Topics

uBITX woes, feeling disheartened. #ubitx

Nick VK4PP
 

excellent thanks to all, i put the relay in upside down and the feed back issue is gone, as well as im now getting watts out!

now to sort out the proper replacement or do a hack... hmmm...

73 everyone.
VK4PLN

K5ESS
 

The Panasonic DS2Y-S-DC12V looks to be compatible and doesn’t have a polarized coil.  Available from Mouser for $3.14.

https://www.mouser.com/productdetail/panasonic-industrial-devices/ds2y-s-dc12v?qs=sGAEpiMZZMs3UE%252bXNiFaVCLW1ZA8WQBLokc2Dgfcyjc%3D

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of nickpullen@...
Sent: Saturday, January 6, 2018 10:59 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBITX woes, feeling disheartened.

 

The relay is polarized opposite to the ubitx's requirements, looks like the VRS2H arnt polarized, so no issues there, I tacked a spare DS2E onto the bottom of K1's coils in reverse and it works.... so i just have to install the DS2E on he bottom of the board... lol...

 

Any chance that the replacement relay is polarised. With these relays with wrong polarity it wont latch!
See if there is a + or - sign next to coil drawing on top or bottom on your spare.

At 07/01/2018, you wrote:
Ok Gordon, you are a champion for all your help! Many thanks.

So I hooked up the watt meter and zero output, needle doesn't even flinch... So K3 is not switching. Which is what I'm getting testing continuity with DVM too.

So there is definitely 13.68v across pin 8 and 9 on K3 during TX . I do have another spare relay....

73.

 

It is a DS2 - 2 means latching type I think and has 2 coils as per Panasonic datasheet for this type number!


At 07/01/2018, you wrote:
New relay, but wrong relay it appears...
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Mike Bowthorpe
 

If the Panasonic relay you mention is the correct part number then you can get them from ebay.

https://www.ebay.co.uk/itm/1pcs-ORIGINAL-12VDC-DS2Y-S-DC12V-DS2Y-S-12V-AGY2323-Panasonic-Relay-8pins/272477012696?hash=item3f70e542d8:g:XeoAAOSwtpZYR4SJ

Mike B
G0CVZ 

David Beal
 

Hi all, 

I'm going to jump in here as it appears that I may have a similar issue.  
Symptom: Receive works fine, transmit has zero output power

I did adjust the radio bias: 
On 40m, As received, the bias pots were set for 500 mA on PTT-on with no audio input (should be about 700 mA).
Turning the pots fully clockwise gave a starting point of 380 m
A (should be 470 - 500 mA).
I adjusted each equally up to 700 mA adding +155mA from each pot (visually, the pots are set to within about 5 degrees of rotation) . 


Now, when I press PTT without any audio input, the radio consumes 700mA
When I press PTT and talk into the microphone: 

1. The current goes up on peaks to around 2 amps
2. In my headphones, I can hear my own voice. 
3. Using a receiver that I've placed next to the uBITX, I can hear my SSB transmission
4. Conclude that the PA is working but the RF isn't making it to the antenna.  
5. Switched to 29 MHz as this involves only two relays: KT1 and K3 and still no joy. 
6. Retouched up the solder on T11 "just in case" - no joy

7. Confirmed the relays are getting the expected control signals, reading voltage across each diode when I select the band and then press PTT. 



LPF 21-30 @ 29 MHZ : 
D11: 0v
D12: 0v
D13: 0v
D8: 12v

LPF 14-21 @ 14.5 MHZ : 
D11: 12v
D12: 0v
D13: 0v
D8: 12v

LPF 7-10 @ 7.3 MHZ : 
D11: 12v
D12: 12v
D13: 0v
D8: 12v

LPF 3.5-5 @ 3.9 MHZ : 
D11: 12v
D12: 12v
D13: 12v
D8: 12v

Question #1: Since D11 is not turned on for 29MHz, I'm concluding that I can probably eliminate KT1 and focus on K3 (the diode D8 is oriented the same way as for the other relays) - does this thinking pass a sanity check?

