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Reviews For: Hi-Res Communications PDC-1 Peak Reading add-on

Category: SWR & Wattmeters & Dummy Loads

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Review Summary For : Hi-Res Communications PDC-1 Peak Reading add-on
Reviews: 9MSRP: 24.95
Circuit Kit for adding peak-reading functionality to average reading wattmeters
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
AJ8MH Rating: 2022-04-14
Added to MFJ-998 Time Owned: more than 12 months.
I've just received my third PDC-1 and have completed installing it in my MFJ-998 1.5 KW Auto-Tuner. PDC-1 works as expected without modification. The price is reasonable and the shipping was fast. Details can be seen on my web site. (Search by my callsign.)

Site also covers installation of the PDC-1 in the MFJ-949E and the MFJ-962D Tuners.

I just removed my first PDC-1 from my MFJ-949E and installed it in my new MFJ-993B. Works great and it will be added to my operating position at the cabin.
W6MTF Rating: 2018-05-26
not a heathkit Time Owned: 0 to 3 months.
Good thing I checked each component before installing as I discovered that the resistor included for R1 was 68K OHms, not 680 Ohms (I still know the color code!).
Second issue was the trim pot R4 for decay time included with the kit has access to the adjustment screw completely obscured by the IC. I had to order one from DigiKey with the proper lead configuration (Nidec p/n CT6EP-105). I also wanted the cal pot R2 to be similar so I ordered one also (CT6EP-501).
I saw right away that there is no mounting provisions for this board. It would be nice if a couple of holes were provided along one edge of the board for small standoffs or screws to support it!
Overall this kit was more of an aggravation than I expected.
When I hadn't received the kit my email to W8RO seemed to go into a black hole so Pay Pal to the rescue! Only then he got back to me and informed me they were out of parts but would be shipping soon. The order form specifically asks for an email but I guess it isn't used to inform buyers of delays.
I would rate this as less than a professional product, the documentation is great but there are similar kits for a little more $ than this that are light years better.
K0CWO Rating: 2017-01-20
Excellent value Time Owned: 0 to 3 months.
I built the kit and installed it in an MFJ-998 tuner in about 2 hours. Installation, calibration, and decay time are a breeze to adjust in this tuner. No component value changes required, This addition makes the MFJ-998 as it should be. Highly recommended.
NS1Z Rating: 2008-05-03
Big bang for the buck! Time Owned: 0 to 3 months.
Ordered over the 'net and arrived promptly. Instructions were clear and complete. All parts included (as well as the Bird 43 components!) and correct. Put together quickly in under 90 minutes. Worked first time powered up. Calibration was quick and easy. Very simple kit with great feature addition to my Model 43 Bird wattmeter. Good Job!
K5WLR Rating: 2004-12-24
Kit building again (sigh) Time Owned: 0 to 3 months.
I miss Heathkit.... However, I had a bit of deja vu this week. I put together and installed a Hi-Res PDC-1 Peak reading kit in my Bird 43 wattmeter. After I obtained the resistors required to use it with a Bird 43, the kit went together quickly and the adjustments were simple and accurate. Works like a champ! Now for the woodpecker kit....
K6AER Rating: 2004-06-18
Drake W4 with PDC-1 Time Owned: more than 12 months.
I installed the PDC-1 peak reading module on my old Drake W4 watt meter. The watt meter is about 8%accurate from 10 to 2000 watts in forward and reflected modes. The kit took about 40 minutes to build and another 30 minutes to install the RMS/Peak switch. Accuracy in the peak mode is about 10% as measured on my 8953E spectrum analyzer in peak mode. This is well within ham grade instrumentation. I would highly recommend this kit for any well built watt meter.

Earlier 5-star review posted by K6AER on 2004-06-17

I added the Hi-Res peak reading circuit to my Drake W-4 wattmeter. This watt meter has an accuracy of about 8%. The circuit was straight forward and took about 30 minuets to build. I checked the watt meter with my HP8953E spectrum analyzer in the peak reading mode and found the watt meter to be within 10& accuracy in both the forward 200 and 2000 watt scale and the reverse 200 and 2000 scale. I have since bought a Alpha 4510 digital HF watt meter but miss the little Drake unit.
NN8E Rating: 2004-04-02
Docs have been revised, Good Buy! Time Owned: 6 to 12 months.
The folks at Hi-Res have revised their docs regarding usage with the Bird 43 and now show the correct resistor values.

