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Reviews For: AMERITRON ARB 704

Category: Interfaces, Radio to computer, amp, rotor, coax switch, internet

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Review Summary For : AMERITRON ARB 704
Reviews: 53MSRP: 49.99
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
HI8CJ Rating: 2022-12-04
Work as it should! Time Owned: more than 12 months.
This little thing works like it should. Years of using it with high-end gear to drive Collins or Drake linear amps and I've never had a problem. I really recommend it!
K4SSS Rating: 2022-04-12
I really want to like MFJ, but they keep fighting me! Time Owned: 0 to 3 months.
I just received two new ARB-704's, both with the extra cost ACC Cable (PNP-13D) for supposedly seamless use with Icom Transceivers like my IC-706 and IC-7300, which have very low voltage keying (send) circuitry. I carefully reviewed both the IC-706 and IC-7300 manual, specifically the rear panel ACC Socket and the voltages on Pin 3 (send) are 706: (-0.5 to 0.8v at less than 20ma) and 7300: (less than 0.1v at a max 200ma), respectively.
In typical MFJ (Ameritron) fashion the included instructions were pretty much useless, not even including a schematic. Worse yet, not one word was ever mentioned that a 14 page advanced set of instructions is available on the internet!
My Dad and I, both old school Extra Class operators with over 100 years combined experience between us spent over an hour trying to connect an IC-7300 to a SB-220 without success... We tried everything, too include changing the "TX Delay HF" delay time from from off to the various delay times available (Pg 8-3 of the Basic 7300 manual), since the SB-220 rise time is slower than the 7300's.
We finally gave up and I then researched the internet hoping to find some useful information. It was here that I discovered the 14 page Advanced Manual and after reading it and looking at the schematic I discovered two jumpers on the ARB-704 CB that needed to be properly set for low voltage Icom keying (send) usage. So I opened the ARB-704 case and noticed that the jumpers were not set IAW the Advanced Manual for Icom use, which I am hoping accounts for the seeming inability of the ARB-704 to key the SB-220??
Before making any jumper changes I contacted Ameritron Technical Service. While speaking with them the Tech said that he had just received a new ARB-704 himself and so he opened it and both of his CB jumpers were configured for ICOM use, unlike mine. Go figure, right... So I confirmed with him that both jumpers needed to be placed to the far right (towards the face of the ARB-704) and he said yes.
I haven't had the time to see if changing the position of these two jumpers will now key the SB-220 but thought I'd pass on this information in hope that it might be useful to someone considering buying a ARB-704. I will also add that when using the ARB-704 with a 706/7300 it is a one cable set-up using the PNP-13D ACC Cable, with the 13 pin side going to the 7300 ACC Socket and the other end to the ARB-704 Multi-Port Socket, and since a 706/7300 ACC Socket provides the necessary power to run the ARB-704 Xmit LED, you won't need to use a wall wart to provide power to the ARB-704. IN ADDITION, BE ADVISED THAT THE SCHEMATIC CLEARLY SHOWS THAT THE ARB-704 DOES NOT BUFFER THE ALC IN ANY WAY, SHAPE OR FORM. But since my Dad and I never use ALC anyways this is of no concern to use.
Lastly, I am giving this product a zero due to the complete lack of any "useful" instructional information being provided by MFJ/Ameritron regarding the two jumpers and the Advanced Instructions being available (I know, I should have known better...). As noted at the very bottom of Page 12-1 of the IC-7300 manual: "When the Send terminal controls an inductive load, such as a relay, a counter-electromotive force can malfunction or damage the transceiver." Hence, the need for some sort of switching diode to absorb this possible feedback and the need to change your TX Delay in your IC-7300 or other modern solid state digital transceiver.
I hope this proves helpful and I will consider changing my review if I can get this ARB-704 to work with my 7300, as MFJ/Ameritron claims it will. I'm not perfect and if anyone has some advice and/or a correction to offer me regarding this review by all means contact me. de K4SSS
N7MAM Rating: 2021-02-09
Works but.... Time Owned: 0 to 3 months.
After researching that the FTdx1200 has the same pin out as my FTdx10, I bought the PNP-10MY cable and ARB-704 to interface to my Kenwood 922a. I connected the cable, ALC and Relay jacks. No power was necessary for the ARB704 because the 10MY cable handled that. Well it works, but the red XMIT LED light stays lit all the time if the amp is in OPERATE. If I switch the amp to STANDBY, the LED only lights when the mic is keyed. Nothing was said in the instructions about this being normal so I called Ameritron (MFJ) and Stan didn't have any idea why it would do that. He sounded a little frustrated and told me I could send it back for a refund and that I can design my own. Well if I wanted to do that, I wouldn't have bought this Mighty Fine Junk. -1 star for the LED staying lit and -1 star for Stan's crappy attitude. Thanks MFJ!
KF4HR Rating: 2020-03-20
Excellent safety device Time Owned: more than 12 months.
If you're attempting to use a modern transceiver with an older amplifier (Henry, Heathkit, etc), using an ARB-704 PTT Keying Buffer is a very good idea. Anytime your Amplifier's PTT keying current exceeds the transceiver's PTT current rating, it's buffer time! Or if you just want to be on the safe side, use one. Using an ARB-704 could save you a lot of headaches.
N6BIZ Rating: 2020-03-20
Great Time Owned: more than 12 months.
Mine is over 15 years old .Works flawlessly .Forgot I even had it interfaced.
WB9JOX Rating: 2020-03-20
GREAT HAVE BEEN IN USE MANY YEARS Time Owned: more than 12 months.
N4KZ Rating: 2020-03-19
Works flawlessly Time Owned: more than 12 months.
I've had two of these. Bought one new and got the second used at a hamfest. Used on two different stations. Never any problems.
KE4AMQ Rating: 2020-03-19
junk Time Owned: more than 12 months.
mines stays keyed did it ever since i owned it, mfj junk
W7HBP Rating: 2018-10-28
Using for insurance Time Owned: more than 12 months.
Been using this for several years now. Ameritron AL80B amp and Icom IC-7600 radio. Installed just for insurance. I am using the 7 pin ACC port to run this, my other ACC port was occupied with my W2IHY EQ and EQPLUS for my boom mic. I was able to find the plug and play cable for the 7 pin port from HRO.
The unit has never missed a beat.
AE9DX Rating: 2016-12-11
Cheap Insurance! Time Owned: more than 12 months.
I have one of these little boxes on each of my amps and wouldn't be without them. Very cheap insurance for both the amps and the radios!