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Reviews Categories | QRP Radios (5 watts or less) | Oak Hills Research 500 Help

Reviews Summary for Oak Hills Research 500
Oak Hills Research 500 Reviews: 8 Average rating: 5.0/5 MSRP: $359.95
Description: The OHR500 is a five band CW transceiver kit.
Product is in production.
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KE6YX Rating: 5/5 Oct 14, 2008 20:15 Send this review to a friend
A very quiet receiver, and a joy to operate  Time owned: 3 to 6 months
I want to preface my remarks by saying that I did not build this rig, but obtained it used. I am the third owner, and now that it is mine, I will keep it forever.

I am giving the OHR-500 a 5 for the following reasons.

It is a QRP rig that does not equate low power with back-packing. I built a KX1 that would do the camping bit very well. Why folks feel those two activities must always be combined is a mystery to me. If I were out back packing, I think I would want all the power I could muster without carrying too much weight. More power would help to overcome the antenna limitations that go with that kind of operation.

I have to believe that this is one of the quietest CW rigs in existence. I can set the controls to listen to a weak signal, and then switch the rig off line with my coax switch. The result is dead silence even with head phones. The only noise you will ever hear is what is coming from the antenna. No digital noise here!

All the controls you need are there on the front, and easy to work with because it is not packed into a tiny cabinet like most QRP rigs. Having both audio, and RF gain is a real plus. It is also nice to have the ability to switch the AGC off when needed.

I do have some nits to pick. It should have come with a digital frequency readout built in. In my case I built the FCC-1 kit offered by AMQRP, and that solved the problem.

Aligning the rig is not hard when following the manual. The result is a nice signal that all of the contacts I have made seem to like. There is one hidden problem. If you use a voltmeter as suggested when aligning the rig, it will work fine, and sound fine, but there is a good chance you will have trouble getting a frequency counter to work with it as I did with the FCC-1. The problem is the oscillator board put out a signal on some of the bands that was not a pure sine wave. It had some odd bumps in the pattern. No one will never hear it on the air, but it prevented both my FCC-1, and my B&K bench frequency counter from syncing on those bands. I recently went back in and aligned that board again using an oscilloscope to clean up the wave form on each band. It only took a few minutes, and now the FCC-1 reads out perfectly!

In case you are thinking that I have never compared the OHR-500 to a modern rig with a “really good” receiver, I want you to know that it is sitting on my desk next to a Ten Tec Corsair ll, and a Drake 2B. I can switch between all three. Having the ability to do A/B tests is the reason why I ended up getting rid of a Ten Tec Argo V a few years ago and a new ICOM 746 Pro a few months ago. They all had noisy receivers, and were a PIA to operate.

If you can build an OHR-500, or do as I did and find a good used one, you will never find a better QRP CW rig for your home operation. I just cannot wait for solar cycle 24 to improve.

N2UGB Rating: 5/5 Jun 9, 2008 03:16 Send this review to a friend
Wonderful, especially after re-alignment  Time owned: 3 to 6 months
I purchased the 500 used, I think third-hand, over-priced and needing alignment. I sent it to Marshall Emm and one of his contractors at OHR did a fine job of doing just that and at a reasonable cost.

The OHR 500 is really a great, minimalist QRP transceiver. Mine is very, very nearly...oh heck, call it 5 watts output on 20 and 30 meters...higher on 40 and 80 meters...lower on 15 meters.

The front-end is quite sensitive and reasonably selective. CW signals are sharp, clear, and well defined. An out-board audio filter might be desirable at some point. The CW side-tone has a bell-like quality that I find quite pleasant.

Signal reports have been very good with no reports of key-clicks or chirping, and now, drift.

Since the OHR alignment, after a couple of minutes, the rig is drift-free, and the final transistor oscillation that occured as it approached full output, is no longer evident.

The size begins to approach that of a QRO rig, and that suits me fine. This is no mini QRP radio to tuck in your pocket. I wouldn't think of back-packing it, though as a field-day QRP station, it would do well. The controls are conveniently laid out and easy to manipulate. They are decently sized. You have something to grip.

I will definiteley be maintaining and keeping the 500. I couldn't help but think, what a nice, uncomplicated rig for someone who may have some physical problems dealing with tiny controls and buried menus.

KE7HPV Rating: 5/5 Feb 16, 2007 13:52 Send this review to a friend
Very impressive radio  Time owned: 0 to 3 months
I have just finished building an OHR 500 with the DD-1 frequency counter and the RF load.

First impressions: The OHR 500 has a fantastic receiver. I have owned modern rigs like the TS-480 and FT-817 but for it's intended purpose the OHR is as good if not better on receive than either of these.

