MH conversion lamps and converting HPS ballasts to run MH

[Al B. Fuct]

I've vegged my mums under a 400HPS for many years. Works fine. Not sure I should have tried to fix something that wasn't broken, but there you go, eh? The HPS was a couple of years old and due for renewal.

 

Bought a 400W MH>HPS retrofit lamp and ran it for 2 weeks beginning immediately after I did a batch of cuttings off the mums. The mums usually recover fully within 15 days under the 400HPS- they have to be cut back or they're growing into the light, about 30-odd inches above the medium surfaces.

 

Under the MH conversion lamp, the mother plants took a full week longer to recover and even then were about 6" shorter than 15 days under the 400HPS. Considering I run a continuous harvest SoG op, this throws the sked way out of whack. I cut very tall clones, which suit the zero-veg-time SoG environment. HPS is known to cause a bit of stretch when used for vegging, but when cutting tall clones, this is a boon, not a bother.

 

So, I switched back to the 400HPS. Since I picked up a lux meter a few weeks ago, I measured the output of the MH conversion vs the 400HPS, knowing that this particular HPS tube is really quite tired and due for replacement. The 400MH conversion lamp was only putting out about 65% of the output level of the ancient 400HPS.

 

So... why might this be?

 

I've already had a problem with some 1000W replacement lamps that were branded the same as this MH conversion (hydro shop is importing lamps from China and house-brand-naming them). The cheap Chinese 1000s only put out 20% of some 2+ yr old GE LucaGrow 1000s!

 

Could the MH conv lamp be suffering from cheap Chinese syndrome?

 

Are there better MH conversion lamps out there which will keep up with the luminous output of an HPS?

 

Are there losses inherent in making a MH lamp that will cope with HPS control gear?

 

How about I just remove the igniter from the 400HPS ballast (or add a switch to remove it from the ckt when using MH) and get a 400MH for it?

 

Is 400W a standard value for MH lamps? I recall seeing odd std figures like 175W for MH lamps.

 

Thorts?

 

Thanx.

[loylty gets u nothing]

i use a 400w conversion bulb for veg

i use a phillips 1 HPT-I

and im trialling a new 600w conversion bulb

from growlush,very white in colour

ive had the brand venture just clean stop workin on me..

and another similar to the chinese 1s u speak work for a week

then die

imo stick with the brands that focus on this style of lighting

and have an actual lumen output to compare to

all the best

id love a lux meter ya lucky bugger

bil

[Al B. Fuct]

id love a lux meter ya lucky bugger

 

Found mine in the discontinued bin a few weeks ago at a Bunnings. Call a few and see if there are any left. I paid $20 for mine.

 

So, is there anything more to making an HPS ballast run a standard MH other than removing the igniter? Does the cap need to be relocated?

[loylty gets u nothing]

i wouldnt have a clue

but it seems viable with the ignitor being in the bulb

wouldnt like to be there if she went pear shaped..

imo just pick yaself up a fair dinkum 400w M/H ballast

wat 90$ max save any future dramas

and also itll be new so many life in it yet

all the best

bil

[Al B. Fuct]

wouldnt like to be there if she went pear shaped..

 

shh.... that's wot fuses are for. Not too dangerous to be in the same room when a 5A fuse pops.

 

imo just pick yaself up a fair dinkum 400w M/H ballast

wat 90$ max save any future dramas

and also itll be new so many life in it yet

 

Keeping in mind that I'm a bit of a techie, if 10 minutes worth of modification is all I need to do, I'm halfway home. 10cm of rosin core solder is a lot cheaper than $90. I have a couple of spare 400HPS ballasts that are in fine shape.

 

Seems to me that a ballast is essentially a series ckt- mainly an inductor and an HID lamp with a capacitor thrown in somewhere just for kicks. The ballast's inductor is going to limit current to 400W- and if the MH doesn't need the ignitor and I remove it from the ckt (or add a switch to disable it), it shouldn't matter whether the lamp is an HPS or MH.

 

Anyone have any firm info regarding such a ballast mod?

[Frazz]

Last year i bought a 400w MH globe to run on HPS ballast , called Grow Good , or Grow Fast , Nu Grow? el cheepo.... i have no good memory but it was some chinese manufactured globe ... was only good for about 4-6weeks, came from pet shop boys Hydro ...

 

[Al B. Fuct]

Seems there's a bit more to it than just lopping the igniter out of the ckt:

 

Switchable HPS/MH Ballasts;

 

Recently introduced, these ballasts allow the use of both HPS and MH bulbs. They operate by simply switching the HPS igniter out of the circuit. Generally, the switchable ballast consists of an HPS ballast with a switchable igniter. When an HPS bulb is used, the igniter is switched into the circuit. When an MH bulb is used, the igniter is switched off or out of the circuit. Although switchable ballast technology is simple, the user should exercise extreme caution because of the different voltages that HPS and MH bulbs operate on.

 

Safety First:

 

We do not recommend the use of simple, home-brewed and simple switchable ballasts that only take the HPS igniter out of circuit when in MH mode. Some readers may have the inclination to "make" switchable ballasts using a 1,000 watt HPS ballast core. Remember, HPS and MH bulbs have different operating voltages and electrical characteristics, this makes them incompatible with the idea of a simple switchable ballast. On certain occasions the MH bulbs have been known to rupture and explode. Although you may know someone who has successfully deployed simple switchable 1,000-watt ballast, the stress that this system places on the MH bulb can cause rapid breakdown, bulb integrity failure and fire. If you must use a single ballast for powering both MH and HPS bulbs, choose an HPS ballast with HPS main lights (Bloom/Flower) and purchase a few MH conversion bulbs to cover your vegetative cycle. Additionally with our new CFL and HPS balanced spectrum technology, there is a reduced requirement for MH lights if the vegetative cycle is short, i.e. in sea-of-green applications.