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Reviews For: Oak Hills Research 100A

Category: QRP Radios (5 watts or less)

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Review Summary For : Oak Hills Research 100A
Reviews: 51MSRP: 129.95
The Oak Hills Research OHR 100A single band CW transceiver kit
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
W8NLZ Rating: 2021-10-07
Solid & Fun Time Owned: more than 12 months.
I now own the 40M, 30M, and 20M versions of the OHR-100A. I purchased these having tried an Elecraft K1A, Elecraft K2-10, and Argonaut VI. The OHR units, while less capable, are actually more productive. Here are some hints to those who would acquire one used or build their own.

Replace the single turn tuning pot with a 10 turn pot and a 10 turn turns-counting dial.

Acquire a companion digital frequency display. Either the Oak Hills DD-1 or make your own from an eBay 6-digit counter ($12). Just turn it on occasionally to check your frequency.

Align the unit using the manufacturer's instructions. Time required about 45 minutes. You will need a nonmetallic miniature flat blade screwdriver - alignment tool. Peak up the receiver sensitivity. Set the transmit offset to 700 Hz.

Consider acquiring a (used) companion DSP audio filter. I use the Timewave DSP-59+. But an Oak Hills Switched Capacitor Filter works well.

With a good wire antenna and the OHR100A, you will find QRP is no burden in working much of the World. Good luck!


Years have past and I still enjoy my OHR100A/40M. I have now outfitted it with a DD1 Frequency Display, OHR audio filter, LDQ automatic antenna tuner, and OHR SWR/Wattmeter.

I am now in my eighties and operating QRP is like ham radio was in the old days. Key, headphones, and a single tuning knob. All my QRP ops are done portable ... at a picnic table with a dipole hung up in a nearby tree. A 2 amphour battery lasts all afternoon.

The OHR100A is like flying "rudder & stick". No autopilots or fancy glass cockpits. Just him and you and the dits & dahs connecting us. If you have a good ear and the propo gods are smiling, you will be surprised at how well 5 watts does. And you will be pleased.

I like my Oak Hills suite. It is basic, but what is there is good.
KB7PWJ Rating: 2019-04-17
Terrific monobander Time Owned: more than 12 months.
I've had an old OHR 100 (no A) 20M monobander for 15 years now. Can't comment on the build because I bought it second-hand from the builder, but it's been an absolute joy to own. Had it reconditioned by OHR after I bought it and have had 8W forward from it on DC supply (5W on battery) ever since.

Mine has the 10-turn pot and Oak Hills digital display. It's nice to have the added tuning finesse and to know exactly what freq I'm on.

I've always run it without added filters, just the built-in bandwidth knob. An external or aftermarket audio filter would no doubt help. But I get by without undue bother.

Every time I've had to contact Marshal about this rig he's been extremely helpful. The user support is half the reason to own this rig.

Back at the top of the last solar cycle I lived high on a ridge and worked the world with this neat little monobander. I've taken it on the road to many a QTH, set up a random wire and a tuner, and run it off both DC supply and battery with terrific results.

The one mild annoyance is the lack of a built-in speaker. I see where some OHR 100A owners simply instal one (there's room under the hood) and drill holes in the top, but I haven't been sufficiently annoyed to follow suit. Also, I tend to plug in a rechargeable amplified speaker when I monitor the band away from the table, for the added dBs.

Anyway, this is the rig that made me a QRPer. I can't recommend it highly enough.
VE2ZMM Rating: 2016-11-07
pleasant to work Time Owned: 6 to 12 months.
The radio is perfect and complete, very good communication with the seller, turn potentiometer 10 complete the radio.
M0AUW Rating: 2015-12-17
Great Kit Time Owned: more than 12 months.
With intention of building a K2 at some stage, I bought mine to practise some kit building and thought it would be fun for 20m. It turned out to great, good instructions, nice build and a great back up with Marshall, I was very pleased. It does tend to wonder a wee bit on start up but I just get used to that and except it. I could probably fix if so inclined. Great on receive, picks out the weakest of signals! overall good price for a great little rig.
KM4IXK Rating: 2015-06-28
A wonderful radio kit! Time Owned: 0 to 3 months.
I bought the 40m version of this radio. It is my first radio. Not my first kit.. My first radio.

