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Author Topic: ARB-704 / Tuner Port REALLY a safe alternative?  (Read 5155 times)
KB1TJY
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Posts: 257




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« on: December 22, 2012, 03:41:35 PM »

I just purchased an ARB-704 for use with my Yaesu FT-450D. I also purchased a PNP Cable (PNP-8M) to connect the two. The FT-450D does not have any RCA jacks on the rear but does have a 8-Pin Tuner port and an 6-Pin DATA port.

The cable I was told to get is the PNP-8M. Normally this 8-pin cable would connect to the DATA port. However, the DATA port is only 6-Pin. What Ameritron did to work around this was as follows:

"ARB-704 Interface cable for Yaesu FT-817/840/857/890/897/450*/950* (If this is for use with the FT-450 or FT-950, it connects to the radio's "Tuner" port rather than the 10-pin "Linear" port. Yaesu charges a premium for the use of their 10-pin connector, so Ameritron chose to make a cable that works off of the tuner port! This lets you, the end user, accomplish the same results with a cable that's a third of the cost.)".

Ameritron has some good product but I've been to hell and back with them on some products and I want to make sure that connecting that to the Tuner Port isn't going to fry the radio. (Why they are referencing the 'Linear' port I do not understand, as (1) a cable is currently running from it to the Amp's Relay AND (2) it's 10 Pin and not 8-Pin).

The Amp is an Ameritron AL-80B.

Does anyone know if this will in fact work when connected to the Tuner Port? And does it interfere with the functionality of the Radio's built-in Tuner?

Finally, I've read other posts here where the ARB-704 just isn't needed. Any input on that greatly appreciated.

I don't want to lose the built-in Tuner. Having said that, how do I connect this?

Thanks,

Lyman
KB1TJY
« Last Edit: December 22, 2012, 04:11:07 PM by KB1TJY » Logged
N4NYY
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Posts: 4800




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« Reply #1 on: December 22, 2012, 04:34:35 PM »

Lyman, I was working at HRO and we had a similar situation today with an FT-450 and an AL-811. I think the 704 is used as a buffer between higher keying voltage amps like the SB-200 or such, so it does not blow out the keyer. Someone correct me if I am wrong. We were still trying to figure out the cable mess to see if there was a typo or mistake on Ameritron's website. But that was rather frustrating today.
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K1JHS
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Posts: 72




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« Reply #2 on: December 22, 2012, 04:37:20 PM »

I have the ARB-704 and associated cables from MFJ to link my FT-450D to an AL-811. I have not had any issues with either and my tuner still works just fine however I hope you don't think you use the tuner with the amp on do you? The cable does not affect the inboard tuner at all if you are running 100 watts barefoot, it works as it always did.

Hope this helps.... John
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KB1TJY
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Posts: 257




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« Reply #3 on: December 22, 2012, 04:38:18 PM »

Lyman, I was working at HRO and we had a similar situation today with an FT-450 and an AL-811. I think the 704 is used as a buffer between higher keying voltage amps like the SB-200 or such, so it does not blow out the keyer. Someone correct me if I am wrong. We were still trying to figure out the cable mess to see if there was a typo or mistake on Ameritron's website. But that was rather frustrating today.
Thanks. This would seem to be the case the more I read...

Lyman
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N4NYY
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« Reply #4 on: December 22, 2012, 04:39:52 PM »

Lyman, I was working at HRO and we had a similar situation today with an FT-450 and an AL-811. I think the 704 is used as a buffer between higher keying voltage amps like the SB-200 or such, so it does not blow out the keyer. Someone correct me if I am wrong. We were still trying to figure out the cable mess to see if there was a typo or mistake on Ameritron's website. But that was rather frustrating today.
Thanks. This would seem to be the case the more I read...

Lyman

The ideal situation would have been for us to call Ameritron and figure this out, but they are closed on Sat, and I only work on Sat.
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K1JHS
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Posts: 72




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« Reply #5 on: December 22, 2012, 04:40:28 PM »

Oh yeah and I forgot to mention it does indeed go into the tuner port.
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KB1TJY
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Posts: 257




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« Reply #6 on: December 22, 2012, 04:42:11 PM »

I have the ARB-704 and associated cables from MFJ to link my FT-450D to an AL-811. I have not had any issues with either and my tuner still works just fine however I hope you don't think you use the tuner with the amp on do you? The cable does not affect the inboard tuner at all if you are running 100 watts barefoot, it works as it always did.