Building was daunting at first but once you get into it the time just seemed to go. There are 35 toroids in the kit and this is probably the most stressful part of the build. If I was doing it again I would have them pre-wound. Total time for 3 kits was about 10 days.

There were 2 wrong value caps and 1 missing cap in the kit but a quick email to Marshall Emm had them in the mail same day. They arrived promptly and it gave me time to finish the toroids!

No major problems with alignment. I did it myself and is fairly easy if you have had a little experience with older equipment. It reminded me of calibrating an FT-101. I does help a lot if you have a scope and a calibrated frequency source - I used a simple xtal transistor oscillator.

I can get around 7W on 80m, 5.5W on 40m, 5W on 30m and 4.5W on 20m. 15m is low on my radio but I am convinced this is my fault not the kit!

The TX/RX changeover is noiseless and is just perfect. Way way better than most high-end rigs.

Adjustable TX power on the front panel is great and allows accurate control down into the mW level.

I find the filter control does make a difference and can really help with the weaker sigs.

Frequency stability is good once you let the rig warm up. For this reason, don't bother calibrating it until it's had at least 30 minutes. LC VFO designs will always have some frequency drift but once warmed up I can leave the OHR on 14,075 and copy the ARRL bulletin without retuning.

Definitely recommended is the DD-1 counter. Neat little shack item and works very well with the OHR. It can be a little tricky to get it to lock properly on all 5 bands but a bit of trial and error (adjusting sensitivity pot) will get it working.

I will update this review in a few months after I have given it some serious use!

ADAM12 Rating: 5/5 Jan 5, 2003 18:01 Send this review to a friend
Up there with the K2  Time owned: more than 12 months
I built this little gem in the summer of 2001 and still love it. It's definitely a keeper; especially since the kids helped me build it :)

Apart from its reputed top-notch performance and also that of its predecessor, the OHR-400, I was attracted to the 500's nostalgic looks; you'd almost expect to see the warm glow of tubes behind that spartan front panel :)

Don't let that fool you though, this is one very hot little radio with a better receiver for its dedicated purpose (CW) than most commercial rigs.

I also bought the optional keyer, RF (dummy) load, WM-2 Watt Meter and DD-1 Digital Display with the OHR-500 which together make a really neat little QRP station for the home shack.

The printed circuit boards are all of excellent quality and all parts were present and correct in all of the kits. Each kit's manual clearly leads you step by step through the building process.

Apart from a Tuna Tin 2 (which has about 12 components in total), these were my first kits, so don't be intimidated by all that wiring in the OHR-500; the manual makes it all very easy with the color-coding. There are a lot of torroids to wind though and that's probably the only daunting part. 'Easy enough, just a chore.

I'd strongly recommend that you get a 15 Watt pencil soldering iron with a fine tip and some fine 2% silver solder. Radio Shack sells one and the soldering iron tip cleaner they also sell is great stuff. You'll want good wire strippers too. OHR's sister company (Milestone Technologies) also sells all the tools you might need.

I had OHR build the DD-1 with the intention of using it to align the OHR-500 (you can also use the DD-1 as a general purpose frequency counter). Unfortunately, I wasn't getting the readings I was looking for on a couple of bands so decided to send the 500 off to OHR for alignment (I'd figure this $80 or so into the cost if I were you as many of the other builders I've read about also sent theirs to OHR for alignment once built).

Anyway, it came back working beautifully and puts out 8 or 9 watts out on 80m, 7 watts on 40m, 3.5 Watts on 30m!?, 5+ watts on 20m, and about 3+ watts on 15m. I'm not sure why 30m is low and have subsequently re-done the alignment myself but still can't get more than 3.5 watts out on 30m though. Maybe a wrong component value or one too many turns on a torroid!?

Anyway, the rig is very quiet as it uses a traditional air variable capacitor tuned VFO instead of a modern frequency synthesizer. Because of this I guess, I've heard people say OHRs are "drifty", but this has not been my experience at all. It's plenty sensitive too and the (diode-switched) QSK is just right, a little "softer" than Ten Tec, but fast recovery nonetheless; I prefer it to Ten Tec full QSK, which I find distracting. The 500's side-tone is a joy and sounds like a note being struck on a piano, really! Pitch and level can be internally adjusted. Transmitted signal reports are always T9.

Dial calibration is not bad for analog, but I wouldn't want to be without the DD-1. Bandwidth is fixed at around 400Hz (XTAL filter) and although there is also a switchable audio filter, it really is a waste of space as you'll leave it in circuit all the time (it doesn't affect the bandwidth, just removes the *very* slight electronic hiss and peaks the signal so why switch it off?). I've very rarely had a problem copying any station I can hear with this fixed bandwidth, regardless of band conditions or crowding. AGC is fine for levelling strong sigs but doesn't seem to boost weak ones; it can be switched-off from a front-panel switch.

