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My Viking Valiant is probably a 1956 vintage transmitter. I am thinking that if,? in 68 years,? the "Bong" didn't hurt anything, it probably never will. Tom Raush W8JI designed most or all the

Halden, good information. I have not yet tried to understand the finals, bias etc, but I guess you are saying when going to STBY it takes a bit of time to unload the power draw, and it takes longer

Hi Don, Yep, the filaments are still loading the transformer so the voltage on one winding shouldn't go haywire by itself. You ask the very important question:? "does it?"? I actually have the

Hi Halden, I’m blue inserted in your original black I noted your idea in the "Re-membered (new to me) HT-37" thread about turning the transmitter off suddenly, possibly leaving some current in L26

Thanks Halden. I can't take credit for the inrush current limiter idea.? Rodger SIngley, WQ9E brought this up in another forum, and also referred to an article in Electric Radio by Jim Garland,

Hi Don, I noted your idea in the "Re-membered (new to me) HT-37" thread about turning the transmitter off suddenly, possibly leaving some current in L26 with no place to go.? At first I was hopeful

OK then, Install an inexpensive delay relay and never worry again about the mythical pause delay off training. Just ram that switch to the OFF position and let the trusted delay board keep the rig in

Hi Paul, my emails inbox is quiet today.. so.. RE “Jim also mentioned the mechanics of the HT-37’s Operation switch. I’m glad someone finally mentioned it as a possible root (or contributing)

Jim, Re your “I would think that one would have to see what the OPERATIONS switch is doing in those first three positions. Based on the manual this seem a most obvious place to begin. Thanks to

PaulI see your point about the 516F-2.? What I had in mind was the KWT-6 which is also a commercial designation and it's high voltage power supply of 2kv @ 500 mA.? AFAIK, this is also a 1958-9

“Other manufacturers, like Collins,? did use them in this same era since cost was a secondary or even lower concern to performance and reliability for Collins equipment.” The Collins 516F-2 power

To put this all in perspective: both cost and most-bang-for-the-buck were the driving forces in hallicrafters designs.? To address the question about the HT-37 design, hallicrafters engineers would

Agreed. Hoping to learn more here everyday as well. Best 73, -- Russ KW6T The cheap item is rarely the least expensive.

Ed, re my “designed to unload into the higher voltage region typical of capacitor input filters” Yes the HHV has an input choke of 8 Henrys. What I said poorly I guess is that when it has little

Good points Russ. But to tell you my subjective opinion of one... A plate supply that swings 350 volt when keyed without drive is a garbage power supply. If that happened on a screen supply as well

Dave, WA3GIN. Thank you for your comments. First off, I am not an engineer and have never played on TV; however, I also believe the engineers in the day knew what they were doing.? I also believe in

Did just recheck and yes, there is a capacitor at the input and then the swinging choke. When I built my rig we started with the semiconductor diode bridge and down the road I realized I did not need

The HT-37 as built did not have a capacitive input filter. There is a swinging choke at the input which was commonly used with tube rectifiers. Ed, WA9GQK

Thanks Don, I couldn't find the test in the file links provided. No matter. It's an interesting comment. I presume just another effort by the engineers to do best effort to increase longevity of the

Dave and all, I checked the crystals in circuit.? Taking the signal at the test point.? Both the 25 and 32 MHz crystals are oscillating; the 21.5 MHz crystal is not.? Just for grins, I plugged in a