Help with mating an HP-23A power supply to the MT-1 Cheyenne

[AF9J]

Hi Everybody,

I've been working on the Cheyenne today.  So far it seems to be in OK shape.  More than anything else, it's dusty from a lack of use (I did some preliminary cleaning inside of it to get rid of the worst of the dust).  I've wired up the 6-pin Cinch Jones for the transmitter end.  Now I have to to wire up the 11 pin plug (thanks John for the plug! ) on the HP-23A end of things.   This is where it gets a little weird for me.  The Cheyenne is normally wired to work as a slave (powerwise) to the Commanche receiver.  Steps are listed for working around this, so you can use the Cheyenne with other receivers (basically you bridge between Pin 6 [which is a ground], and Pin 4 [which controls the power supply voltage]).

The 11 pins on the HP-23A are as follows:

Pin 1   -130V bias
Pin 2   Fil. Common
Pin 3   + LV
Pin 4   + HV
Pin 5   Not connected
Pin 6   12V filament voltage
Pin 7   Ground
Pin 8   6V filament voltage
Pin 9   AC switch
Pin 10  AC Common
Pin 11  Adjustable Bias

OK,  Now I know have to connect on the transmitter end from Pin 5 (the Filament) to Pin 6 on the HP-23A for filament power (no it's not Pin 8 like I expected, because checking my Cheyenne out, showed it was wired for 12V filament power [done by using a 5W, 11 ohm resisitor as a voltage divider {the manual shows how to wire it for either 6 or 12V filament voltage}]).  I know that Pin 1 (the 300V, Low Voltage supply) on the Cheyenne end, goes to Pin 3 on the HP-23A end.  I also know that Pin 2 (the 600V High Voltage supply for the 6146 final) on the Cheyenne, goes to Pin 4 on the HP-23. 

OK, now this is where I worry about making a visit to Zorchland. 

1.   I have TWO different ground points listed for the Cheyenne's pins.  Pin 3 and Pin 6.   I only have ONE ground shown on the  HP-23A (pin 7).  I'm not sure if one ground is for the filaments, and one ground is for the final.  So, I'm a bit leery about wiring both of them up to Pin 7 of the HP-23A power supply.   Is the one listed as Ground on the power supply for the filaments, and do I take the other ground to one of the bias pins on the power supply?

2.   The HP-23A does about 820V for its high voltage.  I was told that you can bring it down to 600V, by adjusting the bias control.  So, would I run one of the grounds, to Pin 11 on the HP-23A (the Adjustable Bias)?

3.  Pin 4 on the Cheyenne is shown as being the Power Supply Control line on the pin diagram on the back of the Cheyenne (so the Comanche can control ON/OFF power from the supply).  BUT, in the manual, it lists Pin 4 as being for a relay.  Do I just ignore Pin 4, or is it needed to run the internal antenna relay, and/or supply voltage for the receiver standby relay (in the receiver)?  If I can't ignore it, what pin do I wire it up to on the HP-23A power supply?

I know some of you have used Cheyennes in the past.  Maybe you've encountered these issues.  What did you do to resolve them?

Thanks for any input you can provide.

73,
Ellen - AF9J

[W1RKW]

Ellen,

1.  Pin 3 and Pin 6 are common to each other on the Cheyenne.  You can use either or both without zorching as far as ground goes.

2.  I downloaded the HP23A schematic.  Looking at it  I don't believe you will be able to lower the B+ per sè using the adjustable bias control.  Using that control may allow you to adjust the bias current to the 6146 allowing you to use the 800VDC B+.  And if that is the case you will need to modify the Cheyenne to run a bias line to the 6146 from the power supply unit.  Then you can use pin 3 or pin 6 as a dedicated bias pin by removing the ground connection at either one of those pins.  One or the other pin will then be ground only.   Someone will have to chime in on this one as I'm not sure exactly how to run the Cheyenne at 800VDC.

3.   The Cheyenne schematic shows both pin 4's on both connectors as being connected together with no other connections elsewhere within the rig. Also, the original power supply schematic appears to not use pin 4.  I don't know if this is a misprint or what. It doesn't make sense.  Yet this pin 4 connection is used to interface the RCVR to the XMTR.  The Commanche receiver schematic shows pin 4 as being the on-off switch via the audio level control.  Maybe one of my manuals are missing some information or I have an earlier Cheyenne in comparison to your Cheyenne.

