¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. HallicraftersRadios
  2. Messages
Expanded Topics Messages
Date
Re: S-38 recapping Query

 

Bruce,
Thanks for additional info. ?I will verify I only have DC there.
?
?
Re: S-38 recapping Query

 

Crap! ?12SK7¡­.?

On Tue, Jan 21, 2025 at 11:31?AM Bruce Collins via <kb0tj1=[email protected]> wrote:
The small capacitor on the screen node of the 12SK87 is to insure there is no AC ripple or any RF on the screen.?
There should only be DC here.?
Re: S-38 recapping Query

 

The small capacitor on the screen node of the 12SK87 is to insure there is no AC ripple or any RF on the screen.?
There should only be DC here.?
Re: S-38 recapping Query

 

Richard and Don,
Thank you for the info and help with my project. ??
?
73
Barry W4LSV
Re: SX-62 Part Needed

 

Thanks to everyone who replied to my plea.? I have secured the solution.
Re: Dow Relay for HT-44

 

Skip - I don't mess with the relays.? I use a Johnson T/R switch - all electronic switching - and it works perfectly.? The B&W T/R switch also works well in this application.
?
73, Floyd - K8AC
Re: SX-62 Part Needed

 
Edited

¿ªÔÆÌåÓý

Markus,

I have several different sizes?of the cord pulley. These are Hallicrafters spare parts. If you could send me the diameter, and the thickness I may be able to match it.


Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.


From: [email protected] <[email protected]> on behalf of Markus Thomerson K5UFO DRO3 <k5ufo@...>
Sent: Saturday, January 18, 2025 3:58 PM
To: [email protected] <[email protected]>
Subject: Re: [HallicraftersRadios] SX-62 Part Needed
?
Hello.
I am in need of a mechanical part for my SX-62B. The dial pointer travels on it and the whole unit moves side to side to allow for the dial pointer reset. Mine is pictured below and as you can see the pulley on the left is missing. I am looking to buy the complete unit. I will buy a junker if need be to avoid turning my current SX-62B into one.



Thanks for reading, Markus.
Re: SX-62 Part Needed

 
Edited

¿ªÔÆÌåÓý

Markus,
I don't have an extra SX-62, but I do have a metal lathe and could turn the pulley and its shaft without much trouble.? If you don't get any bites for the whole assembly, let me know!
Mike

From: [email protected] <[email protected]> on behalf of Markus Thomerson K5UFO DRO3 <k5ufo@...>
Sent: Saturday, January 18, 2025 4:58 PM
To: [email protected] <[email protected]>
Subject: Re: [HallicraftersRadios] SX-62 Part Needed
?
Hello.
I am in need of a mechanical part for my SX-62B. The dial pointer travels on it and the whole unit moves side to side to allow for the dial pointer reset. Mine is pictured below and as you can see the pulley on the left is missing. I am looking to buy the complete unit. I will buy a junker if need be to avoid turning my current SX-62B into one.



Thanks for reading, Markus.
Re: SX-62 Part Needed

 
Edited

¿ªÔÆÌåÓý

Hello.
I am in need of a mechanical part for my SX-62B. The dial pointer travels on it and the whole unit moves side to side to allow for the dial pointer reset. Mine is pictured below and as you can see the pulley on the left is missing. I am looking to buy the complete unit. I will buy a junker if need be to avoid turning my current SX-62B into one.



Thanks for reading, Markus.
Re: Ballast Resistors? Source?

 

I take the point about the wattage. I will go to a 10W resistor in the appropriate resistance.?
Re: Ballast Resistors? Source?

 

¿ªÔÆÌåÓý

If Jim is right about R-68 {I have not looked at the circuit}? we should be worried about R68 wattage.? As Jim says.

A related thing;? when these were produced, what was the rated temperature rise and rated ambient temp used in the standards? And what is it now?? In general it seems that replacement resistors are now smaller in surface area, so they must run much hotter ?than originals, which also means that they will tend to over-heat neighboring components if allow to run hot .

I am no expert on this, but if anyone has real data on these standards I would like to see it. ?Of course there might be various standards too. ?


--
don??? va3drl
Re: Ballast Resistors? Source?

 

Richard, thanks for getting me untangled. I am studying for tech, I was a novice back in 1980, so relearning things. I asked about the 300 Ohm pair in series because I can find 300 Ohm? Axial Ceramic Cement Power Resistor 5W easily but not 600 Ohm. ?Thanks for clearing up the 5 per cent vs 10 per cent tolerances. ?
Re: Ballast Resistors? Source?

 

Jim, thanks for setting me straight. I realize I would need to wire two 300 Ohm in series to get 600 Ohms. I can find 300 Ohm 5W 10 percent? Axial Ceramic Cement Power Resistors easily enough but have not found a 600 Ohm listed yet. I will replace the big silver can capacitor as I suspect that is where the failure occured.?
Re: Ballast Resistors? Source?

