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Reviews Categories | QRP Radios (5 watts or less) | MFJ 93X0 Cub QRP xcvr Help

Reviews Summary for MFJ 93X0 Cub QRP xcvr
MFJ 93X0 Cub QRP xcvr Reviews: 39 Average rating: 4.3/5 MSRP: $79.95
Description: Single band CW QRP tcvr.
Product is in production.
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You can write your own review of the MFJ 93X0 Cub QRP xcvr.

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UA1CEX Rating: 5/5 Aug 23, 2016 09:36 Send this review to a friend
Very nice qrp rig!  Time owned: 6 to 12 months
Hi, friends. I have to say, very nice rig. I am very happy. I noticed some drift 9320k and changed caps C6 and C7 to NPO. Now, I forget about drift, but for the first time, if you replace caps to NPO, leave your rig for one hour to train caps.
AF7EC Rating: 5/5 Jul 11, 2016 13:51 Send this review to a friend
MFJ 9340K - Fun little kit!  Time owned: 0 to 3 months
This review is for the MFJ-9340K 'Cub' 40-meter QRP CW transceiver kit.

- - - -
As mentioned elsewhere, all of the surface-mount (SMT) components are already soldered onto the circuit board when you receive the Cub kit. The kit I received was fine *except* for one SMT capacitor (C1) being soldered vertically to the circuit board instead of the normal horizontal mounting. Either the pick-place machine that populated the board with SMT components was having an issue, or the adhesive failed on that particular part during wave soldering. I ended up soldering a wire jumper between the empty pad on the circuit board to the disconnected leg of the SMT capacitor.

All the correct parts were included with my kit ('packed by Carrie' -- thank you Carrie!) and the physical condition of the case, knobs and components was good. There were no visible gouges or scratches anywhere.

The kit took between three to four hours to solder and assemble because I was taking my time and had a few small breaks. I wanted to enjoy the experience but also wanted to finish so I could try out my new transceiver!

The only very small snags I hit were trying to smoothly insert the RF transformers. Because they have so many pins and two tabs, I had to be patient and carefully wiggle them into place. Sometimes I can be heavy-handed, so I tried not to bend or break any of the pins. Thankfully I was able to get them all in without breakage.

The kit requires the builder to wind two small toroidal inductors. For the 9340K, it was eighteen turns on each toroid. Some folks make winding toroids sound like an impossible feat, but it's really not hard at all. The hardest part about it is keeping track of how many turns you've wound and to make sure you wind the wire tight.

When I completed the kit, it was time to align the transceiver. Unfortunately I did not have non-metallic tools for this so I really was not able to dial everything in properly. Some other circuits can tolerate metallic tools, but the Cub is not one of them. I ended up purchasing a non-metallic alignment tool set off of eBay, and *then* I was able to get everything aligned and adjusted the way it should be.

The Cub kit currently does not come with an internal speaker (although it's listed on the schematic). If you'd like to add an internal speaker, the circuit board does have two solder pads available for one. Based on the schematic, the speaker will disconnect when something is plugged into the headphone jack.

- - - -
As mentioned in other reviews, the Cub has some drift when powering up. In my case, the frequency drifts downward until it settles after about ten to fifteen minutes. The drift is pretty drastic, so something I do is to turn on the Cub (when not on battery) and let it sit for a good long time until I'm ready to use it.

You can choose which segment of the band you want by adjusting an RF transformer during alignment. The span on my particular kit is about 70 KHz. I have the top end at 7.070 MHz and the lower end just above 7.000 MHz. Tuning is by a potentiometer and varicap diode setup (not a variable capacitor). The tuning, at least on my unit, is not linear. Everything from 7.070 MHz to about 7.040 MHz is fairly scrunched together while the lower part of the band segment starts to space out a bit. While MFJ provides a medium-sized knob for the tuning control, it really needs to be a bit larger in diameter so tuning isn't so sensitive. You really need a feather touch when trying to tune some of the higher frequencies, and the medium-sized knob is less than ideal.

The sidetone is pleasant to listen to and is derived from your transmitted signal. I wish there was a way to adjust the volume of the sidetone -- maybe MFJ could tweak that a little? The transmitted CW note sounds good, even with my cheesy MFJ straight key.

The receiver performance is adequate. If you are using the Cub for receive-only and are using a short antenna indoors, it's not very sensitive. Using a better exterior antenna or resonant antenna indoors will yield better receiver results. I guess my Heathkit SB-303 has spoiled me as it is a much hotter receiver than what the Cub has.

The specifications state that the Cub puts out about 2 watts. Unfortunately, I do not have a power meter so I can't verify this. I do know that the signal is leaving the confines of my little town as I've seen my signal (intermittently) 310 miles away on a WebSDR server. I am currently using a random wire antenna fed by a homebrew 9:1 UnUn and antenna tuner. My antenna is definitely a 'compromise' antenna, so better transmitting results will be seen when I upgrade my antenna system.

- - - - -
I am definitely on a very very tight budget. I had purchased a sub-$5.00 Pixie 2 'toy' QRP CW transceiver for 40 meters but never made any contacts with it. I *was* wanting a Heathkit HW-8 but they are currently running a bit too expensive for my budget. The open box deal I got on my Cub was just the right price for me. The 9340K is definitely not a fantastic transceiver, but it's fun to build and fun to operate. It's a good compromise rig when you don't have much of an amateur radio budget. The Cub is very good for portable QRP use because it sips power. I use it on my small 12 volt lead-acid battery with great results and it doesn't drain my battery to zero after a session.