I'm sure this can be done easily with the PS you have.  Just need the right info.
Bob

1.   I have TWO different ground points listed for the Cheyenne's pins.  Pin 3 and Pin 6.   I only have ONE ground shown on the  HP-23A (pin 7).  I'm not sure if one ground is for the filaments, and one ground is for the final.  So, I'm a bit leery about wiring both of them up to Pin 7 of the HP-23A power supply.   Is the one listed as Ground on the power supply for the filaments, and do I take the other ground to one of the bias pins on the power supply?

2.   The HP-23A does about 820V for its high voltage.  I was told that you can bring it down to 600V, by adjusting the bias control.  So, would I run one of the grounds, to Pin 11 on the HP-23A (the Adjustable Bias)?

3.  Pin 4 on the Cheyenne is shown as being the Power Supply Control line on the pin diagram on the back of the Cheyenne (so the Comanche can control ON/OFF power from the supply).  BUT, in the manual, it lists Pin 4 as being for a relay.  Do I just ignore Pin 4, or is it needed to run the internal antenna relay, and/or supply voltage for the receiver standby relay (in the receiver)?  If I can't ignore it, what pin do I wire it up to on the HP-23A power supply?

I know some of you have used Cheyennes in the past.  Maybe you've encountered these issues.  What did you do to resolve them?

Thanks for any input you can provide.

73,
Ellen - AF9J

[WQ9E]

Hi Ellen,

You might also want to download the schematic for the HP-20 "utility" supply which was designed for the mobile twins.  It uses a similar transformer to that of the HP-23A but derives both the high and medium voltage from a single winding.  What you might consider following is the way the voltage doubler is set up to provide 600 volts in this supply.  It uses a pair of smaller 40 uf capacitors as the input to the filter and then connects the 125 uf units through 100 ohm series resistors.  Although your HP-23A transformer voltage is a little higher than that of the HP-20, using the 2 stage filter with smaller input capacitors will yield a voltage far closer to the design value for the Cheyenne.

The previous poster's comments about bringing the variable bias voltage to the Cheyenne to compensate for increased final plate voltage is also very important to follow.

73, Rodger WQ9E

[AF9J]

OK, I have a thought.  I've used 6146Bs in in my Kenwood TS-820 at about 800 or 900V in the HV circuit. I have a couple of them laying around here.  If I remember rightly, the 6146B has about 40 or 50% higher plate dissipation power capability (and as a result, a bit more output power) than the 6146, or 6146A (my Cheyenne is using a 6146). Might it possibly just be easier to rebiase the Cheyenne for 800V, so I can run 6146Bs?  Besides, I could use more omph as it is, and the 6146B is a more common tube.

73,
Ellen - AF9J

[WQ9E]

Hi Ellen,

The 6146 itself should have no problem with 800 or so volts on the plate since the Cheyenne is controlled carrier AM so you won't have any plate voltage increase under modulation.  I don't have my Cheyenne schematic handy but I don't recall that the final plate voltage goes through any switches or relays so the usual suspects for breakdown under a slight voltage increase are not there.

There have been reports of problems with instability and neutralization problems when using the B or W variants of the 6146 in rigs designed for the original tube but I have never experienced any problem and I am using B's in one of my Valiants and W's (the vacuum tube not the dim bulb) in my other Valiant without any problems.

My reference to the HP-20 schematic was just if you wished to run the original voltage on your Cheyenne and I think that you will have no problem using the HP-23A as is as long as you do provide a bias adjustment.  I believe the Cheyenne was rated for 90 watts either phone or CW and you probably don't want to push that limit much due to heating inside the rig.  For future consideration, the 1 KW class of linear amplifiers (SB-200/HA-10/FL-2100B etc.) work great with controlled carrier AM rigs.

73, Rodger WQ9E

[WZ1M]

Could it be that the 820 volt supply is at no load and will drop to about 780 when under full load?

[WQ9E]

Actually closer to 750 under full load as I recall from my SB-102 but you are right Gary, I imagine about 780 under the lighter load of the Cheyenne.  Of course this is greatly dependent upon the health of the filter caps and the actual line voltage but still considerably higher than the ~600 volts originally specified for the Cheyenne.

Rodger WQ9E

[WU2D]

HI Ellen,

I agree.  I think the HP-23 will work great on that rig without fooling with it since it does not have the greatest regulation anyway. You may not need to fool with the bias at all. And try the 6146B - It will probably work great.

I used one of these supplies on my old NCX-3 that I had in college and it was solid, even when bad things happened like the main relay getting stuck!

