| VE7POE |
Rating:  |
2022-10-04 | |
| A great little transceiver, especially once the relay is removed |
Time Owned: more than 12 months. |
I enjoy fixing and modifying older gear. This unit is extremely well built and has a great receiver. It also sports a very effective Pass Band Tuning circuit. It transmits nice audio provided you use one of the pre-amplified mics designed for the early ICOMs.
I must admit that the band switch relay was way louder than I thought it would be. So soon after I got the radio, the modification to eliminate the relay started. It took some prep time and about $25 worth of e-bay parts. I spent about 12 hours labor building the circuit and modding the filter board. In the end you get to enjoy the 720A's great receiver without the clack clack clack.
I love the tough all metal construction, especially the cast metal front panel. General Coverage receiver is a plus. One weak link in the IC-720A is a very mediocre Noise Blanker. I studied the circuit diagram and changed some resistor values and diodes (PIN) in the NB circuit. It helped some, but still not great. But I think more can be done here.
It is possible to computer control this rig in a limited manner, but not without building an interface. Check the Internet for details. I really enjoy this radio every time I use it. It's just plain fun and performs really well. |
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| VK2JEM |
Rating: |
2017-07-25 | |
| CLACK CLACK CLACK! |
Time Owned: more than 12 months. |
Sold it years ago but I still fondly remember the LOUD clack clack clack of the mechanical relays when band switching or tx/rx.
Was a hot unit in its day, but that day was long ago. Mine had an IC failure and finding a replacement was a nightmare! And those mechanical relays I guess would wear out.
But in its day it worked the world. The old stud bull is put to pasture |
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| DU1FV |
Rating: |
2016-08-06 | |
| For a radio this old, it is great! |
Time Owned: more than 12 months. |
| I tried my ICom SM-8 and was amazed at how good it sounds compared to the HM-7. The other Icom works great with the standard hand mic anyway, so the amplified (set on HI)is now assigned to the IC-720 which needs the amp. It is well matched. I am thinking of a rotary switch relay replacement but I am tempted to try my own version using signals originally intended for the receive band pass filters instead relying on the stepper relay pulses. This should result in a lower parts count conversion, if successful. |
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| ZS5WC |
Rating: |
2015-07-12 | |
| Quirky But Cool! |
Time Owned: more than 12 months. |
This little old square ICOM is an enigma-like a french motor car, -super cool until you have to work on them.., but they just seem to run forever!.
When I first turned on the rig-I kinda leapt out of my chair as the dial light dimmed, and the Stepper relay emitted it's first KLAK!..Anyhow, having learnt that it Has a stepping relay for the LPF filter, and that is was working, I must say tuning around I was reasonably impressed with what I heard.
The rig only seemed to work however with the ATT. switch ON-which was weird, so I traced it to two fried FET's in the pre-amp circuit. I substituted J310's, (Reversed the packages) and damped the gain -910ohm MOF resistors accross the input / output transformers. And Voila!-super hot RX!.
I also added a DC contact wetting circuit for the pre-amp bypass relay, as this would go intermittent often..
The other issue that had me puzzled was the apparent drift of the PLL. Mine drifted MORE than 300Hz from cold, so dug around the PLL--(digging is the right word ad the PLL is BELOW two other boxed modules against the chassis..
Discovered the master XTAL is fine uned by the CAL pot on below the top cover, and the varactor is coupled to the Xtal with an NPO cap-so relaced this cap. with an N750 cap because the Tuning diode has an severy positive temp. co-efficient and the drift was reduced to about 30Hz. I re-aligned the PLL whilst at it, and dropped two cores into the formers which required removal of the two coils and replacing of the one ferrite slug..(Nightmare!)
Anyhow, to further reduce the drift I then added a 50k NTC thermistor to the "CALL" line and lay the thermistor next to the PLL box to sense the ambient temp. result is now about 10Hz from cold and no more twiddling required.
The rig works amazingly well , even on crowded bands!--(I have a IC-7700 to compare with), last project will be to completely replace the LPF board and stepper relay, using my own design-BCD counter, and BCD to decade converter-(no need for a diode matrix) and relays.
Will make a super matching exiter for the IC-2KL amp.