If you're looking for a relatively simple and fun one-day QRP project, definitely give the Cub a go!
VA3YG Rating: 5/5 Jan 13, 2016 16:53 Send this review to a friend
Lots of fun!  Time owned: 0 to 3 months
I had a little difficulty with the alignment process for my MFJ-9320. This was my first time building a transceiver. Had previously built a couple keyers and an OHR WM-2 QRP wattmeter.

Say what you want about MFJ, but Richard at MFJ went the extra mile and helped me get a 20m Cub on the air.

I have had a ball with this little QRP rig. If you enjoy QRP and have the patience that QRP requires, you should love this little rig. I've worked all over North America on 20 meters with a small LifePO4 battery, a resonant antenna, an iambic paddle connected to a keyer and a small amplified speaker in place of headphones. 1.5 watts output with 13.2 volts.

The assembly went great for me. Soldering the board was no problem and the instructions were pretty good. Things fell apart at the alignment steps due to my inexperience. I got the rig to receive 100% but no output on tx. Went back over everything two and three times and re-melted as many connections as I could but all to no avail. In retrospect, I would have put the rig aside for a couple weeks and re-visited it later.

After a couple emails, Richard at MFJ came to the rescue and now I use this little rig a couple times a week. The audio with the little speaker I use fills my shack.

I won't hesitate buying another MFJ Cub kit for another frequency. This is not an Elecraft by any means but instead a fun little kit, a learning experience and a QRP rig that you can have lots of fun with.

N8YA Rating: 5/5 Nov 1, 2015 14:51 Send this review to a friend
Great Fun for the $$.  Time owned: more than 12 months
Great Fun in a little package! There is no excuse not to have a radio with you on vacation, camping or whatever!
W3FIS Rating: 5/5 Aug 31, 2015 13:41 Send this review to a friend
Excellent buy + fun  Time owned: more than 12 months
I now own four of the Cubs. 40, 30, 20, and 15 meter version. About 3-4 hours assembly, and another hour testing and alignment. The alignment requires a hex insulated tool. It would be great if MFJ included one, otherwise the instructions are quite complete. Excellent receivers, considering the complexity. The drift issue is there, but just let them run for a while, and they settle down nicely. Good for main QTH, portable, and field use with a tuner/antenna combination of your choice. MFJ also makes a nice amplified speaker (MFJ-382) that is a handy companion piece, if you don't want to use headphone. DO put the optional BNC fitting in place, and as one other poster noted, replace the small tuning knob with a larger one (Radio Shack has one that is a good style match). Use some "marker dots" to show the approximate frequency of the QRP "watering holes," and you are ready to go! Fun to build, and fun to use!
I5EFO Rating: 5/5 May 31, 2015 11:38 Send this review to a friend
MFJ cub 9315 WPX Contest 2015  Time owned: 0 to 3 months
Today I used on WPX Contest my new MFJ cub 9315 with my old Hygain 18AVT/WB GP antenna and on about three hours only I made QSO with 15 DXCC countries.
Beautifull QRP rig !
KF7ATL Rating: 4/5 Oct 20, 2014 19:55 Send this review to a friend
Fun little radio  Time owned: 6 to 12 months
I built the 20 meter version and use it for portable ops outdoors. The kit went together easily without major problems, and worked first time. The only minor problem was during alignment--I didn't have a non-magnetic tool and had to make one. Overall a fun radio to operate. The first time I used it portable, I got a QSO in NJ from UT with decent signal report using a half-wave end-fed wire. I give it a 4 because overall it's a great little rig. Drawbacks include touchy tuning, and warm up time needed to eliminate frequency drift. I was pleasantly surprised at the receiver. It's pretty good for the price.
NG9D Rating: 5/5 Oct 18, 2014 23:23 Send this review to a friend
Easy Does It  Time owned: 0 to 3 months
I got the 40m version from ARRL in a package with an informative book on Low Power Communications. The kit came with more than half of the work already done - all of the SMD were factory installed. The relatively few thru-hole parts, adjustment and mechanical work was done today. I answered W8HOG CQ and he reported the Cub's signal was good. By the way, ARRL shipped within a few days, all part were included and the quality of the kit and instructions (included in the book) were superb. Current kit was supplied with NP0 capacitors and the manual indicated special component selection had been made in the VFO circuit for stability. The highlights of the assembly and that first QSO are on a YouTube video at:

73. Lynn/NG9D
KM5M Rating: 5/5 Aug 8, 2014 22:40 Send this review to a friend
End Result Impresses  Time owned: 0 to 3 months
Have to give the MFJ-9330 Cub transceiver kit a "5" for value/price ratio. It's old-fashioned simple fun to assemble with modern surface mount complexity. The end product exceeded my expectations. Signals seem to pop out of a quiet background. The drift noted by others settles down quickly. The RX portion of my kit came to life and aligned perfectly. But no transmit until I discovered an extra capacitor (C52) the instructions did not say to install. An errata would have saved some aggravation! A nice little performer, needs a stronger sidetone with adjustable level. Vernier tuning would also be an upgrade. Eham please revise the price.
W3FIS Rating: 5/5 Jul 31, 2014 13:00 Send this review to a friend
Solid little radio  Time owned: more than 12 months
I have two of these - 20 and 30 meter versions. Quite sensitive, easy to assemble, and fun to work with. Tuning is a little "touchy," but a larger knob solves that. Drift issue is minimal, IMHO.

73 /paul W3FIS
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