 

In SERIES, parallel will give you half the value. Maybe this was a
typo.
Generally speaking the closer the tolerance the better, i.e. 5% is
better than 10% but the actual value is what is important. Resistors
and capacitors are often closer to their nominal value than the
tolerance limits. Using resistors or capacitors in either series or
parallel will tend to average out their values, i.e. improve their
accuracy. But, not always, a bunch from the same lot may all be high or
low and using them in series or parallel won't improve the overall
accuracy.
For many applications in old radios the original resistors were
only about 20% accuracy, more modern units are almost always 10% or better.
If you are replacing low power carbon composition resistors use
modern carbon or metal film ones, they are much better and will last
forever. Modern plastic film caps are much better than the original
paper caps and both are probably cheaper.


On 1/18/2025 12:07 PM, Richard Oscoda via groups.io wrote:
Thanks for the supply lead. The soldering is messy because I was
removing a huge yellow capacitor that is not on the schmatic.
Showing my ignorance; can I create a 600ohm Axial Ceramic Cement Power
by using two 300 Ohm in parallel? ?Also, the 10 percrent figure is more
desireable than 5 percent?

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
Re: Ballast Resistors? Source?

 

This is not a precision circuit so the extra money spent for a 5% part means little, 10% is good enough.

I think that you mean to parallel two 600 ohm 5 watt resistors to make up a 300 ohm 10 watt resistor?? That is OK as long as you have enough room in that area.? I would place the two resistors side by side, not stacked.? If you plan to leave the original filter capacitor can in place, find a new location for the three replacement filter caps so that they do not block the radiated heat from the power resistors.? Heat is always the enemy of reliability.
Regards.
Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy


On Saturday, January 18, 2025 at 02:07:10 PM CST, Richard Oscoda via groups.io <upmeharties51@...> wrote:


Thanks for the supply lead. The soldering is messy because I was removing a huge yellow capacitor that is not on the schmatic.
?
Showing my ignorance; can I create a 600ohm Axial Ceramic Cement Power by using two 300 Ohm in parallel? ?Also, the 10 percrent figure is more desireable than 5 percent?
Re: Ballast Resistors? Source?

 
Edited

Checking the math and calculating resistor power ratings using the voltages found in the manual:
Power (R43) = (265v - 150v)^2 / 6000 ohms = 2.2 watts, which at 5w is a X2 safety margin.? OK
Power (R-69) = (265v - 205v)^2 / 1500 ohms = 2.5 watts, which at 5w is a X2 safety margin.? OK
Power R-68) = (305v - 265v)^2 / 300 ohms = 5.3 watts, which is not good design work when using a 5w part.??
It seems that R69 should be at least a 10 watt part so that it too has a X2 safety margin!

It also looks like the dreaded previous owner left C99 A, B & C in the circuit and poorly tacked soldered the replacement for C99B in parallel with the original filter capacitor.? To add to the problem, the location of the new replacement filter capacitor blocks the radiated heat form the three 5 watt power resistors.? So there is no wonder why R68 and perhaps R69 failed.? I assume that the only remaining good 5 watt resistor is R43 and it still measures close to 6k ohms?
Regards,
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy


On Saturday, January 18, 2025 at 12:52:22 PM CST, Dave Jordan via groups.io <wa3gin@...> wrote:


Amazon, eBay, Mouser


On Sat, Jan 18, 2025 at 1:28?PM Richard Oscoda via <upmeharties51=[email protected]> wrote:
Hello all, I am rebuilding a Hallicrafters SX-122.? Two of the three ballast resisters are broken.? Where do I find replacemets?
?
Re: Ballast Resistors? Source?

 

Thanks for the supply lead. The soldering is messy because I was removing a huge yellow capacitor that is not on the schmatic.
?
Showing my ignorance; can I create a 600ohm Axial Ceramic Cement Power by using two 300 Ohm in parallel? ?Also, the 10 percrent figure is more desireable than 5 percent?
Re: Ballast Resistors? Source?

 
Edited

¿ªÔÆÌåÓý

I buy most of my resistors and caps from Dave at

?

Less expensive then Digikey and Mouser.

?

Take some time and tidy up that soldering as well¡­¡­¡­.

?

Tom

W3TA

From: [email protected] <[email protected]> On Behalf Of Richard Oscoda via groups.io
Sent: Saturday, January 18, 2025 1:28 PM
To: [email protected]
Subject: [HallicraftersRadios] Ballast Resistors? Source?

?

Hello all, I am rebuilding a Hallicrafters SX-122. ?Two of the three ballast resisters are broken. ?Where do I find replacemets?

?
Re: Ballast Resistors? Source?

 
Edited

Amazon, eBay, Mouser


On Sat, Jan 18, 2025 at 1:28?PM Richard Oscoda via <upmeharties51=[email protected]> wrote:
Hello all, I am rebuilding a Hallicrafters SX-122.? Two of the three ballast resisters are broken.? Where do I find replacemets?
?
Ballast Resistors? Source?

 
Edited

Hello all, I am rebuilding a Hallicrafters SX-122. ?Two of the three ballast resisters are broken. ?Where do I find replacemets?
?
641 - 660 of 31976