I'm also wondering - of all the relays on the board, why are we potentially seeing multiple K3 failures when the drive circuit is the same??  

Thanks Nick, Raj, Mike for all of the early work on this.  





--
Dave Beal
AE6RQ

 

Dave,

Do a check on he continuity between the antenna JACK center to K3 pin 14.

I have seen antenna connector like p2 not making contect.

If you hear your own voice in the headphone then K3 has a problem. This is highly likely... check
M1 and M2 are not disconnecting.

There are reports here that the supplied BNC needs to have a fatter center pin on the BNC male.
Maybe thats not making contact. In this case the RX will not work.

Raj


At 14/01/2018, you wrote:
Hi all,

I'm going to jump in here as it appears that I may have a similar issue. 
Symptom: Receive works fine, transmit has zero output power

I did adjust the radio bias:
On 40m, As received, the bias pots were set for 500 mA on PTT-on with no audio input (should be about 700 mA).
Turning the pots fully clockwise gave a starting point of 380 mA (should be 470 - 500 mA).
I adjusted each equally up to 700 mA adding +155mA from each pot (visually, the pots are set to within about 5 degrees of rotation) . 


Now, when I press PTT without any audio input, the radio consumes 700mA
When I press PTT and talk into the microphone:
1. The current goes up on peaks to around 2 amps
2. In my headphones, I can hear my own voice.
3. Using a receiver that I've placed next to the uBITX, I can hear my SSB transmission
4. Conclude that the PA is working but the RF isn't making it to the antenna. 
5. Switched to 29 MHz as this involves only two relays: KT1 and K3 and still no joy.
6. Retouched up the solder on T11 "just in case" - no joy

7. Confirmed the relays are getting the expected control signals, reading voltage across each diode when I select the band and then press PTT.


LPF 21-30 @ 29 MHZ :
D11: 0v
D12: 0v
D13: 0v
D8: 12v

LPF 14-21 @ 14.5 MHZ :
D11: 12v
D12: 0v
D13: 0v
D8: 12v

LPF 7-10 @ 7.3 MHZ :
D11: 12v
D12: 12v
D13: 0v
D8: 12v

LPF 3.5-5 @ 3.9 MHZ :
D11: 12v
D12: 12v
D13: 12v
D8: 12v

Question #1: Since D11 is not turned on for 29MHz, I'm concluding that I can probably eliminate KT1 and focus on K3 (the diode D8 is oriented the same way as for the other relays) - does this thinking pass a sanity check?

I'm also wondering - of all the relays on the board, why are we potentially seeing multiple K3 failures when the drive circuit is the same?? 

Thanks Nick, Raj, Mike for all of the early work on this. 

[]



--
Dave Beal
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David Beal
 

Thanks Raj - 
Receive seems to work fine - but will check your suggestions tomorrow. 

I'm confused about M1, M2. I'm reading the schematic to indicate that both go to ground, so the relay is switching ground to ground??  
--
Dave Beal
AE6RQ

 

No Dave,

M1 and M2 are seen at the volume control and relay K2 in the schematic.
Signal from audio preamp is disconnected from output amp U1 so that your microphone doesnt leak through R114 and get amplified
by U1 amp. So if you hear your own voice in the speaker or phones then K2 is faulty!

Relay defects have been reported and should be checked.

Raj

At 14/01/2018, you wrote:

I'm confused about M1, M2. I'm reading the schematic to indicate that both go to ground, so the relay is switching ground to ground??
--
Dave Beal
AE6RQ

David Beal
 

Hi Raj, 

OK - I found the connection to M1 and M2; thanks (my oops reading the square M1-M4 boxes at the top; I guess I should have applied )  
Yes, I can hear my own voice in the phones; so - I'm waiting for that Panasonic relay to arrive.  In the meantime, I'll add the SCAF and play with the receiver.  

Thank you for your patience and assistance here Raj. 

--
Dave Beal
AE6RQ

 

Welcome Dave,

before you replace the relay please verify the continuity between M1 and M2 during RX and TX.

