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Reviews For: MFJ 93X0 Cub QRP xcvr

Category: QRP Radios (5 watts or less)

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Review Summary For : MFJ 93X0 Cub QRP xcvr
Reviews: 40MSRP: 79.95
Description:
Single band CW QRP tcvr.
Product is in production
More Info: http://www.mfjenterprises.com
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
14404.3
W5ESE Rating: 2006-08-19
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
WA8MEA Rating: 2006-01-12
My 80 meter version... Time Owned: 0 to 3 months.
Since I build stuff all the time, I didn't really care to be hassled with having to put this together during the holidays. So I paid the extra $$$'s to have it arrive wired.

What a dam nice little rig for the money! I mean, we can sit here and be critical all we want. But for around $100, we get a pretty nifty transceiver!

I get about five watts output from my 80 meter version. Someone answered my very first CQ. He couldn't believe I was QRP.

The receiver is better than my Sangean 818 w/ dipole antenna.

Yes, there is that 30 minute warm-up period to avoid drift. But....I turn it on right away when I came downstairs to the shack. And before I know it, a half hour has passed and she's stable as a rock. At just a few ma's of power, I leave the lil' cubby on all day.

Hats off to "Mighty Fine Junk" for another low cost piece of FUN.....

73, Bill - WA8MEA
http://HamRadioFun.com
K2JN Rating: 2004-04-16
Good kit but poor customer service Time Owned: more than 12 months.
I purchased a 9320 kit in the spring of 2000 as a birthday gift to myself. It took me roughly 4 hours to install all of the parts including winding two toroid coils. Installation was fairly easy since all parts are soldered to a printed circuit board (no wiring is required) and all of the surface-mounted components were already pre-mounted. I encountered only two issues in construction; the SPDT switch pins were bigger than the circuit board holes and I was missing a 220 pf multiplayer capacitor. A little bit of reaming with an Exacto blade solved the board problem. The missing part was not so easy.

I wrote MFJ an email about getting a replacement and they responded saying that the capacitor would be mailed that day. However, it never arrived. Follow-up emails were met with silence since they refused to respond. Eventually, I picked up a replacement cap while on a vacation trip. I’ve owned several MFJ products over the years and this was my first experience with customer service. I was disappointed over the incident -- even to this day.

Once the kit was complete, I found that performance was as expected. There is a slight RF drift but it tends to stabilize over time. Overall it is a fun kit to own and operate. I hope customer service has improved.
KD2DL Rating: 2001-11-12
9317 & vectronics 1320 1330 Time Owned: 3 to 6 months.
I just built the MFJ Cub for 17 Meters. Two things worth mentioning are the radio
drifted slightly lower in frequency untill about 30 minutes warm up time.
Bad enough that I replaced c6 150 pF with a silver mica cap instead of
the supplied 150 pF multilayer capacitor. That cut the drift down enough
so you don't have to chase your qso up and down the dial after a 5 minute
warm up time. I don't think the drift will ever be totally eliminated with this design
but,you can improve it significantly. I also changed the output transistor to a
MRF-237 (NTE341) or (2SC1947). Actual part was the MRF-237 and was able to
get about 2 1/4 watts output vers the 1.5 watt output with the stock 2n5109
supplied with the kit. In comparison I also built the transmitter bords from
Vectronics (also now MFJ) the VEC1330 and VEC1320 30 and 20 meter
cw 1 watt transmitters as I already have a nice travel radio to recieve with.

The vectronics kits were much more stable with little or no drift.
The MRF-237 also increased the output of these bords by 20-40% depending
on freq of operation. The MFJ cub for it's size a great travel rig for
17 Meters; however, for 20 and 30 meters I would probably build the vectronics kit
instead as it is far more stable but only offers 10 Khz tune range in the CW band.

The 2n3553 transistor did not increase output sufficiently to justify swapping them
as suggested in the MFJ manual. The gain is appearently not as high as with the MRF
family of transistors... and obviously the higher in frequency the less power they all
put out. (your milage may vary) 73 and Good QRP DX de KD2DL
M0CQG Rating: 2001-09-10
Fun little radio Time Owned: 6 to 12 months.
I bought the 40m version of this tiny QRP rig. It took an afternoon to build and test - a very easy project, certainly within the capabilities of any beginner. I did feel a bit of a fraud just 'finishing' the radio off - it comes with all surface mount components pre-installed; you just install the bigger discrete items and hardware. Alignment was straightforward, and the rig was ready to use within a couple of hours or so of opening the box. On air, the RX performance was surprisingly good, given the relatively simple design. The TX signal received good reports too - no chirps or clicks were noted. After alignment I measured maximum power output at around 2 watts, but adjusted it down to 1.5 watts out of kindness to the amplifier stage. Even with my indoor dipole, this proved enough to work UK and European stations with ease.

Things I liked about the Cub:

- Nice quick project, perfect for a Sunday afternoon or weekday evening
- Great quality board and components
- Compact and well laid out; looks cute!
- Performs well for a simple design
- AGC is excellent!