I did come across an interesting feature when using my vibroplex bug with the rig. With the bug plugged into the straight-key socket on the rig, on keying the bug, I was getting one dot out for every four dots the bug was making, very strange! I asked OHR via email what was going on and they told me that it is an undocumented feature of the rig/keyer that the straight key socket actually goes into the keyer circuit (as does the separate paddle socket). Apparently the keyer circuit has a straight-key mode which, when you have the keyer speed set to approximately the same speed as you're sending with a straight key, actually modifies your hand-keying to improve dot-dash timing thus improving a choppy fist! Cool! Obviously, this feature wasn't particularly intended for use with a bug though, so when using a bug, just set the keyer speed to maximum and it won't interfere with your swing (or your choppy sending) Hi Hi. With a paddle, the keyer is flawless.

Every other (commercial) rig I've had, had some deficiency or other, but apart from 30m being a little low on *my* 500, I can't fault this little rig. Oh all right... an S-meter would've been nice :)

No complicated menus, double-purpose buttons or dual VFOs to confuse you, no software to hang-up nor useless memories, no extra filters nor dsp units to buy (not necessary). It just does what it's supposed to do without fuss or complication.

If, like me, the complexity of operation of the K2 and FT-817 leaves you cold but you don't want to compromise on performance, buy an OHR-500. I doubt you'll regret it !
WD4HLO Rating: 5/5 Sep 10, 2001 13:55 Send this review to a friend
Best QRP Value  Time owned: 0 to 3 months
I just bought this little gem from a Ham in North Carolina who did an exquisite job building it. The receiver on it is unbelieveable! It is much superior to my TS-520S or HW-101. I have worked more countries in the week that I have had this radio than in my whole previous ham career. My antenna is a parallel dipole for 20/15. I have been able to work almost every station that I have called running less than five watts. My only complain is that I wish the digital display was integrated into the transceiver case instead of being a stand-alone unit requiring a separate power supply.
VA3UT Rating: 5/5 Jun 8, 2001 18:07 Send this review to a friend
Excellent  Time owned: 6 to 12 months
I bought OHR-500 late last year and built it over the holiday season. It was a pleasant experience and everything went through smooth. I had lots of fun building it and I spent about 4 nights, about 4 hours every night. The number of toroids I had to wind was 37 (if I remember correct), and I did it as one shot. After the completion, I sent the unit to Marshall for proper alignment because I wanted to have it as good as it can get. The OHR-500 came back and I was amazed with its performance. It is extremely quiet and CW sounds really well. I checked the waveform of this OHR-500 with my friend's scope and it generates perfect sinewave.

I was really surprised with it quiet receiver and signal just comes out. Even when there is lots of atmospheric noise, it is much quieter than my other radio.

If anyone wants to build own radio at a reasonable cost, this must the best choice. 5 band coverage is excellent for station use. It is a bit too big for camping, but I could manage it. I wish it has a built-in speaker so that I don't have to use my headphone or external speaker, and that is the only drawback I can see from this radio. Digital display must be nicer, but it is OK without.

I have K2 and other small QRP kits as well. For receiver quality, I give more points to OHR-500, but K2 gets more points for its nice features. However, I like the classic feeling of the OHR-500.

Communication with Marshall at Oak Hills Research is a joy. I have no connection to Morse Express (OHR). I am just a happy customer.
KB7OEX Rating: 5/5 Jun 7, 2001 03:05 Send this review to a friend
Immensely Pleased!  Time owned: 0 to 3 months
Back in March I submitted the "first half" of this review. In short, that review said I was quite impressed with the service and products I had received from Marshall Emm of Oakhills Research. That service was one of the reasons I decided to buy the OHR500 kit. In the last two weeks I finally got the time to build the kit. The kit is finished and I would like to share my final impressions in an effort to help any would be QRP types looking for a project or even a first kit. To help you evaluate where my own opinions are coming from, I will tell you that I have a K1, K2, Ten-Tec Omni-C and a second K2 which I will begin to build shortly. I have been in HAM radio less than a year and these rigs serve as reference points for me. I have zero technical background and my impressions are from what I experience in the shack....not from spec comparisons. In a nut shell: this is a wonderful, wonderful kit and a very, very impressive rig. I built it and put it on the air with zero problems (well, one or two questions did pop up because of my own ignorance). I can make this rig as quiet as my Ten-Tec and much more. Often you can make the background noise TOTALLY disappear while the CW signal comes out clean as a whistle. I really find it quite remarkable. So far I can pick up any signal my K2 can pick up (and believe me, the K2 can pick up signals). The rig has what I call a "classic" feel to operate. It is as user friendly as you will ever see. It has simple controls and incredible results. If you are distracted by rigs that have tons of "bells and whistles" I urge you to reconsider what the essence of a HAM is: quiet reliable communication and the ability to pull out weak signals. That's what this rig does very well. If you are a first time kit builder, don't be afraid of this project. I built it without a hitch. It does look complicated, but all you have to do is read and know how to solder. If by some small chance you do have a problem, Marshall is fast and responsive to all questions. I am quite proud of this rig and think it is a MUST for any QRP stable. BTW...get the Oakhills watt meter to go with already know its a classic QRP necessity!
KB7OEX Rating: 5/5 Mar 16, 2001 08:38 Send this review to a friend
Service is where you start!  Time owned: 0 to 3 months
Well, I've noticed there are no reviews on the OHR500, so I am adding a somewhat premature review. I have the kit and have browsed thru the manual and, of course, scrutinized with anticipation the parts, boards, and enclosure items. All very nice and well done - it's quality. I have not started building it yet because I am currently building a K1. I already have the K2.

