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Re: Ft-301ad blinking s-meter no transmit

 

I recall having this problem many years ago, kind of fuzzy, but as I recall I simply replaced the triac and all was good again.? That would be easy to try.? Good luck.? It is very nice to see this group helping one another.? ?73
Re: Ft-301ad blinking s-meter no transmit

 

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Steve,

My deep experience is only in the following FT-301D areas so I have no no input for you.

1. 100 watt booster
2. Elcon EL-31 display mod
3. Elcon EL-33 VFO mod
4. IF and Filter board.

The LPF board is a signal purity for FCC compliance, period.
The unfiltered RF has many 2rd, 3rd order harmonics.
The LPF whacks them down.

My blanking and 10 watt amps have always been functional so I haven't had to understand them, sorry.

Best wishes,

Randy

On 5/6/2020 7:38 PM, KI7WQH Steve wrote:

Yes, there is no continuity between K1 and K2 when the power is on.

I think I'm misunderstanding something. From what I can see on the block diagram, the LPF unit is like a gateway between the PA and then antenna. The relay on the LPF unit needs to be closed in order to transmit. For some reason on this radio the relay is open, which is the root of the problem. I thought by bypassing the relay and just jumping K1 to K2 it would essentially take the LPF unit out of the mix and the radio would transmit. This doesn't seem to be the case. So I think I'm misunderstanding what the LPF and blanking units do.
Re: Ft-301ad blinking s-meter no transmit

 

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The LPF unit is the transmitter low pass network but also contains the VSWR detector and the trip control for the Protector. If high SWR or a fault in the detector circuit itself, the Protector will activate. That relay is not a pass-through but must be closed in order for the transmitter section to work properly.?

Look at the wiper of the potentiometer that supplies drive to the thyristor gate. Is there any DC voltage present?

73 - Fred, N8YX?


-------- Original message --------
From: KI7WQH Steve <sdandrus@...>
Date: 5/6/20 10:38 PM (GMT-05:00)
To: Fred_N8YX <N8YX@...>, [email protected]
Subject: Re: [yaesuft301d] Ft-301ad blinking s-meter no transmit

Yes, there is no continuity between K1 and K2 when the power is on.

I think I'm misunderstanding something. From what I can see on the block diagram, the LPF unit is like a gateway between the PA and then antenna. The relay on the LPF unit needs to be closed in order to transmit. For some reason on this radio the relay is open, which is the root of the problem. I thought by bypassing the relay and just jumping K1 to K2 it would essentially take the LPF unit out of the mix and the radio would transmit. This doesn't seem to be the case. So I think I'm misunderstanding what the LPF and blanking units do.
Re: Ft-301ad blinking s-meter no transmit

 

Yes, there is no continuity between K1 and K2 when the power is on.

I think I'm misunderstanding something. From what I can see on the block diagram, the LPF unit is like a gateway between the PA and then antenna. The relay on the LPF unit needs to be closed in order to transmit. For some reason on this radio the relay is open, which is the root of the problem. I thought by bypassing the relay and just jumping K1 to K2 it would essentially take the LPF unit out of the mix and the radio would transmit. This doesn't seem to be the case. So I think I'm misunderstanding what the LPF and blanking units do.
Re: Ft-301ad blinking s-meter no transmit

 

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Can you put an ohmmeter across K1 and K2 then check the resistance with power applied?



-------- Original message --------
From: KI7WQH Steve <sdandrus@...>
Date: 5/6/20 3:03 PM (GMT-05:00)
To: KI7WQH Steve <sdandrus@...>, [email protected]
Subject: Re: [yaesuft301d] Ft-301ad blinking s-meter no transmit

I just tried something that I think might change where the fault might be. Maybe I'm wrong about this, but the reed relay is connecting K1 and K2 if I understand things. I decided to risk it and to just jumper k1 and k2 power it on to see if that would hijack the protection circuit (albeit in a potentially harmful way) and get rid of the blinking S-meter light problem. As it turns out, the radio behaves exactly the same way with K1 and K2 jumpered together, bypassing the relay entirely. I'm not the best at reading schematics so I'm not sure if there might be more to it than that, but at the very least this rules out the relay.

Is there something I'm missing, or does this indicate that maybe the problem is with the blanking unite itself and not with pb1445?

Re: Ft-301ad blinking s-meter no transmit

 

I just tried something that I think might change where the fault might be. Maybe I'm wrong about this, but the reed relay is connecting K1 and K2 if I understand things. I decided to risk it and to just jumper k1 and k2 power it on to see if that would hijack the protection circuit (albeit in a potentially harmful way) and get rid of the blinking S-meter light problem. As it turns out, the radio behaves exactly the same way with K1 and K2 jumpered together, bypassing the relay entirely. I'm not the best at reading schematics so I'm not sure if there might be more to it than that, but at the very least this rules out the relay.