Rx = shorted
Tx = open

Raj

At 14/01/2018, you wrote:
Hi Raj,

OK - I found the connection to M1 and M2; thanks (my oops reading the square M1-M4 boxes at the top; I guess I should have applied )
Yes, I can hear my own voice in the phones; so - I'm waiting for that Panasonic relay to arrive. In the meantime, I'll add the SCAF and play with the receiver.

Thank you for your patience and assistance here Raj.
|

David Beal
 

Hi Raj, 
Measuring across the volume pot: 

orange to green:  730 ohms
green to yellow: 9.2k
yellow to orange: 8.6k

All measurements remain the same for PPT ON/OFF
The ohm meter (digital) does "flicker" on press or release of the PTT switch but settles back to the same reading no matter if its PPT ON or OFF. 

--
Dave Beal
AE6RQ

 

Dave,

NOT the volume control!

Please measure continuity across points M1 and M2 during RX - it should be shorted and press PTT and again check - it should be open.
Please trace the circuit..

Raj

Nick VK4PP
 

HI Dave, see the pics below, this is where you measure between these points for continuity during RX and no connection during TX:





73, Nick, VK4PLN

David Beal
 

Thank you so much Nick and Raj - 

Apparently, my brain went on for lunch and forgot to tell my body. 

I measure 0.3 ohms PTT ON and also OFF. 

A new relay should be here in a week or so. 
 

--
Dave Beal
AE6RQ

Nick VK4PP
 

2 Tips for you with replacing the relay.;

1: Check the new relay isnt polaraized before you install it.... see my experience...
2: A method i use to remove solder is to connect up a 8mm tube to the vacume cleaner via an adapter, and heat up the solder pad, then quickly suck the liquid solder away from each hole, works rather well...

Jim Sheldon
 

Wow Nick, I had never thought of using a vacuum cleaner to suck off the solder!  There should be plenty of suction there for that and you could use some of that silicone tubing they use at the end of those spring loaded solder suckers to keep it from getting melted by the Iron.  The vacuum cleaner idea would also work quite well for getting surface mount components off a board using one of those hot air rework stations for the heat.

Thanks for a super idea and I'll have to build up something for my Shop Vac to do just this!

Jim Sheldon - W0EB

------ Original Message ------
Sent: 1/15/2018 8:31:02 PM
Subject: Re: [BITX20] uBITX woes, feeling disheartened.

2 Tips for you with replacing the relay.;

1: Check the new relay isnt polaraized before you install it.... see my experience...
2: A method i use to remove solder is to connect up a 8mm tube to the vacume cleaner via an adapter, and heat up the solder pad, then quickly suck the liquid solder away from each hole, works rather well...

Chris Herd
 

Hi All

I have a suggestion, note I dont have a uBITX yet, I have one ordered so I cannot test this.

 If you disconnect the PA power at the DC input socket the transmitter wont produce RF.

The path from the antenna to the PA output transformer is DC when the PTT is activated, note the PA transformer end it at earth.

Use a multimeter set to ohms and measure the resistance between ground on the radio board and the antenna output while activating the PTT, it should be very low.

You also need to check the bands that activate the other LOW pass filters.

Hopefully this can help steer the thinking in others.

Best regards

Chris
ZL2TCH 

David Beal
 

Hi Jim, 
Thanks for the vacuum cleaner idea.

Instead of a piece of plastic hose, I borrowed one of my wife's wire/cardboard coat hangars like this:  http://static1.1.sqspcdn.com/static/f/549887/6555253/1271357721680/Coat+Hangers+02-Web.jpg  

using the thick cardboard tube as my sucker.  It worked very well and didn't burn. 
--
Dave Beal
AE6RQ

David Beal
 

Good evening, 

After I removed K3, I found that it had an open on the coil, but still with the new K3 still no joy. 

I'll follow Chris Herd's suggestion below as well as review the other threads here on a quest for hints. 

Thank you for your help. 

--
Dave Beal
AE6RQ