Mike WU2D

[AF9J]

You guys are so cool!  So, in other words, I only need to connect up one of the grounds (I also noticed in the schematic that both grounds seemed to be common), to the HP-23A ground at Pin 7, the Low Voltage line to Pin 3, on the HP-23A, the High Voltage line to Pin 4 on the HP-23A, and the Filament line to Pin 8 on the HP-23A. Hmmmm, in other words I didn't need to solder up the other two lines (the one for theON/OFF control of the power supply from the  Comanche [which I don't have], and one of the gorunds)?

OH well, maybe I should clip those two wires short. I'm done with the transmitter end of the power cable.  I just need to finish up the power supply end.  BTW, yes, I've heard of issues with neutralizing 6146Bs and 6146Ws, with some rigs that were designed around the 6146 & 6146A. Well, it's late.  I'd better get some sleep.  Just one last time, I only need to hook up 4 of the 6 lines I soldered?  It may sound stupid, but I'm just trying to play it safe.  The last time I rushed through an electronics job, I made a mistake that was a bit of a hassle to repair.

73 & Good Night (4:30 AM comes early for me),
Ellen - AF9J

[w3jn]

As I've posted previously, I've had no problems whatsoever running a Cheyenne with a stock HP-23.

[AF9J]

Good morning John,

Did you only need to hook up 4 of the 6 wires that are ordinarily hooked up to the Cheyenne?

Ellen - AF9J
Half done with the power cable

[w3jn]

As I recall, 5 conductors.  Fil, bias, B+, final plate, and ground.  Some HP-23s have an on/off switch, others dont so you hafta short the 110 lines coming out of the PS (was meant so turning on the radio actually turned on the PS.  I wouldn't do this wiht the Cheyenne though).

[K1MVP]

  BTW, yes, I've heard of issues with neutralizing 6146Bs and 6146Ws, with some rigs that were designed around the 6146 & 6146A. Well, it's late.  

Hi Ellen,
I have had "issues" trying to neutralize 6146`s in an old Knight T-150 transmitter,--what a real "pain".
But then again, I had problems neutralizing my homebrew 6L6 xmtr,--ya never know.
                                               73, Rene, K1MVP

P.S, How is the "96" working out for you? 

[AF9J]

Good morning John,

I was wondering if the bias had anything to do with it.  My problem is that there is no specified bias line from the Cheyenne.  Here is the pin out from the Cheyenne power plug:

Pin 1 - 300V LV feed
Pin 2 - 600V High Voltage feed (from what everybody says I'm oK with the 820V no load off the HP-23A
Pin 3 - Ground
Pin 4 -Relay/On & Off power supply control feedthrough to the Comanche (to use it for On & Off power supply switching) NOT USED in my case.
Pin 5 - Filament Voltage (in my case 12V, since that's what it's wired for)
Pin 6 - Ground

First of all I assume I would hook up to the Adjustable Bias feed from the HP-23A.  But, what do I use to feed the bias?, one of the Grounds (since the Bias is basically nothing more than a DC offset from Ground anyway)?

73,
Ellen - AF9J

As I've posted previously, I've had no problems whatsoever running a Cheyenne with a stock HP-23.

[w3jn]

I thought the CHeyenne needed a bias supply.  Guess my memory isn't correct.  If it doesn't need it, don't connect it 

[AF9J]

Okee doke.  Thank you!  Well, back to work for me.  I'm going to finish wiring up Ms. Cheyenne after work.  Then it's smoke test time (sorry, but yours truly doesn't have a Variac).

73 & have a good day,
Ellen

I thought the CHeyenne needed a bias supply.  Guess my memory isn't correct.  If it doesn't need it, don't connect it 

[KB2WIG]

            "doesn't have a Variac)."    series up a 100 watt lamp in the 120 v line ...it will drop the voltage and also act as a fuse.....   its a little better than nothing.......  klc

[AF9J]

Hi Rene,

The SX-96 is The Bomb for me.  It hears AM so much better than the receiver in my FT-897D.  I would have never been able to check into the Midwest Vintage Net without it, two weeks ago.  It works great.  Thanks for selling it to me.