Is there something I'm missing, or does this indicate that maybe the problem is with the blanking unite itself and not with pb1445?
Re: Ft-301ad blinking s-meter no transmit

 

Is there something that would cause the protection circuit to trigger as part of a normal behavior (working as intended) even though it’s not transmitting, or is it designed to only trigger in transmit mode? I read somewhere in the manual that the rig would have to be powered down to reset the protection circuit if it was triggered. I’m assuming that means there is something that resets after the power is taken out of the circuit (something that maybe isn’t resetting?) Could that be the problem??

If the the next step is to test Q1301 and D1301, then that’s what I have to do. I would just like to avoid having to desolder these old components if I can. I’m not sure that I have the capability to properly test them even if I get them out without damaging them. Let me know if there are other things you think I ought to test first, otherwise wish me luck and I’ll dive in and give it a shot.
Re: Ft-301ad blinking s-meter no transmit

 

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I think you should be seeing full coil voltage there if the Protection circuit is in proper shape (hasn't triggered). The 1k ohm to ground reading with power off is a good sign - the relay coil has continuity.?

Next, check Q1301 or D1301. I'm betting the trouble lies with one of those two components.?

73 - Fred, N8YX?


-------- Original message --------
From: KI7WQH Steve <sdandrus@...>
Date: 5/5/20 8:14 PM (GMT-05:00)
To: KI7WQH Steve <sdandrus@...>, [email protected]
Subject: Re: [yaesuft301d] Ft-301ad blinking s-meter no transmit

Looks like Fred's response didnt show up for some reason but it went to my email so i'll post it here:

"Look at the emitter of Q1301 - top of the relay coil. See any voltage there when the rig is powered up?
?
Also check continuity of the relay coil from that point to ground with the power off.
?
73 - Fred, N8YX "

So I put the positive probe on pin 1 (i'm pretty sure this is pin 1 based on diagrams on the internet) of Q1301 and the negative to the negative of the power supply and while it was powered on I had about .38 volts detected. When powered off, there was about 1k ohms going back to the negative. It was tricky to get the probe in there without shorting stuff out but I'm pretty sure I got it right.
Re: Ft-301ad blinking s-meter no transmit

 

Looks like Fred's response didnt show up for some reason but it went to my email so i'll post it here:

"Look at the emitter of Q1301 - top of the relay coil. See any voltage there when the rig is powered up?
?
Also check continuity of the relay coil from that point to ground with the power off.
?
73 - Fred, N8YX "

So I put the positive probe on pin 1 (i'm pretty sure this is pin 1 based on diagrams on the internet) of Q1301 and the negative to the negative of the power supply and while it was powered on I had about .38 volts detected. When powered off, there was about 1k ohms going back to the negative. It was tricky to get the probe in there without shorting stuff out but I'm pretty sure I got it right.
Re: Ft-301ad blinking s-meter no transmit

 

Thanks for the info, just did as you suggested and it looks like the relay is wide open, no continuity. But does that mean the relay is bad or that it's not being told to activate? Is there a way to apply voltage directly to the relay to test if it is functioning or should I go straight to testing the D1301? Not to get ahead of myself but I'm not sure how I would go about testing the thyristor. I have a cheap chinese "transistor tester" that sometimes can't figure out older components but sometimes autodetects and correctly identifies resisters, caps, diodes, transistors, etc so I could try to use that. I also have a voltmeter/ohmmeter and a cheap chinese oscilloscope that I built from a kit but havent really used yet. I've been doing simple repairs to electronics for many years but I'm just now starting to learn about things more complex than just replacing obviously blown caps and broken wires etc.
Re: Ft-301ad blinking s-meter no transmit

 

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Disconnect the K1 and K2 terminals from everything else. Put an ohmmeter across those terminals and carefully isolate the LPF Board from everything else in the radio (use a piece of cardboard as a spacer/insulator). Power up the rig and watch the ohmmeter. It should read 0 ohms or close to it if the relay is pulling in properly.?

Let us know what you find.?

73 - Fred, N8YX?


-------- Original message --------
From: KI7WQH Steve <sdandrus@...>
Date: 5/5/20 10:03 AM (GMT-05:00)
To: sdandrus@..., [email protected]
Subject: Re: [yaesuft301d] Ft-301ad blinking s-meter no transmit

OK, it was actually easier than I thought. Now that I have access to the rear of this board, is there an easy way to test the relay? I feel like testing the relay will be way easier than testing the thyristor?with my knowledge level and equipment, but I'm here to learn.

Re: Ft-301ad blinking s-meter no transmit

 

OK, it was actually easier than I thought. Now that I have access to the rear of this board, is there an easy way to test the relay? I feel like testing the relay will be way easier than testing the thyristor?with my knowledge level and equipment, but I'm here to learn.
Re: Ft-301ad blinking s-meter no transmit

 

That's what I was afraid of. This is the one board they don't give you easy access to. I don't suppose there is a trick to accessing the back of this...
Re: Ft-301ad blinking s-meter no transmit

 

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Look at D1301 - a thyristor on the LPF Board. If this has failed shorted it'll cause the Protector circuit to open the associated relay and cause the Blanker circuit to flash the red meter lamp. It'll also shut down the exciter and amplifier sections of the transmit signal path. Also examine the relay - does it open as soon as power is applied to the rig? If not, could be as simple as a faulty (dirty) relay. No current through it means the SN7400 on the RF Board won't receive voltage and will block the transmitter from operating. Ditto the Blanker circuit.?

