B&W 5100B

[K3ZW]

Hi All

I am looking for users of B&W 5100B's to get tips, advice and mod/improvement ifo.  I also have a Globe Scout 40A & Scout Deluxe.
I have been a Ham for over 30 years and have been inactive for the last 15. I am getting back into the hobby. I love working on the old tube gear.

[KA2DZT]

Welcome to the AM Forum.

There are folks on here that have 5100Bs.  I'm sure they'll be along soon with some help.

Fred

[Jim, W5JO]

You won't have to do much.  Replace all electrolytic caps and remove the couplate in the audio section.  Increase the coupling cap by X 2 is about you really need do.  Don't try to hot rod it, the iron isn't big enough.

[K3ZW]

I took the 5100B apart and cleaned up the chassis, replaced the electrolytics & replaced the bias diode. My 5100B has solid state plug in replacedments for the 5R4s & 5u4. I have done no audio mods. I have operated it into a dummy load for short periods. It seems to tune up OK. Does the meter read actual current in the exciter position or is it divide by 10? If it is direct read, my exciter ( screen current) is too high even with the exciter control fully CCW. I am thinking the bias may be set wrong. The transmitter had a 6146B & a 6146W in the PA. I replaced them with new NOS straight 6146's

[Jim, W5JO]

The meter is scaled for plate and screen.  It has been a while but I think the problem you reference may be related to 40 meters.  The manual said to detune the exciter to keep the current proper.

[K3ZW]

The only technical data I have is what I got from the BAMA site. My high screen current is on all bands.

[Jim, W5JO]

You need to check the screen shunt resistor.  I believe it is R 46.

[K3ZW]

I have the BAMA prints for the 5100B. All the resistors are Rxxx( 3 digits ) I did the Bias adjustment proceedure. R514 is pegged to get the resting current back to 55 ma. and the exciter contol has no effect on the bias if you move it either side of 1/3.

I read the Service notes micellaneous, it reads that the full scale deflection of the meter is 40 mils in the grid position. the notes are refering to a "5100" not a 5100B. if this is true for my 5100b, I dont think I have a problem. It would make sense to divide a meter to read screen current since it is a much lower value.

[Jim, W5JO]

Seems the plate shunt is 40 ohms and the screen is 400 or some such.  It has been a while since I had one but shunts are tied to the switch, the schematic is in the middle of the diagram.  The physical location is on the wafer.  The difference between the plate and screen is 10.

[K1ZJH]

ZedW,

I have two B&W 5100 transmitters, and a Globe 45 with a VF-1 Vee-F-Oooo.

I'm just setting up a new station to incoporate the AM and vintage equipment.
Including an Old Buzzard 110' dipole feed with 6" open wire.  RXs on the AM
side will be a SX-42 and SX-28 with a Signal Slicer.

One thing to check is the filament dropping resistor on the 6U8A audio tube,
they are known to go up in value. I'd suggest going over to a metal oxide
type to prevent future problems.

Mark, K3SMB has a good website with B&W 5100 information.

Pete  k1zjh

[K3ZW]

Hi Pete

Sounds like a nice setup. My vintage receiver compliment is an HQ-129X, HQ-100 , Drake 2B and a Lafayette( Laughing Idiot ) HA-63.  I want to pair the 5100B with the HQ-129X.
I have the 5100b running with the HA-63 right now . I recapped & aligned the HQ-129X, Gave it a new front pannel and Knobs.  I am also repainting the cabinet. Crinkle finish of course. The HQ-100 is on a shelf collecting dust as I have no  more space to set it up.
I have the Drake 2B set up. Sounds great on SSB & CW. I dont like the audo on AM. The Hammarlunds and even the Lafayette sound better on AM



 My antennas are a crooked G5RV. Had to be crooked to fit on the small city lot where my home is. And a 14BTV verticle needing of more radials.

My Father is a ham. W3PZC is his call. He has given me all of his almost 70 year  collection of radio parts & tubes. Found 3 new RCA 6AQ5's. They are in the 5100B now.


I

[Pete, WA2CWA]

I read the Service notes micellaneous, it reads that the full scale deflection of the meter is 40 mils in the grid position. the notes are refering to a "5100" not a 5100B. if this is true for my 5100b, I dont think I have a problem. It would make sense to divide a meter to read screen current since it is a much lower value.

FYI:
There are Service Notes (Addenda) for the 5100B and there are Service Notes (Addenda) for the 5100. In reviewing, the only pages that are the same for both sets of notes are the TVI pages, Sub-Harmonic Radiation pages, and the Filter Network page. There are numerous differences between both rigs.

[K3ZW]

Hi Pete

I have not been able to find 5100B adenda at the BAMA site. I have the 5100 info.

[K3ZW]

What should my wattmeter read on my 5100B on AM with no audio dead carrier ??

[Pete, WA2CWA]

Depending on the plate current, plate voltage, condition of the final and driver tubes, overall efficiency of the driver and final circuitry and components, accuracy of the wattmeter, non perfect match, and maybe a few other parameters, probably roughly somewhere between 85 and 110 watts depending on the frequency of operation.

[K3ZW]

Hi Pete

I want to do a smoke test. 5 minutes dead carrier into a dummy at 90 watts on 75 meters should be enough. I installed a couple NOS JAN 6146'S in the final.

Thanks