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Reviews For: Hendricks MMR-40 Transceiver

Category: QRP Radios (5 watts or less)

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Review Summary For : Hendricks MMR-40 Transceiver
Reviews: 3MSRP: 190.00
Sold by Hendricks QRP Kits, The MMR-40 features both CW and SSB operation, the first rig kit in this price class to do so. The reasonably small size, low power consumption and nearly full band coverage of 40 meters makes this rig ideal for back up or emergency use.
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
5R8GQ Rating: 2009-05-10
Forced to pay for expensive enclosure Time Owned: 3 to 6 months.
First of all, the MSRP on the top of this page as I write this ($100) is wrong. $100 was NEVER correct n fact. You USED to be able to buy this rig as a "board and parts only" kit for about $120. NOW you HAVE to buy the enclosure whch jacks the price up to $190. VFO is drifty and receiver performance is not nearly as good as the BITX20A, his 20m rig that IS offered Board & Parts Only. All the parts, andthrough whole plated PC board are excellent, bu the manual needs some work. The font is very small and the drawings not really helpful. Very small section on making a decent mic for it.
The manual also suggests in some places to use a scope or RF probe to solve problems. All kits of this type should be able to be trouble shooted with a DVM and a big rig. Tuning uses a brass screw inside a hand wound coil of very fine wire.
Lining up the three nuts to solder is a drag. Also, whose bright idea was it to put the SWITCH THAT MOVES THE RECEIVER FROM SSB TO CW ON THE BOTTOM OF THE BOARD?
I think this kit was rushed out before the bugs were out (in order to make money and cash in on the prize he won from QST) and it shows. It is not worth $190.
N4QY Rating: 2007-11-15
Very Good Performance Time Owned: 0 to 3 months.
Our radio club has a project contest in December each year, and I chose the MMR-40 for my entry this year. Previous (winning) entries have been the SST 40 meter transceiver and the KX-1 transceiver.

The most complex kit I have built was a Heathkit SB-100 in the 60s when it first came out and have built many other Heathkits as well as some homebrew transmitters. I have also built the 40 meter Stand Alone transmitter designed by Steve Weber. Steve has a very good and unique talent for designing QRP gear. I also have his AT Sprint IIIA, but have not built it yet.

When the kit arrived from QRP Kits, the parts were inventoried and separated. All parts were present. After carefully constructing the unit, and aligning the receiver,it worked just fine.

I was not as successful with the transmitter. I followed the alignment procedure in the manual, but transmitter output was about 1/4 watt on the watt meter instead of the expected 5 plus watts. Listening to the transmitter on a station receiver revealed a horrible sounding signal. I took the IRF 510A final stage off the board, and repeated the transmitter alignment procedure again with similar results.

About this time I was wishing I had bought the Norcal 40A as my project. It will likely be the next kit built.

After much checking and head scratching, I discovered that it is possible to tune T3 and T4 up near 9 Mhz, and the drive signal to the IRF 510A was triple the VFO frequency. With the help of the scope and frequency counter, T3 and T4 were tuned to the 40 m band, and after the IRF-510A was installed again, the output came up to 7 watts. This was more like it.

While testing the MMR-40 with a dummy load, and listening to it with a receiver, the horrible sounding signal was still there. Comments on the Yahoo users group indicated that the transmitted signal would be much cleaner than it sounded in the nearby receiver. However, several cw stations worked commented about the bad tone they were receiving. What was happening was that the carrier and one sideband were both being transmitted. The carrier was not being suppressed adequately so the cw stations on the other end were hearing two tones about 600 Hz apart. Back to the test bench.

This time, instead of strictly following the manual procedure, I put the scope on the output and monitored the signal as the 10 Mhz BFO oscillator was adjusted. The side tone audio frequency signal of 600 Hz wes clearly visible riding on the output signal. Basically, a carrier and 1 sideband were being transmitted. The BFO oscillator was then adjusted until the 600 Hz component essentially disappeared. This meant the BFO was shifted enough that the carrier was being adequately suppressed by the 4 crystal IF filter and the only signal being transmitted was the desired sideband. Power output could now be adjusted to about 8 watts. It would have been very helpful to me if the instructions had mentioned an alternate transmitter alignment procedure if a scope were available or if diffficulties were encountered.

Now the rig was put back on the air for more CW contacts, and no stations have reported problems with the tone. I specifically asked 5 or 6 stations for comments. All said it sounded fine.

The signal still sounded below par in the station receiver, but the received signal on the other end of the QSO was ok. It would have been very helpful if the manual had made reference to this.

I would not recommend the MMR-40 as a first time kit because of the complexity of adjustment and checking required to get a good cw signal. I would also say that a scope is required for proper adjustment and checking of the transmitter.

After getting the MMR-40 properly adjusted, I have been very pleased with the results. The receiver is quite good and more selective than I thought it would be since the IF is wide enough to accomodote SSB signals. The CW audio filter does a good job of narrowing the pass band for cw signals. I have also been pleasantly surprised with the sensitivity of the receiver. The audio output is quite good, and I have used it with an external speaker with plenty of volume. The VFO is quite stable.

In a day of cw operating, I have worked 2 Mexican stations, a Canadian station, numerous US stations and a station in Italy. A Wisconsin station gave me a 599 report and could not believe I was only running 8 watts.

All of my contacts were on cw from North Carolina using an 80 meter Extended Double Zepp at about 75 feet.

Comparing it to my SST, I like the higher power output and the speaker that the MMR-40 has. The SST has better selectivity for cw, but then it won't work SSB either. I may work SSB with the MMR-40 some day after I build a suitable mike.

The MMR-40 will definitely go with me on some camping trips and other portable operations. Right now, I am enjoy using it instead of my several BA stations.

If the instructions had been more inclusive and detailed on transmitter alignment, I would have given the MMR-40 a 5 rating.

I completed my MMR-40 2 days ago.
JL1KRA Rating: 2007-06-26
Best simple 40m SSB/CW transceiver Time Owned: 0 to 3 months.
SSB/CW transceivers in market are big and full of function. But what you really need in QSO is tuning, volume and PTT. The MMR-40 is the one! With this small TRX, you can work IC-7800 and FT-9000. Let them know this simple fun!

The rig arrived to JA soon after ordering. I could built the kit within 15 hours total. With several QRP-kit experience, still the MMR-40 kit gives you new challenge topic to built PTO. Careful winding of PTO and solderling PTO structure to proper position will gives good result. Solder iron more than 30W is recommended to built PTO.

Adjustment is straight forward to receive maxium sensitivity and appropriate TX drive. Be careful to IRF-510 final degrade tranmission spectrum when they drive full.
Receiving performance is typical SA-612 single super het with ladder filter. SSB sounds clear and even you can enjoy 41m SWL(Region3) with wide coverage stable PTO. But without AGC, I always concentrate volume control avoid big sound in small house. Ohtewise another big noise arise from XYL. In this case no way to control. There is no noise-blanker in MMR-40.

For the MMR-40, good mailing reflecter exist in Yahoo-groups. Helping each other, I was helped by them when I had a trouble.

I recommend the MMR-40 for who bored with new YaeComWood. After the Mizuho QRP SSB/CW MX-series are obsolate, the MMR-40 is the best your selection. This is one of the completed, long last design in dual-mode single-band QRP. Need building effort, but worth more than its price forever.