Gates BC1T Initial Power Up

[KA3EKH]

Don’t worry about the 833 turning red, I have abused them to no end in Ham and broadcast service and never fail to be amazed how durable they are. At full power it’s not unusual for the PA tubes to glow if the transmitter is not tuned right. I run a signal 833 in my RCA for the PA at 1.5 kV @ 0.32 and if the transmitter is out of resonance it will turn the tube a little red. Also keep in mind that you can pull the two modulators out and just run the PA tubes by themselves for doing the RF work. The modulators will have individual bias pots for balancing the modulator but the PA tubes just have one pot that controls the bias to both of them, remember the PA is not push pull but just two tubes in parallel.

[John K5PRO]

Be aware that it has direct coupled 807 cathode followers as audio drivers for the modulator 833s. I remember seeing an 833 turning white hot and sucking a hole in the glass when the bias was screwed up due to 807 issue.

[ka4koe]

No, a friend gave me a Fluke 114 for Christmas. Notice I'm not holding the red meter when power is applied. In any event, it is likely in the landfill at this time.

[flintstone mop]

Hi,

Speaking of DVM meters, one of the more accurate and survivable meters I have used is the Southwire 11060S.

I think I bought it at Lowes.

Phil - AC0OB

Maybe Phil has a line on a DVM that can deal with voltages close to or over 600vdc. I blew out many of those DVM's Even my Fluke......I use an RCA Voltohmist for stuff getting close to 1KV VDC.

Fred

[K1JJ]

Be aware that it has direct coupled 807 cathode followers as audio drivers for the modulator 833s. I remember seeing an 833 turning white hot and sucking a hole in the glass when the bias was screwed up due to 807 issue.

I've had a similar experience.   833As certainly are not as rugged as 4-1000As in modulator service.  I've made mistakes with 4-1000As at 3500V and they survived easily.  But I have a pair of 833As with popped  25 cent  sized holes in the plates when they got away from me at the same voltage.

Your 1.5 KV is tame and should be fine.  833As are cool looking tubes, but I now always run them below 3KV and use some shut down protection to be sure. I use a Hall effect device in the cathodes of all my big power tubes as a fail safe. In fact the 4-1000As also have them in the screen and grid circuits for protection.  It's easy to make a big mistake when we have been away from the rig for a while and forget the rig procedures. Don't axe me how I know this...  

T

[DMOD]

Hi,

Speaking of DVM meters, one of the more accurate and survivable meters I have used is the Southwire 11060S.

I think I bought it at Lowes.

Phil - AC0OB

Maybe Phil has a line on a DVM that can deal with voltages close to or over 600vdc. I blew out many of those DVM's Even my Fluke......I use an RCA Voltohmist for stuff getting close to 1KV VDC.

Fred

The meter I mentioned has 1kV capabilities in both AC and DC modes.

I use a X100 probe with the meter for measurements over 1kV.

Phil - AC0OB