Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Sep Mon 24, 2018 8:04 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 16 posts ] 
Author Message
 Post subject: HQ-120-X
PostPosted: Feb Wed 11, 2015 4:14 am 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Greetings all

I'm sure some of you were following my SX-28A saga. After getting more frustrated I decided to box it up and save it for another day. When your hobby stops being fun, and starts to be more frustrating, it's time for a change. It'll be there when I'm ready to tackle it.

So, what to do next. I have an HQ-129-X that I've used on and off for years. Looks great and is in fine shape. I also have an HQ-120-X that I've never fired up, but it was given to me by my Elmer (I doubt he was the owner.....) so I have a sentimental attachment to it. I decided to start looking into the HQ-120-X.

The underside is what I'd call well aged components. Aside from the PS section, all the parts look original. I've spent a few evenings mapping out the parts and testing them, and so far I haven't found a single resistor in spec. All the capacitors are well used wax paper types. While some of the parts look roasted, I haven't found any that have been burned etc. No popped resistors (although I did see a cracked one.....); they all ohm out, albeit kinda high......

What concerns me is the power supply section. The 3 stage filter cap had one stage replaced by a standalone capacitor. No big deal there.

The power transformer and the audio transformer have both been replaced.

Obviously I wasn't going to fire up the radio in the state is was in, but I did want to try the power transformer. So, I removed the 5U4GB rectivier and brought the transformer up on a variac. It hits about 550V AC at 117 in. That's OK, until I started looking at the schematics. Using the voltage chart, I figure I should be seeing about 275V after the first choke (#18) and about 220V after the second choke (#20). I really have a hard time believing the first choke is going to be expected to drop about 275V AC! I also figure the higher voltage is why the original owner replaced the 5V4 with the 5U4. Do any of you know the specs on the HQ-120-X power transformer?

The audio transformer is a Chicago A-3823 tranny; 4K Primary, 14K secondary. Again, I have no idea what the specs were on the original to know if this replacement is OK.

The main tuning dial is badly warped and the lamenations are coming apart. I can still tune with it, but I'd like to find a replacement and I think the one from an HQ-129-X or HQ-140 will work.

I've been mapping the schematic to the parts layout in the IF area, and I should complete that this week. Then it's on to the PS section. I need to verify both chokes are OK and address the PS tranny issue before I decide to start work on it or wait until I can find suitable replacement parts.

Comments welcomed.

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Wed 11, 2015 4:57 am 
Member

Joined: Feb Tue 07, 2012 9:32 pm
Posts: 1789
Location: Middlesex,NJ
HI MARK.

IF YOU DO NOT HAVE THE RIDERS SCHEMATICS HERE IS THE LINK.VOLUME 10 AND 12.

http://www.nostalgiaair.org/Resources/181/T0000181.htm

WALTER-W2WIQ


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Wed 11, 2015 9:52 am 
Member
User avatar

Joined: Nov Mon 02, 2009 7:01 am
Posts: 2993
Location: Lincoln City, OR
Greetings to K3MSB and the Forum:

K3MSB writes:

Quote:
So, I removed the 5U4GB rectivier and brought the transformer up on a variac. It hits about 550V AC at 117 in. That's OK, until I started looking at the schematics. Using the voltage chart, I figure I should be seeing about 275V after the first choke (#18) and about 220V after the second choke (#20). I really have a hard time believing the first choke is going to be expected to drop about 275V AC!


I have to ask: Where are you measuring this voltage? If it is across the entire high voltage winding ( between pins 4 and 6 of the 5U4 socket ) then it is about right. The high voltage winding is center-tapped. Only 1/2 of the winding contributes to the voltage on the 5U4 filament at any one time. Effectively, each half of the high voltage winding together with one plate of the 5U4 constitutes a half-wave rectified voltage source. Since there are two halves of the winding and two 5U4 plates and the voltage at the ends of the winding are 180 degrees out of phase with each other, the end result is full-wave rectification at 1/2 the total voltage of the power transformer secondary.