As for the 6146Bs - yeah, I'm aware of neutralization issues when using it with some of the older rigs from the 50s and early 60s.   It was an issue of discussion last year in the Kenwood Hybrids group I belong to.  Basically, the 6146B is markedly different from the 6146, and 6146A tubes.  So much so, that some Collins, and Heathkits have gone into runaway parasitics, and nuked themselves.  I guess I was hoping that with the B's higher plate dissipation power, I could weasel a few extra watts out of the Cheyenne.  I have two Chinese 6146Bs sitting around (that I got soaked for $55 from AES last year), that are basically useless in my Kenwood TS-820, due to the fact that its very high plate voltage (900 volts), literally caused the filaments to flash over, as soon as I turned them on, giving me the opportunity to make repairs in the High Voltage board.   But at the lower voltage the Cheyenne runs at, they may be useable.  If not, does anybody here have a use for them?

73,
Ellen - AF9J

  BTW, yes, I've heard of issues with neutralizing 6146Bs and 6146Ws, with some rigs that were designed around the 6146 & 6146A. Well, it's late.  

Hi Ellen,
I have had "issues" trying to neutralize 6146`s in an old Knight T-150 transmitter,--what a real "pain".
But then again, I had problems neutralizing my homebrew 6L6 xmtr,--ya never know.
                                               73, Rene, K1MVP

P.S, How is the "96" working out for you? 

[AF9J]

Yeah I have one of those.  I made it last year.  We use them in the Kenwood hybrids group to provide a load, and save the power transformer, while doing repairs.  I should have thought about using it.  Thanks for the reminder KC.

73,
Ellen - AF9J

            "doesn't have a Variac)."    series up a 100 watt lamp in the 120 v line ...it will drop the voltage and also act as a fuse.....   its a little better than nothing.......  klc

[W1RKW]

I use the ole light bulb in series trick for a lot of things, especially for troubleshooting and testing.  I have a collection of light bulb wattages for various situations.  My range is 25w to 200w depending on what I'm testing.  I start off small and work up to big to a certain point.  It's mostly feel.

Also using other 6146's other than the ones designed for the circuit can also introduce parasitics besides neutralization problems.

Yeah I have one of those.  I made it last year.  We use them in the Kenwood hybrids group to provide a load, and save the power transformer, while doing repairs.  I should have thought about using it.  Thanks for the reminder KC.

73,
Ellen - AF9J

            "doesn't have a Variac)."    series up a 100 watt lamp in the 120 v line ...it will drop the voltage and also act as a fuse.....   its a little better than nothing.......  klc

[The Slab Bacon]

FWIW:  6146, 6146A, and 6146W are all interchangable and will work just fine. However the 6146B is somewhat a different animal. It not only has a little more dissipation, but it is designed a little differently.

It is really best suited for AB1 service as a leenyour amplifryer for SSB service. It has a different screen grid structure and wants a higher screen voltage to produce a little more gain in amplifier service with less drive. I have also seen them used as class C amplifiers and drivers that were NOT modulated. they do have different interelectrode capacitance values than the standard versions. This may explain some of the neutralizing / parasitic problems.

"B"s will work fine in some AM rigs and not in others. It is totally dependent on the final circuit and operating parameters of the individual transmitter.

                                          The Slab Bacon

[AF9J]

Cool Frank,

I'll have to check out the schematic to see.  But in the meantime, if anybody has a need, or a use for a couple of Chinese 6146Ws badged as Penta Labs, let me know.   As of right now, the tubes have been sitting in their boxes for a year, gathering dust.

73,
Ellen - AF9J

[W1RKW]

Then there's the ole elusive 6293.

Ellen, have you been able to put the fire to the wire yet?

[The Slab Bacon]

Then there's the ole elusive 6293.

Ah Yes........... the good old pulse rated 6146 which will usually work just about anywhere you'd use a regular 6146, but no one knows about them and you can usually find them for $1 at hamfests

[AF9J]

Hi Bob,

I just have to finish soldering up the power supply end of the cable.  I was going to do it yesterday, but I had such a lousy day (frankly the whole week was lousy), and I was so burned out, I just vegged out, and went to bed early.  I didn't get any further than stripping the wires.  I plan on doing it tonight.  I took tomorrow as a vacation day, so hopefully (if everything behaves), I'll be able to give it a test run tomorrow.  I've heard of the 6293.  Becuse it's meant for pulse service, and all of the stress pulse transients can cuase, it's supposed to VERY sturdy.  Oh, and don't for get the 12V version - the 6883.  There are suppsoed to be a ton of them around from the old Motorola Motracs, going for peanuts.

73,
Ellen - AF9J

Then there's the ole elusive 6293.

Ellen, have you been able to put the fire to the wire yet?