73 - Fred, N8YX?

-------- Original message --------
From: sdandrus@...
Date: 5/4/20 9:25 PM (GMT-05:00)
To: Randy W7CPA <randybest@...>, [email protected]
Subject: Re: [yaesuft301d] Ft-301ad blinking s-meter no transmit

Thanks for the reply. The in and out are jumpered together so the signal is going out the antenna jack. Just in case though I tried what you suggested and connected the dummy load to the out BNC and have the same results. To clarify, the S meter is always blinking, from the time it is powered up. I do not have to try to transmit for it to be blinking, its always in this state. If I do try to transmit, there is a relay that switches over but the radio puts out zero watts. I'm thinking it might be a problem with PB-1445, the protection circuit relay or something like that but am hoping someone might know a trick that will help me avoid testing every component.

Re: Ft-301ad blinking s-meter no transmit

 

Thanks for the reply. The in and out are jumpered together so the signal is going out the antenna jack. Just in case though I tried what you suggested and connected the dummy load to the out BNC and have the same results. To clarify, the S meter is always blinking, from the time it is powered up. I do not have to try to transmit for it to be blinking, its always in this state. If I do try to transmit, there is a relay that switches over but the radio puts out zero watts. I'm thinking it might be a problem with PB-1445, the protection circuit relay or something like that but am hoping someone might know a trick that will help me avoid testing every component.
Re: Ft-301ad blinking s-meter no transmit

 

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You need to connect the back panel BNC, labeled OUT through a power meter to a dummy load.
This is the 10 watt amp out. OUT is 10 watt amp output.
IN is the 100 watt amp IN to the BPF.
If you get them backwards you will see what you describe.

On 5/4/2020 8:46 AM, sdandrus@... wrote:

hello everyone, I’m rescuing a ft-301ad from the scrap yard. The issue I’m currently wrestling with is that the protection circuit is always engaged, preventing transmission. I have the linear amp removed from the rear and the 2 BNC connectors jumpered and the radio connected to a dummy load. When the radio is powered on, the light is already blinking. I don’t see any obvious damage inside the rig and was hoping this might be something people have had trouble with before. The pb-1445 described in the manual available online appears to be slightly different than mine, but I did try adjusting the 2 adjustable pots on the board that are similar to those mentioned in the manual for adjusting the protection circuit. No change was observed.?

Anyway, hopefully someone can point me in the right direction!

KI7WQH

Ft-301ad blinking s-meter no transmit

 

hello everyone, I’m rescuing a ft-301ad from the scrap yard. The issue I’m currently wrestling with is that the protection circuit is always engaged, preventing transmission. I have the linear amp removed from the rear and the 2 BNC connectors jumpered and the radio connected to a dummy load. When the radio is powered on, the light is already blinking. I don’t see any obvious damage inside the rig and was hoping this might be something people have had trouble with before. The pb-1445 described in the manual available online appears to be slightly different than mine, but I did try adjusting the 2 adjustable pots on the board that are similar to those mentioned in the manual for adjusting the protection circuit. No change was observed.?

Anyway, hopefully someone can point me in the right direction!

KI7WQH
Re: Welcome Friends

 

Hi Oz -
Congratulations on the FT301 analog rig!? It will be fun to follow along with your restoration of the radio.? This is a very nice radio with one of the very best receivers I have ever used.? Good deal on the shipping of the radio, that sure worked out well.? I am sure you will have the rig running 100% in the not so distant future.? Welcome aboard to the group!? Please keep in touch.
73 Rex K0KP
Re: Welcome Friends

 

Greetings from Vk5LTD in South Australia. ?I have a FT301 ( analogue tuning). with matching power supply. ? The radio does need a proper going through but is operational. ? Power is well down - it is the 100w version. ?I'll be sure to check in with the group when I make a start on the 301. ? This model was on the cover of an early radio theory book an I admired it every time. ? I came across the radio with a batch of CBs on market place. It was in another town, too far away to easily drive and test - 10 hour round trip. ? I had some clips of it powered on but no other tests so I took a punt on it and offer was accepted. ?They dropped it at a business I had dealings with and some weeks later they were coming to town so dropped it in at the cost of a nice chilled white wine. ?

I also have a FT-901D and FT101E from the Yaesu stable. ?
73 from Oz
Re: FP-301D ID PROM

 

JAMECO has these perfect matches.
I will report programming progress.
The 288s are just more robust for MIL applications.
The CW ID should be a no brainier.

https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=-1&storeId=10001&productId=48717
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