It's hard to justify spending the BIG BUCKS for the Bird add on when this one works just fine!



Earlier 4-star review posted by NN8E on 2003-06-17

I read the reviews here and purchased the kit for use in a Bird 43. I built it and tested it extensively and confirmed the exact errors in the documentation. I met with Floyd Soo and Chuck Hawley, both of HiRes, (Chuck is the design engineer) at the Dayton Hamfest this year regarding errors in the documentation and they acknowledged and understood them. I’ll detail the results in the next paragraphs. Overall, I am still satisfied with the operation of the kit and believe it to be a good value at $24.95. I hope Floyd and Chuck correct the errors.

The kit, as it comes contains parts to configure it for use with the Collins 312-B4,5 wattmeter(s). The key difference between the Collins and the Bird are the full scale current and dc resistance of the meter movement.
Collins=200uA, 1000 ohm
Bird=30uA, 1400 ohm (I own 4 Bird 43’s and all 4 meters are approximately 1400 ohms)

The values of 3 resistors should be changed to use this kit with a 43. R1 must be increased to a value of 1K or 1.2K. This is correctly stated in the documentation! The value of R7 should be changed to 1M. This gives the circuit more dynamic range. This could be any of a wide range of values, but 1M is just fine. This is also correctly stated in the documentation!

What’s incorrect in the documentation is the required value of R8. It is stated that 51K should be used. This is WRONG. It results in a full-scale reading of 41.2uA (when using 1M for R7). I calculated this value from the simple formula and also measured the same during testing. (I don’t know where NX7U got his value of >50 and attempts to contact him failed. He wrote one of the other reviews of this kit)

The correct value for R8 is calculated to be 70.55K. I used a decade box during testing to verify operation using this value and the circuit produced exactly 30uA, as intended. The closest standard value is 68K (keep in mind a 5% resistor can range from 64.6K to 71.4K !!!) You can also add a small value in series to get you closer to 70.55K if your actual value is too low. Finally, the input pot, R2 can be adjusted slightly to produce exactly 30uA output when a known full scale signal is run through the 43!

I agree with NX7U regarding the clarity of the ‘how it works’ section of the documentation. It's easily understood. This is a simple op-amp circuit and the analysis I performed is not complicated, and easily duplicated. If anyone has any questions, I’d be happy to respond. Thanks to Floyd and Chuck for acknowledging their errors! Give it a try!
WJ5MH Rating: 2001-09-16
Good Buy Time Owned: 0 to 3 months.
I have installed two PDC-1 adapters during the past 30 days, and both are working as advertised. I can recommend these without hesitation.

My notes on installing the PDC-1 PEAK Reading Adapter in the MFJ-949E and MFJ-962D tuners can be found at:
[ ]

NX7U Rating: 2000-07-18
Inexpensive kit, but docs off Time Owned: 0 to 3 months.
Installed recently in my Bird 43. Kit is just a small (1-1/2"x1") double-sided PCB with an op amp and a few add'l components. You supply DPDT switch, 9V battery, and interconnect to the wattmeter proper. FWIW I used a 6-pin 0.062" molex connector and mounted the board using hex standoffs to the back plate of the '43, that way I can disconnect it completely w/o undoing anything.
The kit works quite well, with adjustable decay time constant and a somewhat rudimentary method of calibrating peak-vs-average to match up. The only complaint I have is that the accompanying documentation contained specific instructions on modifications to use it with the '43. So (1) gotta get some different resistors (not supplied, trip to the parts store) and (2) turns out that one value is miscalculated...not a good miscalculation because it results in a full-scale deflection of >50uA (on a 30uA meter). Pound the Pin!! So after some pencil figuring (fortunately the documentation contains a fairly complete "how it works" summary) I changed one value and it's spot-on now.
All things considered, it's a steal at $19.95 (compared to the peak reading kit from Bird which I think is >$100), but surely I'm not the first one to notice this doc error...glad I didn't bend my meter needle or burn out the movement!