Two questions might come to your mind: Why would I buy an OHR500 if I have the current rage/Rolls Royce already - the K2? And - why would I be giving a review at this point when I have not even begun to build the OHR500?

Let's tackle the K2 question first. There is little doubt that the Elecraft K2 is truly the current Rolls Royce of QRP rigs. My K2 was built for me because it was my first radio. I had it shipped directly to a new friend/builder who did a masterful job building it. I had never built a kit and did not believe I was qualified to build it. It truly is a Rolls Royce and I love it. Elecraft is a great company. With more confidence I am now building the K1. Why would I build an OHR 500 after this? It's simple, I want to build a multiband CW rig and I personally like the simplicity, look and style of the radio. I like it because it is a DIFFERENT radio from the K2 and it will be a DIFFERENT building experience from the K1. Variety is the spice of life. This is simply personal preference. More importantly, to those who read this, is my experience OHR/Marshall/Emm - which leads into question 2.

Why am I doing a review whan I have not built the kit yet? I'm doing so because I believe that in great measure buying a kit should include great consideration of WHO you are buying it from and how you are treated. My first contact with OHR was actually thru Morse Express when I ordered my Schurr Key/absolute jewel. When I called OHR I heard a familiar voice and thought I dialed the wrong number - but no it was Marshall Emm. He owns both companies.

I had read about the OHR watt meter in a QRP book et al. I chatted with Marshall a bit, then ordered the kit. I figured that anybody who handled Schurr keys had to have pretty good taste! It turned out that the kit is excellent as a first kit and gives you an indispensable tool for your workbench or shack. I had one problem, which was caused by my in ability to read Marshall instantly and patiently pointed it out (via email) and I was done. I've never had to wait more than a few hours or the next day to get a response from Marshall - at least that I can remember. When you are new to kits this is IMPORTANT. The watt meter was my first completed and functional kit and I was jazzed. Then I ordered the L/C meter that Marshall distributes - after talking with Marshall on the phone about it and having it recommended by a very knowledgable builder.. My objective was to compliment my bench with test tools. I built it in one night and had no problem. This was a pretty good track record - three products - excellent communication and results on all of them. I went one step further and bought a Logikey (not the kit) from Marshall. It is probably one of the best additions to my shack so far. Again, I chatted with Marshall and had done a bit of reading about the unit before hand. My experience with Marshall on these products was VERY IMPORTANT in my decision to buy the OHR 500. Also I liked the price - one price and you have everything. Now, let's talk about "building philosophy". I'm interested in learning about how things work and I am starting from scratch. However, learning how radios work from scratch is no small task. When I build kits I get so excited about building the kit that I want to complete it before I thoroughly understand EVERYTHING about how it works. So I've decided that you learn what you can from each project, but avoid getting so bogged down in learning exactly how each little cap/resistor combo etc works - otherwise it stops being fun. I think OHR thinks the same way - so they don't go overboard trying to give you a complete radio course in one kit. \

They DO work hard at making a manual that gets you thru the kit successfully. They want to see you finish the kit and feel good about it. If you do have a problem - which in my experience with their manuals is not likely - just send it up to them and avoid any excess frustration.

Perhaps this sounds more like a sales pitch for Marshall Emm and his two companies. So here's the reminder - I'm in no way connected with Marshall Emm or his companies. I'm simply someone who has been treated very well and very much enjoyed these products. I intend to supply further installments once I start the OHR500 - if the experience is good or bad I'll let you know. But for right now, I think this info is worthwhile to all those who have wondered about the OHR500 and might be anticipating buying it. Service is where it starts.

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