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Reviews Categories | QRP Radios (5 watts or less) | Mizuho P-7DX Help

Reviews Summary for Mizuho P-7DX
Mizuho P-7DX Reviews: 3 Average rating: 5.0/5 MSRP: $200 as a kit, $255 factory assem
Description: 40 meter CW transceiver
Product is in production.
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JO1ACW Rating: 5/5 Dec 5, 2003 00:17 Send this review to a friend
Perfect QRPp CW Transceiver  Time owned: more than 12 months
I got P-7DX in 1992 Nov. which was 1st lot delivery. Just before that, Mizuho supplied "P-7" for Hamfair '92 with special price. This P-7 was almost same specifications with P-7DX but not painted case. I wanted get P-7 but lost chance due to limited quantity.
I have been using P-7DX more than 10 yrs but I have never had any problem, I am using it for QSO on every weekend with JA's QRPp stations and could receive very weak signal same as commercial transceiver.
P-7DX is very famous among JA QRPers and still many QRPers are waiting next chance to get it.
I had chance to talk with Mr. Takada before and was told that if he received some inquiry and if it will be enough quantity to prepare, maybe will supply temporally with limited numbers.
Back to 3 - 4 years ago, I saw advertisement on JA CQ magazine, Mizuho announced to sell some sets of P-7DX & P-21DX but needed booking.
(Nowdays, it seems more difficult to buy new one.)
Hope you could get P-7DX and will enjoy thrilling QSO with QRPp.
KU4QD Rating: 5/5 May 6, 2003 01:32 Send this review to a friend
Brilliant little portable CW rig  Time owned: 0 to 3 months
I, like the previous reviewer, have been fortunate enough to find a recently built P-7DX. Mine is the later version, with the tiny internal speaker and the optional PF-1A audio peak filter installed. Early ones did not have the internal speaker.

The P-7DX is very small, very compact, and runs on 6 AA cells. It can also be used with an external 9.5V supply (the Mizuho PS-2 is the matching unit) or with a 13.8V supply using the optional PM-1 DC to DC converter. The rig is beautifully made and solidly built. It has the essential features you need on a portable CW QRP rig: RIT and an RF attenuator.

The radio is VXO controlled and can cover any 30kHz in the 40m band. I have the default 7.000-7.030 crystal in mine. The QRP calling frequency is 7.040, so if you want to operate there figure on adding about $23 to the cost of the radio for a genuine Mizuho rock. Mizuho crystals use a proprietary cut and any I've gotten from a third party were either off frequency or didn't give me full range. There is plenty of activity below 7.030, so if you have an extra class license (or the equivalent if you are outside the U.S.) you may want to just leave well enough alone.

Like the previous reviewer I found my radio to be precisely and accurately calibrated from the factory. Tuning is smooth and the tuning rate is quite comfortable. The received audio is excellent through headphones or an external speaker. The internal speaker is truly tiny and sounds it. I suspect operating for a long period of time with just the internal speaker would be quite fatiguing.

I had no problems making contacts with the rig through a dipole around 30 feet (10 meters) up in the air, and the receiver is very sensitive and compares well with bigger rigs. At a club meeting we listened to the rig indoors using a Miracle Whip and it still picked up plenty of strong signals, some as much as S9+20, despite the small, poor antenna inside a building. I had hoped the internal peak filter (model PF-1A) would help with selectivity, but it tends to ring and is far less helpful than I had expected. Even so, the rig can be quite pleasant to operate when compared with similar, monoband CW rigs. The radio draws only 75mA on receive, 280mA transmitting at 600mW out, so batteries should last a good long time. This rig is an excellent choice for backpacking or field operation.

I heartily recommend the P-7DX for the CW QRP enthusiast. The combination of small size, solid construction, and decent performance make this one a winner. It's a pity nobody every commercially imported these rigs into the U.S. If you aren't in Japan or don't have friends there these rigs are hard to find. If you do see one, grab it!
WB5OAU Rating: 5/5 Apr 22, 2003 20:32 Send this review to a friend
Fine single band QRP package!  Time owned: 0 to 3 months
The P-7DX is a wonderful self contained QRP superhet transceiver. This rig is smaller than it looks in the picture but feels and performs larger. The VFO as shipped from the factory, covers the bottom 30kHz of the 40m band. Dial tracking is quite accurate, and only about 1kc low at 7030, dead on at 7000. I had my doubts about how well this was going to work with only 600mW out, but with just a relatively low dipole (35' high) it's quite easy to make plenty of contacts. The VFO is stable and the RIT works well. This radio has the smallest speaker I've ever seen (about 1/8" thick) and comes with an internal 6 penlite battery holder. It's easy to get to the cells, as the top slides off when the thumbscrews are loosened (they dont need to come out all the way and get lost!). A 9V external DC supply may also be used, via a connector on the back panel.

This attention to detail is apparent throughout the radio. All the controls have a "big radio" feel, that is missing in lots of small single band QRP rigs.

While the radio is fine as is, a audio filter would help cut down some of the nighttime qrm on 40m, when the going gets rough. During daytime operation, the internal filtering is perfectly adaquate.

I own a few small single band QRP rigs, and this rig will be one of the one's I'll not part with.

My example was built in 1998. I would love to find the 15m version of this (please contact me if you have one for sale).

John K5MO

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