If your measurement of 550 volts is across the entire secondary and is a true RMS reading, then the voltage expected at the input to the first choke will be 205 volts DC average (pulsating DC at this point) due to there being about 20 volts drop across the 5U4. The peak voltage at this point should be about 298 volts after the rectifier drop is considered. If the supply was capacitor input, you could expect the input cap to charge to somewhere near this voltage, depending on the size of the cap and the load current. However, as I recall, the Hammarlund power supplies of this vintage are choke input, so the voltages given in your data should be pretty close to correct.

Regards,
Jim T.
KB6GM

_________________
Jim T.
KB6GM


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Wed 11, 2015 2:28 pm 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Hi Jim

Ugh! I missed the center tap on the schematics! Thanks for pointing that out. The PS is a cap input supply.

Walt --

Thanks for the links. I had the Riders Vol 10, but not the one for the later version. I shall compare the two.

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Wed 11, 2015 2:32 pm 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Here's a few photos. I think this project will involve replacement of all the parts; I doubt any of the resistors will be in tolerance, and of course all the caps will be replaced.....


Attachments:
hq-1.jpg
hq-1.jpg [ 81.25 KiB | Viewed 3687 times ]
hq-2.jpg
hq-2.jpg [ 73.23 KiB | Viewed 3687 times ]
hq-3.jpg
hq-3.jpg [ 82.74 KiB | Viewed 3687 times ]

_________________
73 Mark K3MSB
www.k3msb.com
Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Wed 11, 2015 4:52 pm 
Member

Joined: Feb Tue 07, 2012 9:32 pm
Posts: 1789
Location: Middlesex,NJ
HI MARK:

HERE IS THE LINK TO BAMAS.

http://bama.edebris.com/manuals/hallicra/s120/

WHEN I REMOVE WIRES FROM AN ELECTROLYTIC BEFORE RESTUFFING I BIND ALL THE WIRE FROM 1 TERNINAL WITH THESE SMALL WHITE TAGS WITH A STRING AND MARK THE TAG WITH THE TERMINAL SYNBOL.THIS I DO WITH EACH TERMINAL.IN YOUR FIRST PICTURE I SAW SINGLE ELECTROLYTICS WITH A NUT.AFTER REMOVEING THE WIRES USE A SOCKET TO REMOVE THE NUT.

THE WIRES SEEM TO LOOK IN PRETTY GOOD CONDITION.TRY NOT TO DAMAGE THEM IN REPLACEING ALL THE CAPS AND RESISTORS.

GOOD LUCK.

WALTER-W2WIQ


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Wed 11, 2015 5:23 pm 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Hi Walter

I already have the manual from bama. Not the best, but you can't beat the price. I'm glad the resource is available!

I will not be restuffing the capacitors; they will be replaced. Since I know of no way to restuff resistors, the resistors will be modern. Since the resistors will be modern, I can't see the point of restuffing the wax paper caps. I do save all original parts when I do a radio; they are never discarded.

The exception will be the 3 stage electrolytic in the power supply; that I will probably restuff.

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Wed 11, 2015 8:19 pm 
Moderator
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22446
Location: Somers, CT
Good photos. Take photos of every area you are working in. If you get confused, the photos will help if question arises.

Pete

_________________
Just because it can be done doesn't mean it should be done.


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Fri 13, 2015 6:49 pm 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
I've been fortunate to get an hour or two of radio time in the past few nights and work is proceeding nicely.

I figure I have about 80% of the parts identified under the chassis, and have the area around the 5V4G left to do. A lot of the parts are so monolithic brown that even my wife, who is getting pretty good at reading color codes, can't decipher them.

I saw a bit of electrical tape peeking out from under one of the chokes, so I used an inspection mirror and found a bare (as in naked) connection between the choke body and metal chassis! While getting the choke out I found that the replacement transformer installation managed to squeeze a wire between it's bottom and the chassis....... Ugh. Those items will get fixed!


