck the primary v.  There are two things that come to mind with that practice.  First, it seems dangerous in that the primary supply AC service voltage is, I would think, not sufficiently isolated from the secondary h.v.
Secondly, how does one reverse the phase of the 5 v. winding?

thanks

Rob

[WQ9E]

Rob,

Actually I think directly heated cathode structures are more common in rectifier tubes thus the need for a separate cathode/heater winding for the rectifier.  It is difficult to use an indirectly heated cathode for a rectifier because the insulation between the heater and cathode must be sufficient for the HV DC that is present on the cathode. 

Smaller indirectly heated cathode rectifiers were released; probably mostly as a cost savings measure for cheaper receivers so that the transformer wouldn't require a separate heater winding just for the rectifier.

Insulation is really not a problem when using the 5 volt winding to "buck" the primary because it is insulated for the full B+ that appears on that winding plus a safety factor.  Whether the 5 volt winding aids or bucks the primary depends upon how it is connected.  The two are put in series and if the voltage on the remaining secondary windings increase then you connect the opposite lead of the 5 volt winding to the primary winding.

Hmmm.  All these diode rectifier tubes must have indirectly heated cathodes.  the cathodes must be excited to a state where the electrons in higher orbitals in the alloy lattice are free to leave so current can flow from the anode to the cathode.  I see.  So indirect heating isolates the excitation energy from the rectification function of the cathode.    Okay, it takes me a while but I eventually get it.  Okay on using the 5 v. winding to buck the primary v.  There are two things that come to mind with that practice.  First, it seems dangerous in that the primary supply AC service voltage is, I would think, not sufficiently isolated from the secondary h.v.
Secondly, how does one reverse the phase of the 5 v. winding?

thanks

Rob

[K5UJ]

Okay, maybe you only want a separate heater element when the heater voltage AC RMS is very close to being what the rectified voltage will be?  I've forgotten why we're trying to come up with 6 v. DC now anyway. 

[WA1HZK]

http://amfone.net/ECSound/index.htm

Simple really.
I have the drawings posted here.
Keith