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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: 29 Average rating: 4.1/5 MSRP: $79.95
Description: Single band CW QRP tcvr.
Product is in production.
More info: http://www.mfjenterprises.com
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You can write your own review of the MFJ 93X0 Cub QRP xcvr.

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WA6L Rating: 4/5 Sep 2, 2008 13:53 Send this review to a friend
Best $99 radio kit around  Time owned: 0 to 3 months
I have completed many kits from Heathkit, Elecraft, and Ten-Tec, and the 9380 is by far the easiest kit I ever built. The majority of the components on the board are pre-mounted SMT, so you are left with just a couple of dozen "through the hole"" items to finish the radio. My total construction time was about 3 hours, including alignment.

You can say what you want about MFJ quality, but this kit was top-notch. All the parts were there, the instructions are clear and complete, and the alignment went without a hitch. The little cub worked the first time power was applied to it and has not had a single problem.

If I was going to pick a nit about the kit-building process, it would be that the instructions are not detailed enough concerning winding and installing toroids. This kit is geared toward the first-time builder, and they are probably going to need more help with toroids than anything else. The instructions were complete, but it would have been helpful to provide more information on stripping and tinning the coils.

Once the kit is complete and aligned, you have one nifty little $99 radio. You have to keep that figure in mind, and it is unfair to compare the cub with radios costing much more.

The receiver is impressive for a rig with this parts count. It appears to be very sensitive and the bandwidth is quite narrow. On transmit, my 9380 puts out a solid 2.5 watts and the signal is clear and clean.

The VFO is varactor-based and the drift is considerable when you first apply power. It takes a good 15 minutes for everything to stabilize; after which it is steady enough. This is just an operating hint and not a complaint.

The one complaint I do have concerns the tuning range of the cub. On my 9380, I have a range of approximately 70 kHz. The problem with that is the tuning control is a single-turn 10K potentiometer. With a large range and a single turn, it is difficult to accurately tune in signals. You can go right past a strong signal without hearing it, and once you find it, it takes a very, very sensitive touch to get it centered in the receiver bandwidth.

I don't see the need for that wide of a tuning range for a QRP rig. Half of that would be fine. I think that an easy mod would be to put a 10K resistor in parallel with the pot and reduce the tuning range in half. I will give that a try as time permits.

With that aside, the little cub is a fun project and well within the capabilities of the first-time kit builder. Once completed, you have a very serviceable QRP rig that can be a lot of fun to operate.

73,

John, WA6L
 
K2PGB Rating: 4/5 Jun 9, 2008 14:53 Send this review to a friend
FUN RADIO  Time owned: more than 12 months
I HAVE THE SET OF CUBS. MY BEST DX EVER WAS WITH THE 15 METER MODEL. THE FIRST QSO WAS JA1NUT. WILL NEVER BEAT THAT MILES/WATT AS THE BRIDGE WAS SHOWING ONLY 1 WATT OUTPUT.

GOOD VALUE.
 
WD8DSB Rating: 4/5 Apr 15, 2008 06:29 Send this review to a friend
Great little QRP rig (almost perfect).  Time owned: 0 to 3 months
Yesterday I built the MFJ-9340, and so far very happy with the results. Using a 13.0 volt supply, power output was a hair under 2.0 watts using the stock 2N5190 output transistor. Then installed the MRF-237 in place of the stock output transistor and output power came up to around 2.75 watts, and adjusted it back down to 2.5 watts.

I like the QSK on this rig, and have had good reports on quality of signal (tone). Worked DX last night (YN4SU) from near Indianapolis using my 100 foot attic dipole.

Only major problem was a surface mount capacitor (C33) was standing on end (one end not connected to anything). Broke C33 trying to move it back into position, so replaced it with a standard through hole cap.

Wish the rig had a little more audio volume during the day with weak signals on 40 meters, but it's acceptable. Tried using a little Radio Shack external audio amp and this really helps crank the audio level up to ear banging levels.

You will need a good magnifying glass to read the capacitor values when building this rig, and good strong alignment tools.

My other QRP rig is an HW-8, but I can already tell that the MFJ-9340 has become my favorite 40 meter QRP rig due to its single signal reception (super het receiver), size, QSK, and power output.

Don
 
KC4FKX Rating: 4/5 Apr 7, 2008 13:29 Send this review to a friend
If you are new to kit building, this is the one!  Time owned: 0 to 3 months
This kit went together without a hitch. There were no parts missing and the instructions were very clear and easy to follow. If you are new to kit building or if you are looking for a nice little qrp rig that is not "rock bound", give this one a serious look. I purchased mine along with the "Low Power Communications" book.
As mentioned by others, this is a hot little receiver. My 40M version ended up with slightly more than a 60khz spread along with about 4.5 watts out with the stock PA. I'm rating it a 4 because it comes without a built in keyer like some other rigs do. I used an external Picokeyer. It also has a slight key click but I plan to perform the modification for that found elsewhere on the internet and install a Small Wonder Labs Freq-mite to let me know my exact frequncy. This will be my "throw in the bag" rig for camping and trips to the beach along with a Norcal BLT and doublet antenna.
I've built a host of other rigs such as the OHR 100, NorCal 40, SST, SW+ , Rockmite, DC40, and many others. This was by far the easiest and quickest (due to SMD parts already installed for you) rig to build. I was receiving signals before the alignment process. I'm glad I purchased and built this little rig. It was and continues to be a great experience. It won't matter if this is your first kit or simply another addition to your collection (and this one should be in everyone's), I'm sure you will enjoy building, using, and modifying this little gem.
 
KD8BIL Rating: 5/5 Jan 12, 2008 15:38 Send this review to a friend
First Kit - I'm inspired  Time owned: 0 to 3 months
Received this kit as part of a QRP bundle through ARRL (included the book "Low Power Communication") for Christmas. It was a joy out of the box, there were no missing parts and I felt that MFJ really wanted me to enjoy this radio and learn in the process. There was a lot of extra info in the manual such as instructions on making a voltage regulator which I made and making an antenna as well as hints on how to operate QRP - and they suggested how to mod the thing to get a little more power out of it. 3 negatives were long time shipping, no tools included to align the radio, and a question I emailed to MFJ was unanswered. My cub had poly caps at c6 and c7 and it drifts down upon warmup but not much at all after the first 5 minutes. I finished the kit on Straight Key Night and was amazed at the flury of CW - I have since received respectible reports from NYC and Louisiana from my qth in Dayton Ohio at 2watts running on batteries and through a simple dipole. I have been inspired - Thanks to ARRL and MFJ - this rig sits next to my Heathkit SB-102 and I haven't used the Heathkit since.
 
K9EX Rating: 5/5 Dec 6, 2007 18:46 Send this review to a friend
Great Value with Hot Rcvr  Time owned: 0 to 3 months
I bought the 80 meter version of this kit about a year ago and I just got around to building it at the end of Nov, 2007 (it took me just a few hours to build).

I heeded W5ESE's and KD2DL's collective advice, below, and upgraded the caps and final output transistor to a MRF-237 (NTE341). My unit puts out a respectable 3.5 W and I have really been enjoying using the Cub on the air, making numerous, solid contacts with it in just a few days.

I think 3.5W is just about right to make the QRP experience downright enjoyable - any less than 3W or so and you're definitely in for more of a challenge so I strongly recommend upgrading the Cub's final output transistor to the MRF-237 (NTE341).

My unit does indeed drift, as noted by other reviews, but only when transmitting and only just slightly. Allow at least 30 minutes for "warm up" before you even consider using it and then expect some drift when you transmit.

The Cub's receiver section is extremely hot and outperfoms my trusty Icom IC-718. (Of course, selectivity/strong signal rejection is not nearly as good as the 718.)