Attachments:
20150212_213557.jpg
20150212_213557.jpg [ 115.67 KiB | Viewed 3560 times ]
20150212_213700_LLS.jpg
20150212_213700_LLS.jpg [ 201.47 KiB | Viewed 3560 times ]

_________________
73 Mark K3MSB
www.k3msb.com
Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Sat 14, 2015 8:10 am 
Member

Joined: May Sun 13, 2007 5:22 am
Posts: 195
Location: United Kingdom
A friend, Paul Carlson, has produced a nice video of a restoration of a HQ120. It's a long one so grab some popcorn.

https://www.youtube.com/watch?v=J31nVC0ms0w


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Sat 14, 2015 3:17 pm 
Member
User avatar

Joined: May Fri 04, 2012 10:39 pm
Posts: 1409
Location: Hidden Valley, AZ
I have several 120 & 129 parts widows, so if you need good original items, pleas let me know.

Dennis

_________________
Workin' my Gramophone in a smartphone world.


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Sat 14, 2015 4:26 pm 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Wow! Over two hours! That will kill some of my lunch hours next week. Thanks Bruce!

Bruce MacMillan wrote:
A friend, Paul Carlson, has produced a nice video of a restoration of a HQ120. It's a long one so grab some popcorn.

https://www.youtube.com/watch?v=J31nVC0ms0w

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Sat 14, 2015 4:26 pm 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Definitely interested Dennis. PM Coming.....

W7TFO wrote:
I have several 120 & 129 parts widows, so if you need good original items, pleas let me know.

Dennis

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Feb Thu 19, 2015 3:13 am 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
I'm having some trouble reading the schematics for the HF Oscillator part of the circuit, specifically Bandswitch BS-1 wafer 56.

I understand how part of the switch is changing the variable coils and associated trimmer caps etc as they are the "inner ring" on the schematic wafer symbol. The outer ring is what puzzles me; I see that one common wire goes to R57 thence to ground, but where is the other common tap?

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Mar Thu 05, 2015 8:02 pm 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Greetings from snowy and icy central PA!

All the replacements resistors and caps arrived from Just Radios the other day, and stock power and audio transformers as well as a replacement dial are inbound thanks to Dennis W7TFO!

C19 In the power supply filter stage is a 3 stage capacitor: 16uF / 450V, 16uF 350V and 8uF 450V.

The colors on the C19 wires are so old and blackened that neither I nor my wife can read them and I'm not sure abut two of the stages.

I think the 16 uF 450V connection goes at the junction of L18 and L20. This is because there was a replacement capacitor for this section of the 3 stage capacitor installed in the radio.

I would expect the 8uF section to be at the end, but since it has a 450V rating perhaps it goes to the junction of the 5V4 and L18?

Thanks!

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
 Post subject: Re: HQ-120-X
PostPosted: Jun Tue 09, 2015 12:43 am 
Member

Joined: Aug Mon 09, 2010 2:57 am
Posts: 405
Location: York PA.
Greetings

I know someone sent me clarification on my capacitor question, but I can't find the response.

I think the answer is

8 uF 450V at input to L-18
16 uF 450 at junction of L-18 / L20
16 uF 350V at output of L-20

Can someone please confirm?

Thanks!

k3msb wrote:
Greetings from snowy and icy central PA!

All the replacements resistors and caps arrived from Just Radios the other day, and stock power and audio transformers as well as a replacement dial are inbound thanks to Dennis W7TFO!

C19 In the power supply filter stage is a 3 stage capacitor: 16uF / 450V, 16uF 350V and 8uF 450V.

The colors on the C19 wires are so old and blackened that neither I nor my wife can read them and I'm not sure abut two of the stages.

I think the 16 uF 450V connection goes at the junction of L18 and L20. This is because there was a replacement capacitor for this section of the 3 stage capacitor installed in the radio.

I would expect the 8uF section to be at the end, but since it has a 450V rating perhaps it goes to the junction of the 5V4 and L18?

Thanks!

_________________
73 Mark K3MSB
www.k3msb.com


Top
 Profile  
 
Post New Topic Post Reply  [ 16 posts ]  Moderator: Sandy

All times are UTC [ DST ]


Who is online

Users browsing this forum: n4crz, rsingl and 2 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB