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SR-400 parts and service availability

 

Directing this question to those of you who do your own or other ham's service work on the SR-400 and its power supply.? Have you often encountered needed components being unavailable or in such short supply that you were not able to do a repair?? I am seriously considering adding a SR-400 to the shack and I was concerned that I might not be able to find the necessary components on the market to keep the radio working properly.? Thanks, Tom KF5WBS
Re: HT-44 Mic audio problem

 

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I forgot to address R56. The schematic in the repair manual is of a first run unit. That was changed and your radio is correct.

It may be time for an update, I have several items on the change list.


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


From: [email protected] <[email protected]> on behalf of Floyd - K8AC <floydsense@...>
Sent: Thursday, March 21, 2024 12:44 PM
To: [email protected] <[email protected]>
Subject: [HallicraftersRadios] HT-44 Mic audio problem
?
Yesterday, the mic audio circuit was operating just fine and developed a new problem today.? In CW mode, the mic amp is disabled by applying bias to the grid of V2 (pin7) of the 12AX7 first and second audio amp.? That is happening as it should with -159V on the grid.? In AM and SSB modes, the bias is removed through contacts on the Function switch.? I'm getting no audio through the audio strip and find that the grid of the 12AX7 (pin 7) is at a -49V level.? Should be around -0.7V according to Walt's Repair Manual.? Haven't been able to figure out the source of that voltage yet.? I have found that the wiring of that grid circuit differs from the schematic in the Repair Manual and the one in the Operating and Service Instructions manual.? In my unit, R56 is wired between pin7 and R58 with R58 connected directly to C78.? Ideas?

73, Floyd - K8AC

Re: HT-44 Mic audio problem

 

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Be sure to change your circuit according to the diagram!!

As it is now, the grid is pulled up directly to the positive via R56,

clearly it doesn't work as it should

?

Best 73 (HB9HPZ)

Franz

?

Von: [email protected] <[email protected]> Im Auftrag von Floyd - K8AC
Gesendet: Donnerstag, 21. M?rz 2024 18:44
An: [email protected]
Betreff: [HallicraftersRadios] HT-44 Mic audio problem

?

Yesterday, the mic audio circuit was operating just fine and developed a new problem today.? In CW mode, the mic amp is disabled by applying bias to the grid of V2 (pin7) of the 12AX7 first and second audio amp.? That is happening as it should with -159V on the grid.? In AM and SSB modes, the bias is removed through contacts on the Function switch.? I'm getting no audio through the audio strip and find that the grid of the 12AX7 (pin 7) is at a -49V level.? Should be around -0.7V according to Walt's Repair Manual.? Haven't been able to figure out the source of that voltage yet.? I have found that the wiring of that grid circuit differs from the schematic in the Repair Manual and the one in the Operating and Service Instructions manual.? In my unit, R56 is wired between pin7 and R58 with R58 connected directly to C78.? Ideas?

73, Floyd - K8AC

Re: HT-44 VOX issue

 

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Sorry Floyd, for the confusion. The statement about the middle third of the control was meant to be a precautionary statement. That circuit is an extremely high impedance network. Any degradation of the circuit values will affect the circuit function.

Also, the mic gain needs to be set properly in MOX first.

On the voltage on pin 7 of V2. In standby around -40 volts is delivered to pin 7 via S3A FRONT pins 9 & 10. In all other positions of the operation switch that line is open and the tube develops grid leak bias in the amount of about -0.5 volt.


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


From: [email protected] <[email protected]> on behalf of Floyd - K8AC <floydsense@...>
Sent: Thursday, March 21, 2024 12:31 PM
To: [email protected] <[email protected]>
Subject: Re: [HallicraftersRadios] HT-44 VOX issue
?
I accept that is true, but, my question was about the VOX system when used with AM and SSB.? The gain control must be in the upper third or less for the VOX to trip at all.? Your book indicates that's a problem.? Unfortunately, my HT-44 has developed a problem in the mic amp circuit which precludes me from pursuing the VOX issue.? I will post that in another thread for less confusion.

73, Floyd - K8AC??

HT-44 Mic audio problem

 

Yesterday, the mic audio circuit was operating just fine and developed a new problem today.? In CW mode, the mic amp is disabled by applying bias to the grid of V2 (pin7) of the 12AX7 first and second audio amp.? That is happening as it should with -159V on the grid.? In AM and SSB modes, the bias is removed through contacts on the Function switch.? I'm getting no audio through the audio strip and find that the grid of the 12AX7 (pin 7) is at a -49V level.? Should be around -0.7V according to Walt's Repair Manual.? Haven't been able to figure out the source of that voltage yet.? I have found that the wiring of that grid circuit differs from the schematic in the Repair Manual and the one in the Operating and Service Instructions manual.? In my unit, R56 is wired between pin7 and R58 with R58 connected directly to C78.? Ideas?