Very strong signals overload the Cub and can blank-out the receiver temporarily - you'll get a hint when you start to hear clicks on strong receive signals - about all you can do is adjust the tuning slightly and/or back down the volume.

Despite these very minor issues, the Cub is an easy kit to build, a great QRP perfomer and a superb value at its price point - it's exceedingly simple to use and has an extremely hot receiver. It all adds up to a ton of fun with a "back to basics" sort of feel to it.

Highly Recommended.
 
AC0CL Rating: 4/5 Jun 19, 2007 06:29 Send this review to a friend
Cute...in a Macho Sorta Way  Time owned: 0 to 3 months
I built the 20m version of this transceiver with my dad as and early birthday gift for myself. All in all it took about 5 hours to build, test, and align.

As noted, the receiver drift is pretty bad when you first turn it on. If you warm it up for around 30 minutes it goes away considerably. My complete solution is to leave it on all the time, since it's QRP w/ little current draw it doesn't cost much money, and the drift is not a problem.

I'm using it with an 80ft. vertical up a tree out back. I'm consistantly getting great signal reports. Mine puts out about 2w.

One small drawback with mine is that when the QSK fires up with my keyer, the initial click is deafening unless you turn the volume on the unit down. If you can get use to turning the volume down each time you need to transmit, it's not a problem(I'm used to it), but watch out!

Aside from being a cheap, decent quality, QRP rig. This thing is also incredibly cute sitting on a desk with a set o' paddles next to it.
Overall, MFJ did a fantastic job keeping this thing cheap and easy to assemble.

73's,
Jessť, AC0CL

 
AB7JK Rating: 4/5 Feb 15, 2007 01:43 Send this review to a friend
It works - da!  Time owned: 0 to 3 months
A pretty nice offering from M___ F___ Junk. The 15 meter version puts out a watt and covers 21010 to 21070. It has a thumping sidetone and some drift but I can live with both for now. I'll do the cap replacement when the band improves. I've easily worked a few South Americans in the afternoon with an all-band doublet. It has a nice AGC that the SWL series lacks.

Nothing to wright home about but it works - for MFJ that is saying alot.
 
K3MD Rating: 5/5 Sep 2, 2006 16:27 Send this review to a friend
Works well  Time owned: 6 to 12 months
Purchased th 9340 assembled. It took around 3 months to arrive... I had forgotten I ordered it! It works well, and just as advertised. I do not find excessive drift. It is a lot of fun to operate, and adds to my collection of 6 other QRP rigs. Only the Wilderness SST and the Small Wonders Labs Rock-Mike 40 are smaller.
 
W5ESE Rating: 3/5 Aug 19, 2006 14:39 Send this review to a friend
Fun little rig  Time owned: 3 to 6 months
I built the 9315K for 15 meters to have for
Field Day 2006. The assembly was pretty
straightforward, and the completed rig worked,
but the VFO drift was intolerable.

I studied the schematic and compared it to some
other QRP kits I have built. I replaced the
multilayer VFO capacitors C6 and C9 with NP0
type disk ceramics, and that tamed down the
drift alot. (These are also sometimes called
C0G type caps, and have a very small
temperature coefficient. I used AVX 50V 5%
part #s SR215A151JAR and SR275A100JAR, mail-
ordered from Mouser, which easily fit in the
space on the board).

The drift has not been eradicated completely,
but it's alot less than it was. The radio is
now very pleasant to use.

I hope this information is helpful to others
who may have built or are considering building
a Cub.

Adjustment of the frequency coverage requires
varying a slug-tuned inductor; this is a touchy
adjustment.

The MFJ Cub is a tiny rig, and would work very
well as a camping or backpacking rig.

The assembly and alignment is not difficult.
With a little guidance from a more experienced
builder, it would be an excellent project for
a QRP beginner; just make sure to have on hand
the NP0 type caps for the VFO!

Scott
W5ESE
 
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