73 de William
ZS4L / ZS5WC |
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| W1DIO |
Rating: |
2014-06-17 | |
| Shadowed by the 751A but Very Good Contender |
Time Owned: more than 12 months. |
| My favorites are the IC-751A and IC-735, but I will add this review of my IC-720A. Please note, I do tune and align my own radios. Lost count years ago. The IC-720A very Robust and Straight Forward HF Radio is constructed of Cast Aluminum Chassis Parts including the Bezel, typical on all early Icoms. Yes, you could pay $Thousands$, for a really fancy radio, but you know as well as I do, that radio will lose allot of luster after that first scratch or dent, not to mention that sick feeling you get when it happens. These radios are a challenge to tune. They are modular design, unlike today’s open board layouts. But once done, they work every bit as well as any new radios out there. Check the Specs, 720A vs. 751A! As for the Band Switch, once aligned, are very reliable. Yes, they are noisy, but so are antenna tuners. It’s all the same principle. It’s simply a band switch, automated. On some earlier radios like Icom, Kenwood and Yaesu, just to mention a few, you did this manually. Some of your best sounding stations out there today are operated this way. Is this method of changing bands any better? It depends on how you look at it. I could go into Insertion Loss, but to make things easy to understand, just remember that the most efficient circuits are simple ones. Good communications is a 2-way street! In order to receive a decent signal, one needs to be able to emit a decent signal. DSP does nothing to a lousy signal but enhance a lousy signal. That being said, the Icom 720A has a place in the “Oldies but Goodies Market”. Don’t sell them short. If you’re looking for a Nice Quad Receive, Small Foot Print and the ability to compete for DX, This is a Very Good Radio! As for what someone posted as a value for these radios, the reality is, one couldn’t afford this radio if it were produced today! Remember folks, SSB and CW is what it is, other Digital Modes come and go. Our Band Plan hasn’t changed much in the past 40 years. Lost a little bandwidth here gained a little bandwidth there. If we gained anything that amounts to something over the years is the QRN. A good receiver, of current production or vintage, properly aligned works the same now as it did in the 70’s, 80’s and 90s. Remember, modes have not changed. DX will always be out there to chase. The question is, what radios do you think will be out there “still working”, in the future? The throw-away or the ones Built to Last! |
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| VA7VRV |
Rating: |
2013-01-22 | |
| Like fine old Wine |
Time Owned: 0 to 3 months. |
| This is my first HF Rig, when I first turned on the radio, it started clicking an clacking like some broken old motor!, My XYL said What is That!!? After reading the reviews on this site I realized it was the rotary band switch. I took mine apart and gave it the clean and lube job, and now it works Perfect! I am very impressed with this old rig, have made contacts all over USA and Canada with good reports. Just using a G5RV and an LDG Z-100Plus auto tuner. Total station cost $550.00. Im Impressed! 73, Ron VA7VRV. |
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| DL1BAZ |
Rating: |
2011-08-15 | |
| Compact and solid rig, nice Receiver |
Time Owned: more than 12 months. |
Got it from an SWL for just 170 Euros (power supply PS15 included). Works as new after realignment, very stable in every way. Nice receiver, beats newer rigs (www.sherweng.com, receiver data). Works very fine with an fl63a 250Hz CW-Filter.
No problems at all with the stepper motor (yes, its "klonky").
Very straight and simple to use.
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| KB0HAE |
Rating: |
2010-10-10 | |
| Good radio but |
Time Owned: 0 to 3 months. |
| I owned one of these for a few months. I was a pretty good radio, but the band switching was very noisy. Everything worked as it should. However, I cannot recommend this radio because of known problems with the electric/mechanical band switching. If the band switching goes out, there are no parts available for repair. |
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| K6LO |
Rating: |
2009-10-30 | |
| Can be a good value |
Time Owned: 6 to 12 months. |
| I had a 720A for about a year with an IRC 270 hz cw filter installed. I found that the receiver handled strong signal conditions pretty well, sounded nice, despite some intrusive circuit noise evident during headphone operation. AM selectivity is too broad for decent SWL work. I wouldn't consider it a good value given the other nicer choices in the same used price range these days especially given the rotary relay casting a shadow. Thankfully owning one 720A and two '701s over the years I have never had that headache surface. |
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| AB5NX |
Rating: |
2009-08-24 | |
| Very happy with the old thing. |
Time Owned: 0 to 3 months. |
| Bought this from a salvage dealer on line.Was told selling for parts only.Looked kinda rusty but not to bad.The seller told me the radio had been under water in hurricane Katrina.Got it this morning and spent 2 hours cleaning and checking out.Powered it up and it came to life,all bands,Full 100 watt output and has good receive.The band changing could wake the dead but I've been told that's how the 720a sounds.I was not looking for a 2nd hf rig but giving it's history and how easy it came back to life I'll keep it.Great audio reports.The only shortfall I found is you can't hook it up to a pc. 73's ab5nx |
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