73, Floyd - K8AC
Re: HT-44 VOX issue

 

I accept that is true, but, my question was about the VOX system when used with AM and SSB.? The gain control must be in the upper third or less for the VOX to trip at all.? Your book indicates that's a problem.? Unfortunately, my HT-44 has developed a problem in the mic amp circuit which precludes me from pursuing the VOX issue.? I will post that in another thread for less confusion.

73, Floyd - K8AC??
Re: SX-100 Repair Problems

 

Check the resistors while out too. I found 3 out of tolerance.


On Wed, Mar 20, 2024 at 6:10?PM Keith <kd4avp@...> wrote:
Thanks Donald! I was thinking that would be the smart thing to do....not simple but definitely the right way to access them.?
I am pretty good at making myself a road map as I go thru these radios.?
The SX100 is by far the most complicated one to come across my bench.
I have done a SX99 and have a SX96 up for rehab also.?
Just something about the look of the SX100 makes me want to tackle it next,.

Re: Bristol L-wrench kit, set of 9

 

Another source.
Re: SX-100 restore project

 

Keith,

Thanks for your insights.

CRC makes 4 products ( out of a portfolio of 147) that focus on Electronics:

1) QD? Electronic Cleaner ( which you used)

2) Electronic Component Cleaner

3) Lectra-Motive Electric Parts Cleaner

4) Auto Electronic Cleaner


73's

Pete

W8AA?


On Wed, Mar 20, 2024 at 10:22 PM, Keith
<kd4avp@...> wrote:
I also have seen good results from the WD40 version. Personally have not used it, but seen other results from that product that looked great. It is also a little cheaper.

Re: SX-100 restore project

 

I also have seen good results from the WD40 version. Personally have not used it, but seen other results from that product that looked great. It is also a little cheaper.
Re: SX-100 restore project

 

Let me add on the CRC if you have not used it. It will smell up a room. I took it outside my shop on a work surface and just turned loose on it. Left it to sit for about 10 mins then did the Q tip and brush routine.
Re: SX-100 restore project

 
Edited

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Pete

?

I used the CRC Quick Dry Electronic cleaner. I used a LOT out of a large can. I really laid into the chassis.

Dried very very quickly. Then followed up with large Q tips and brush.

?

Keith

?

?

From: [email protected] <[email protected]> On Behalf Of peteradio@... via groups.io
Sent: Wednesday, March 20, 2024 10:02 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-100 restore project

?

Keith,

?

Which CRC product did you use?

?

73's

?

Pete

?

W8AA?

?

On Wed, Mar 20, 2024 at 8:49 PM, Keith

<kd4avp@...> wrote:

Thank you so much John! Yes as I was reflecting on the bath idea, my dog assistant looked at me with that "You sure about this?" look. Had second thoughts as it probably would make more issues to fix rather than just leaving a crud behind. I can live with a little crud. I want a working radio. Thank you so much for your kind words! I will be leaning on the group as I go thru this project.?

73

Keith KD4AVP

Re: SX-100 restore project

 

Keith,

Which CRC product did you use?

73's

Pete

W8AA?


On Wed, Mar 20, 2024 at 8:49 PM, Keith
<kd4avp@...> wrote:
Thank you so much John! Yes as I was reflecting on the bath idea, my dog assistant looked at me with that "You sure about this?" look. Had second thoughts as it probably would make more issues to fix rather than just leaving a crud behind. I can live with a little crud. I want a working radio. Thank you so much for your kind words! I will be leaning on the group as I go thru this project.?

73

Keith KD4AVP

Re: SX-100 restore project

 

Thank you so much John! Yes as I was reflecting on the bath idea, my dog assistant looked at me with that "You sure about this?" look. Had second thoughts as it probably would make more issues to fix rather than just leaving a crud behind. I can live with a little crud. I want a working radio. Thank you so much for your kind words! I will be leaning on the group as I go thru this project.?

73

Keith KD4AVP
Re: HT-44 VOX issue

 

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The truncated first dit or dash is an annoying trait of the 44. Most people just get used to sending a dit to start a conversation.



