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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

Dave See <https://bama.edebris.com/download/hallicra/ht37/ht37.pdf> https://bama.edebris.com/download/hallicra/ht37/ht37_second_copy.pdf page PDf 8 I looked at 6-3-9 Power Supply. It mentions setting

Oh Don, It's not always about you...;-) or L26 The final tubes along with C68 and C80 which I don't think are going to be very happy with a 35% over voltage. The margins are beyond best practice. I

Dave, Perhaps you are aiming that at me. I am just looking in, and mostly still wondering why that caution {pause in STBY }was in the manual. I have to believe there is a reason why it says what it

Here is the tube specification: https://www.tubeampdoctor.com/media/pdf/92/f7/3b/6146a_b_rca.pdf Anecdotal comment but I seem to remember rumors about those who modified HV power to solid state

Halden, Russ too Re “just a tad above 1000 V in STBY mode.” I think I made a question comment on Hilden’s topic, saying that I could find no information at all for the conditions under which the

Halden.? The HT-37 came fitted with a grounded line cord.? I installed one in the hot side downstream of the fuse and one in the neutral.? They are 4A, 16 ohm limiters.? Mouser# 527-CL70 Russ

Hi Russ, The 750V marked on the schematic might represent the voltage during key-down.? The HV in my HT-37 with the original tube rectifiers is just a tad above 1000 V in STBY mode. What kind of

Thanks Dave. Will do that next.? The crystal is suspect, so will check for oscillation/frequency first. -- 73, Russ KW6T The cheap item is rarely the least expensive.

Good stuff, Walt.? The articles you posted on your site are helpful. Thank you. -- 73, Russ KW6T The cheap item is rarely the least expensive.

Don. The bleeders are the likely culprit, and the replacement capacitors may also have an effect.? Three 68uf 450V capacitors replaced the two 20uf at 600 V capacitors; about 22uf versus 10uf in the

Oh, after looking, the bleeder is rather too small to make that difference. Sent: Tuesday, August 13, 2024 12:31 PM To: [email protected] Subject: Re: [HallicraftersRadios] Re-membered