Questions on ARRL 813 Rig

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N3DRB The Derb:
Also, in all your HV supplies, consider the use of a "safety bleeder" running offa yer B+ bleeder resistor. In case the big bleeder opens up and you go in the rig to find out what is wrong, it could save your life. Something like a 2 meg 2 watt~3watt ( use ohms law here) to ground will slowly drain the voltage to ground without any effects. There's formula to figure out best values but I dont remember it. Use a decent margin of safety (double the wattage 'required' is my rule) because teh resistance is so high, you dont need much power handling.

Carl WA1KPD:
Derb,
Thanks for the input. I planned to start with the VFO first and work my way up to the 6146.I only need 400V up to that point and am using a bench supply for that. Once I have that tamed and running I will build up the permanent supply and then go back and rebuild the HV supply I have courtesy of a local. Good idea on the extra bleeder. I'm more then a little concerned about the HV. I generally stay with rigs 100 watts or less for that reason

I have the parts for the modulator from 10 years of collecting- including the iron which I hope is good. For a speech amp I have a really buzzardly HB one from the 40s. It uses some 2A3s so I may convert it to 6L6s given the current cost of a 2A3.

Mike,
I'll keep an eye out for the B&W. If not when I get to that point I have a fair amount of stock some big caps and a good GDO. I appreciate the info.

Pete,
Appreciate the info. I had most of the articles except the particular HB one. It is nice because it calls out in more detail the parts locations. Would have gotten there anyway, just saves time.

Tnx all
KPD

N3DRB The Derb:
6L6's make crap driver tubes for audio unless you bring the plate impedance way down. Triode connected they are teh ok. I used 2A3's in my HB rig and they just drive the hell out of almost any mod tube you will use. They could pin a 500ma meter on a whistle in my mod deck.

I think the chinese 2A3's are ok quality these days. I fixed the bias on mine at -62 volts with a zener. on of the few modern concessions I made on my HB rig. No 2 volt fil transformer, use 6B4G's, just like a 2a3 but with a 6 volt fil. maybe confusing it with a 9pin mini tube. PM a message to N3LHB and ask him what driver tubes he used on his HB rib when he lived in Carlisle PA. I have no reference material here, not even a arrl handbook.

use audio toobs fer audio. RF toobs fer RF. I sez.

of course, if you never step out of ab1 operation, it's not as important. But the second you deliver power onward up the chain and go into ab2 mode, the 6L6's will turn to crap.

KL7OF:
6L6's will work very  well for your speech amp if you give them some neg feedback...... that will lower the output resistance....... look at the arrl 6L6 speech amp for the values of coupling cap and feedback resistor. It is in the handbooks from about 1947 on.  I have built several of them and they  work .  Very cool rig... good luck  I hope to hear you when you get it going..

WBear2GCR:
Before you neuter the bandswitch - check to see if it has an extra contact! or a space for an extra contact!! Then just move the stop and add 160!

It's often possible to "borrow" a contact or two off unused contact positions on the switch, sometimes the mfr actually provides "unused" contacts intended to have the rivet drilled, and the contact used for field repair - or you can scare up another switch with a suitable contact and add it in.

You could consider adding in the 160m positions by pulling the 10m contacts for now, and moving them to the 160 position if that is applicable in your situation - go back and fix the 10m spot later when the contacts appear at NEARFEST or someplace like that.

By the way, REALLLY nice find!

         _-_-bear

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