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


From: [email protected] <[email protected]> on behalf of Floyd - K8AC <floydsense@...>
Sent: Wednesday, March 20, 2024 7:13 PM
To: [email protected] <[email protected]>
Subject: [HallicraftersRadios] HT-44 VOX issue
?
I'm in the home stretch of the HT-44 restoration, checking out the VOX circuit.? I suspected there might be a problem in the VOX because when testing on CW in the VOX position, the leading code element was being truncated severely.? This HT-44 does have the T/R relay installed, so the truncation may be the result of the pick time of that relay.? All new tubes have been installed.? On any of the phone modes, the VOX doesn't activate until the VOX gain control is in the upper third of the control rotation (anti-vox all the way CCW).? I'm using a dynamic mic and getting full power output with the mic gain set somewhere below 8.? The delay control works properly.

I've checked all the resistors in the diagram on page 24 of Walt's HT-44 repair manual except for R91, R95,R92, R87, R88 which I haven't tried to locate yet.? All the resistors were within 10-15% of the specified value.? No capacitors in the circuit were checked.? I'm wondering if what I'm seeing isn't close to normal, but Walt's book points out that the VOX control should be in the middle third of rotation when all is well.? Opinions on how to proceed?

73, Floyd - K8AC

HT-44 VOX issue

 

I'm in the home stretch of the HT-44 restoration, checking out the VOX circuit.? I suspected there might be a problem in the VOX because when testing on CW in the VOX position, the leading code element was being truncated severely.? This HT-44 does have the T/R relay installed, so the truncation may be the result of the pick time of that relay.? All new tubes have been installed.? On any of the phone modes, the VOX doesn't activate until the VOX gain control is in the upper third of the control rotation (anti-vox all the way CCW).? I'm using a dynamic mic and getting full power output with the mic gain set somewhere below 8.? The delay control works properly.

I've checked all the resistors in the diagram on page 24 of Walt's HT-44 repair manual except for R91, R95,R92, R87, R88 which I haven't tried to locate yet.? All the resistors were within 10-15% of the specified value.? No capacitors in the circuit were checked.? I'm wondering if what I'm seeing isn't close to normal, but Walt's book points out that the VOX control should be in the middle third of rotation when all is well.? Opinions on how to proceed?

73, Floyd - K8AC
Re: SX-100 Repair Problems

 

Thanks Donald! I was thinking that would be the smart thing to do....not simple but definitely the right way to access them.?
I am pretty good at making myself a road map as I go thru these radios.?
The SX100 is by far the most complicated one to come across my bench.
I have done a SX99 and have a SX96 up for rehab also.?
Just something about the look of the SX100 makes me want to tackle it next,.
Re: SX-100 Repair Problems

 

The easiest way to replace those is to remove the switch completely and then reattach the 4 or 5 wires back on the switch.
Take a picture first and tape/label the wires then remove them and then the rotary switch
I've done it twice with two rebuilt sx-100s

On Wed, Mar 20, 2024 at 1:25?PM Keith <kd4avp@...> wrote:
Thank you Jacques
I have heard of these dreaded black bugs.?
Plan to hit the red caps first. Those are the worst and doubt I get anywhere till those are replaced.
Not looking forward to replacing the black bees around one of the front panel controls. They are packed tight in there. Will have to remove the front face but that will have to happen anyway. They can be deceiving since they look so much like a fat resistor.?
Going slow!

Get
?
From: [email protected] <[email protected]> on behalf of Jacques_VE2JFE <jacques.f@...>
Sent: Wednesday, March 20, 2024 10:25 AM
To: [email protected] <[email protected]>
Subject: Re: [HallicraftersRadios] SX-100 Repair Problems
?

Exactly, YES !

?

73, Jacques, VE2JFE in Montreal

?

In the photo I have circled some components that I have a question about.
Pardon my lack of knowledge, but are these what are referred to as the "bumblebees"?

Re: SX-100 Repair Problems

 

Thank you Jacques
I have heard of these dreaded black bugs.?
Plan to hit the red caps first. Those are the worst and doubt I get anywhere till those are replaced.
Not looking forward to replacing the black bees around one of the front panel controls. They are packed tight in there. Will have to remove the front face but that will have to happen anyway. They can be deceiving since they look so much like a fat resistor.?
Going slow!

Get
?

From: [email protected] <[email protected]> on behalf of Jacques_VE2JFE <jacques.f@...>
Sent: Wednesday, March 20, 2024 10:25 AM
To: [email protected] <[email protected]>
Subject: Re: [HallicraftersRadios] SX-100 Repair Problems
?

Exactly, YES !

?

73, Jacques, VE2JFE in Montreal

?

In the photo I have circled some components that I have a question about.
Pardon my lack of knowledge, but are these what are referred to as the "bumblebees"?

Catching Up!

 

I hope all is well with you? I can't call for now, that's the reason why I emailed you. Actually, I need a favour from you. I'd appreciate if you could email me back when you get this ASAP.
?
Pete
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