Hope this helps.... John
Thanks John. I put the external Amp in standby when tuning. Where did you connect the PNP-8M, into the Tuner port of the 450D and then into the ARB? I am not using ALC, btw.

I take it you are not using external power for the ARB?

Lyman
KB1TJY
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N4NYY
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« Reply #7 on: December 22, 2012, 04:42:53 PM »

Oh yeah and I forgot to mention it does indeed go into the tuner port.

Great info! That is what had us confused. I will let my colleagues at HRO know.
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K1JHS
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Posts: 72




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« Reply #8 on: December 22, 2012, 04:49:43 PM »

Lyman, when you tune in standby with the amp on this only applies to the tuning out to the antenna, the amp is in pass through mode. When the amp is in operate mode you actually tune the finals of the amp (poor description) to the load of the antenna. There SHOULD be no need of a tuner between the FT450 and an AL80 (or 811 in my case) as the amp has a "tuned" input to represent a less than 2:1 swr to the rig as long as the bands on both agree with each other.

Hope all of this makes sense..... J
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KB1TJY
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Posts: 257




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« Reply #9 on: December 22, 2012, 07:30:56 PM »

Lyman, when you tune in standby with the amp on this only applies to the tuning out to the antenna, the amp is in pass through mode. When the amp is in operate mode you actually tune the finals of the amp (poor description) to the load of the antenna. There SHOULD be no need of a tuner between the FT450 and an AL80 (or 811 in my case) as the amp has a "tuned" input to represent a less than 2:1 swr to the rig as long as the bands on both agree with each other.

Hope all of this makes sense..... J
Thanks. So you're saying I should be using the internal Tuner with the amplifier on and NOT in standby?

Again, many thanks.
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TANAKASAN
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Posts: 933




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« Reply #10 on: December 23, 2012, 01:52:17 AM »

"Yaesu charges a premium for the use of their 10-pin connector"

Please could somebody explain that bit.

Tanakasan
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G3RZP
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Posts: 4727




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« Reply #11 on: December 23, 2012, 04:18:25 AM »

Lyman,

If the SWR on the feed to the antenna is such that you need a tuner, then you need a suitably rated tuner between the amp and the antenna, as well as an SWR meter between amp and antenna. You can adjust that for a 1:1 SWR with the amp in standby and the internal tuner not working, just using low power from the transceiver. Then switch the amp on and tune it up to full output power.
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W1QJ
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Posts: 1460




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« Reply #12 on: December 23, 2012, 05:14:57 AM »

1. DO NOT have the radio's internal antenna tuner "on" when using it with the amp "in line" or "operating". 
2.  If the amp is "off" or in standby and will not amplifiy, you may use the antenna tuner in the radio to tune the antenna, but turn it off if the amp will be used in operate.
3. As said, if the antenna needs to be tuned because the swr is high or you are using a G5RV then you will need an external tuner that can handle the amplfier power.
4. If it is dertermined that you need an external antenna tuner then you would use it as the "default" tuner in all cases.
5. If you have multiple antennas then the above may be different.
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KB1TJY
Member

Posts: 257




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« Reply #13 on: December 23, 2012, 08:14:46 PM »

Lyman,

If the SWR on the feed to the antenna is such that you need a tuner, then you need a suitably rated tuner between the amp and the antenna, as well as an SWR meter between amp and antenna. You can adjust that for a 1:1 SWR with the amp in standby and the internal tuner not working, just using low power from the transceiver. Then switch the amp on and tune it up to full output power.
Thanks!

Lyman
KB1TJY
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KB1TJY
Member

Posts: 257




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« Reply #14 on: December 23, 2012, 08:17:21 PM »

1. DO NOT have the radio's internal antenna tuner "on" when using it with the amp "in line" or "operating". 
2.  If the amp is "off" or in standby and will not amplifiy, you may use the antenna tuner in the radio to tune the antenna, but turn it off if the amp will be used in operate.
3. As said, if the antenna needs to be tuned because the swr is high or you are using a G5RV then you will need an external tuner that can handle the amplfier power.
4. If it is dertermined that you need an external antenna tuner then you would use it as the "default" tuner in all cases.
5. If you have multiple antennas then the above may be different.
Thank you. I've a Palstar AT2K that I've used for the past nearly two years but honestly it does not seem to have any advantage over the Tuner built-in to the Rig. The latter seems to  be doing fine pulling a near 1:1.

Again, many thanks!

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