Things I wasn't so keen on:

- On 40m version, VFO knob tunes 'in reverse'
- No RIT (though mods are available to implement this)
- As standard, comes with 'phono' antenna socket (I fitted a BNC later)
- VFO drifts rather badly until fully warmed up (OK after that)
- Paint finish on lid was rather basic!

Although not perfect (what rig is?), this is a good little kit. I sold my 40m Cub, but was smitten enough that I'll probably build a 20m version some time soon.
G4GZG Rating: 2001-08-27
Marvellous little rig !! Time Owned: 6 to 12 months.
I bought the 40M kit last December, on an impulse and put it together in about 4 hours. I nearly wrecked it when testing it by connecting the power the wrong way round, so the protective cct definitely works !!


I found it easy to build and all the components were there as described. Mine put out about 1.5W and I was going to adjust it but never got round to it , and run it at 1W O/P.

On air its a dream - -if you can live with the lack of Bandspread tuning - -I grew up with old WW2 surplus rx where 20M was half a turn on the knob wide !!
I grew to really like this little rig and worked some good 40M DX - - VK, UA0, W1, VE3 and PY2 using the Cub and a 40 M dipole up about 25 feet. I also had a lot of good EU contacts on it., and every contact brings a smile to my face when I remember the power I am using.

Some other users complained that their Cub VFOs drifted, but mine is perfectly stable after a few minutes warm up.

MFJ have a winner here - and the semikit idea is great for the returning homebrewer - like me .
K8RJA Rating: 2001-02-18
Good performance Time Owned: 3 to 6 months.
The stock Cub is a pretty good performer, but a few mods make it into an excellent performer. The advertised QSK is not for real and any change in power supply voltage also changes the frequency.
I have added the following mods to my Cub:
1. Larry East's mod to refeed Q4 with regulated voltage to prevent frequency shift with power variations.
2. Larry's RIT circuit.
3. QSK mod by Rick Littlefield.
These were all found on the Cub user's group page and have made the Cub a Super Cub.
G3XBM Rating: 2000-09-02
Excellent QRP rig Time Owned: 0 to 3 months.
Really pleased with my MFJ9315K (15m) cub. Went together with no real problems and performs very well here in Europe. So far, with just a wire dipole I've managed 8 QSOs in just a few hours including 1 across the pond.

Receiver is quiet, selective and free from obvious signs of IF breakthrough or spurious responses.

MFJ have a winner and I am well pleased.
W2RBA Rating: 2000-03-23
17 Meter MFJ Cub is great little semi-kit Time Owned: unknown months.
I've assembled the 17 meter version of the Cub and can report that it works as advertised. It takes about 4 or 5 hours altogether to finish the kit -- it includes a pc board with numerous SMT (surface mount technology) parts already installed and you just have to stuff 50 or so parts for a working transceiver. I commend MFJ for ensuring all the parts were there -- nary a single part missing or extra! The alignment of the VFO was a bit tricky and you should not use an alignment tool with the tiniest bit of metal in it, but except for that problem (rectified by a quick jaunt to a RS store and $2) the radio tuned up nicely. I'm getting a full watt output on 18.7 MHz and that is adjustable by means of a board-mounted pot for which there is a hole in the top. It's a very basic receiver and the Small Wonder Labs DSW series is nicer (for about the same money SWL DSW offers digital tuning and RIT plus a built in keyer) but the Cub is offered for 17 and 15 meters whereas the DSW is not. All in all the kit is highly recommended for the QRPer or someone who is interested in QRP. I've made a few contacts, though with my 80 dipole (and a tuner!) none has yet been been DX. I'm sure I will work some when I get a 17 meter antenna up.
N1IRZ Rating: 2000-03-06
A Lot of Performance in a Very Small Package Time Owned: unknown months.
This is a solid, impressive rig, particularly considering the price and the amount of effort required to assemble the kit. While it uses surface-mount components extensively, those are already installed on the board, and the customer finishes the assembly by installing the through-hole components, pots, etc. This gives you a rig that provides the benefits in size and performance offered by surface-mount technology but with an ease of assembly that requires only modest electronics experience. For this reason, I would urge nearly anyone to buy the kit version and enjoy putting it together. I assembled mine in about four hours over a couple of nights. Once completed, the rig performs well, with a sensitive receiver, full QSK, and a nice-sounding transmit signal. I built the 20-meter version and my first contact was a UA4 in Russia! The 20-meter version is advertised at 2 watts output, but mine puts out about 3 watts. This is adjustable down to no output at all. Some peculiarities include the RCA jack for RF output (but a pre-drilled hole is provided for a BNC jack) and a mandatory stereo plug for audio, but these are easily accommodated. I found the rig to be stable, showing no noticeable drift.

Overall, this is a great QRP rig with a lot of performance in a very small package. If you've been wanting to build a QRP kit but worried about your own skill or getting an inferior product when you're done, take heart -- this rig is fun to build and a great performer on the air.