I've built other electronic kits before and this one was a little advanced but I took my time with it and it went together well. There was a problem with some of the supplied chips but they sent me new ones and Marshall Emm is a wonderful person to work with.

So the radio is on the air and I've been using it for several months. So far my longest contact is 4460 miles to france! WOW.

I'm running mine on a car battery. 12.8v gives me 5w. I'm almost never at 12.8v on the battery so my output is usually closer to 4w most days (11.8-12.3v)

The only complaint I have about this radio is.. When I'm answer someone's CQ call I've probably already looked at their QRZ page and saw something interesting about this person that I wanted to chat about but most people only want to talk about this wonderful little radio that is giving a 599 report 1000 miles away on only 4 watts.
KU3V Rating: 2014-06-15
Great Rig Time Owned: 3 to 6 months.
Bought the 40m version already assembled from someone off of on-line. It runs great. Puts out 7 watts which I turned down to 5 watts. I noticed at 7.050MHz with 13.8V it puts out 5 watts and each end of the band it puts out 4.25 watts. The tone is nice, and receiver is very good at being sensitive. Have held a lot of QSOs and received good RST reports back. Has the dial that requires 10 turns or so and the external digital freq counter. I think this rig is a great deal and power is adjustable by way of a pot on the back of the housing. Very good work OHR!

Earlier 5-star review posted by KU3V on 2013-12-13

Bought this off of Ebay already assembled. It is about two years old and for 40 meters. Covers the frequency range of 7005.7 to 7081.1 MHz which is a range of 75.4 KHz. I have had 6 QSOs using 5 watts in the last day out to a dipole up 40 ft. One contact was about 2300 miles away. I receive excellent signal reports. The receiver is excellent since it really pulls in the stations. Also the rig has AF and RF gain dials along with bandwidth adjustment. My rig came with an aftermarket digital readout which is nice. I use straight key with the unit. Very well designed rig. You can't go wrong with this rig. I believe the frequency range can be adjusted higher or lower on the 40 meter band. You can connect your headphones to the headphones jack or a speaker to a speaker jack on the back of the unit. The amplifier has no problem driving your headphones or speaker. Buy one. You won't regret it.
WA4FOM Rating: 2014-05-16
Fun to build. Fun to operate Time Owned: more than 12 months.
Mine went together with only one problem. If
memory serves me, it was a capacitor in the TR
circuitry, which, after a conversation with
Marshall, was willing to replace at no charge.
The radio continues to be a blast to operate;
its receiver is noticeably quieter than most
other single-conversion receivers (which are
already historically very quiet). I attribute
this to the distinct lack of fancy-shmancy

Buy one for each band and have some real fun.
N7AG Rating: 2014-03-18
A BLAST! Time Owned: 0 to 3 months.
15M version, 4.7W. Fun to build, older technology, sounds like a real radio i.e. no artifacts. Suggest 10-turn pot, ready for internal keyed & digital readout. Smooth qsk, filters, fit, enough audio for small speaker. What's not to like.

And Marshall is there to help - ask me.
REMOVED_ACCOUNT_2015_01_09 Rating: 2014-03-02
The Sound Time Owned: more than 12 months.
For those with the DSP Radio's of today who have never heard what a cw signal sounds like with an analog radio this is the radio. For the price it's a great radio and fun. I hear everything that my 590S hears and most of the time better for those weak signals coming out of Asiatic Russia at 10PM. It is so quiet with no hash. The cw filter has much to be desired but for the price it's a great rig. I use a SCAF with mine and that solves any qrm problems.

Have had mine for 8 years and the kit build was great. The few wires are plug in's and it is a clean laid out build. For 150 dollars you will be very surprised. It's my favorite qrp radio.

I can only speak about the 40 mtr rig. Thinking of buying the 30 mtr this coming winter.
KG4LLQ Rating: 2014-01-08
UpDate Time Owned: 3 to 6 months.
I gave a review in October '13 on this transceiver & now I must confirm what a wonderful product it is. Even more important is the OUTSTANDING product support from OHR. Marshall is a true wizard & a credit to the Amateur Radio Community. Just as important to me is the fact that this product is MADE IN THE USA.
Keep up the wonderful work, OHR!