Building The Hard Rock 50
A 50 watt HF amplifier

Even before the kit arrived I proceeded to put together a "Construction Manual".
It contains all the needed Assembly Instructions for the Amplifier,The
QSK board. The Automatc Antenna Tunner (ATU) and Operating Instructions.


I did this so I couLd review the manuals and instruction sheets. The manual was printed
from PDF files downloaded from the Hobby PCB web site.
After printing they were placed in a spiral binder to allow easy
access and have been reviewed several times over the last couple of weeks.
Before ordering the HARD ROCK 50.

~ ~ ~ ~ ~

The first thing is to inventory the kit to be certain everything is here.

Notice I use an anti-static mat and wrist strap when working on the Amp
as ALL IC's and SMT components are pre installed on the PCB's.
In these pictures you can see the Front Panel, Rear Panel and the Main
Amplifier PCB. Also some of the preinstalled components.

Pictured here is the QSK PCB. I 'm just starting the inventory.
I don't wish to confuse things by opening too many bags

Look at the size of the heat sink. MAN!

The HARD ROCK 50 arrived on 19 AUG 2017

A couple of points here.
It has been several years for me since I've done a major project such as this.
Also I like to document my builds so this will go slowly. BTW It has Ser# 1827

The Hard Rock 50 assembly is organized into the fowing subassemblies:

Front Panel PCB

Back Panel PCB

Inductors and Transformers

Amplifier PCB


Final Assembly

Test and Alignment

It will be inventoried and built in that order
So not to mix the components each package will be inventoried when needed.

~ ~ ~ ~ ~

Now the Front Panel PCB

Front Panel PCB inventory complete.

On the front side of the Front Panel PCB

Step 1: Locate, install and solder trimpot R111.
Step 2: Locate, install Female Header JP102 and male Header JP101.
Insure that they are flush and trimed close when soldered

Step 3: Locate, and install the 1X16 pin Header

Step 4: Install the short side into the PCB and the long side up.

***Solder one pin to check for for square. DO NOT SOLDER THE REST OF THE PINS AT THIS POINT

Step 5: Using 4- 0.188" (4.8mm) nylon spacers, 4-4 1/2" (12.7mm)screws, 4-#4 lock washers 4-#4 nuts
Loosely tighten finger tight for now. DO NOT SOLDER THE LCD AT THIS TIME,

Step 6: Locate and install switches S101, S102 and S103.

*** Set the switches flush on the PCB. DO NOT SOLDER

Step 7: Locate and install bi-color LED D5
*** Note the flat side and align with silk screen markings.

Step 8; Align the front panel with the LCD, pushbutton switches and LED, If the fit is snug.
Loosen the LCD mounting screws to provide "wiggle" room

Step 9: Using 3-#4 0.375 (9.5mm) spacers, 3-3/4"(19.1mm) screws, 3-#4 lock washers and 3- #4 nuts.
Mount the panel assembly to the front panel.

*** The nylon spacers may need to be FLAT SIDED into a "D" shape to fit

Step 10: Tighten all 7 mounting screws so that they are snug

Step 11: Solder the pushbutton switches, LED and the remaining 15 leads of the LCD to the Front Panel PCB

Step 12: Remove the 3 sets of hardware holding the front panel in place

Step 13: Solder the 16 pins of the header to the LCD module and re-tighten the LCD module hardware.

Step 14: Reinstall the front panel with the 3 sets of hardware tighten.

~ ~ ~ ~ ~

Now the Back Panel PCB

On the front side of the Back Panel PCB

Step 1: Locate and install make sure that the header is flush.

On the Back side of the Back Panel PCB

Step 2: Skip step 2 if PCB rev "H" Step 3: Locate, install and solder the USB connector at X303

Step 4: Locate install and solder the RCA connector at X104 ( PTT_IN) location).

Step 5: Locate install DB9 accessory Jack at X302. DO NOT SOLDER

Step 6: Using three #4 5/8"(15.9mm) screws, 0.25"(6.4mm ) spacers and 4 #4 lock washers.
Attach the Rear Panel PCB to the rear Panel.

Step 7: Tighten all hardware and solder the DB 9 pins

~ ~ ~ ~ ~


23 AUG 2017__10:10AM

Inventory completed

I ordered the Prewound Torid_Kit So will be using them.

Even using the prewound toroid kit.

I need to make several checks on the SMT inductors L1- L4
Wind inductor L5, wind transformers T1, T2 and T3

23 Aug 2017 4:30 PM

Check for 50 ohm from the gate of Q1to center pin VR1___measured 50ohms
Check for 50 ohm from the gate of Q2to center pin VR2___measured 50ohms
Check for 50 ohm from the gate of Q3to center pin VR3___measured 50ohms
Check for 50 ohm from the gate of Q4to center pin VR4___measured 50ohms
Check center pin of VR1 to Ground___ measured greater than 1 Meg ohm
Check center pin of VR2 to Ground___ measured greater than 1 Meg ohm
Check center pin of VR3 to Ground___ measured greater than 1 Meg ohm
Check center pin of VR4 to Ground___ measured greater than 1 Meg ohm

Wound inductor L5

Two loops of #18 wire through a BN43-202 core

Wound transformer T1

Two turns of #22 teflon wire on BN43-202 core
one white wire and one blue wire

Wound transformer T2

Four turns #18 enameled wire on T73-43 core
wire scraped, trimmed then tinned

Wound transformer T3

10 turns of #30 kynar wire on each side of BN43-202 core
The kynar wire was replaced with 27ga enameled wire, trimmed then tinned.

24 Aug 2017 6:00PM

~ ~ ~ ~ ~

30 Aug 2017 7:30AM

Other projects became a priority for a while.
Have just managed to get restarted on the Hard Rock 50

~ ~ ~ ~ ~


Inventory complete


INSTALL a jumper at the QSK indicated spot

Step1: Locate and install (SOLDER) four brass standoffs on the back side of the AMPLIFIER PCB

Step2: Locate and install relays RLY2, RLY3, RLY4, RLY5, RLY6, RLY7, RLY8, RLY9, RLY10, RLY11,

Step 3:Locate and install 3 PIN Header at DRV location. Observe orientation tab.

Step 4: Locate and install 5mm 45 degree terminal block at 13VDC.

Step 5: Locate and install 1L Ohm trimpots at VR1, VR2, VR3, and VR4. Observe orientation on PCB.
Trim leads Turn each adjustment screw at least 25 turns CCW to ensure a bias voltage will be "0" volts

Step 6: If the QSK jumper is installed DO NOT INSTALL "RLY1"

Step 7: Locate and install 2 pin terminal blocks at RF_IN, RF_OUT, AMP-IN. OBSERVE ORIENTATION ON PCB
NOTE*** If installing the QSK board DO NOT install 2 pin terminal blocks at RF_IN, RF_OUT,
Get the the 3 pin and two 2 pin headers receptacles from the QSK parts kits and solder them at
QSK-A, QSK-B (2pin) and QSK-C (3pin).



Step 8: Install inductors L6 and L7, T50-6 core 5 turns #22 ga enameled wire
Install inductors L8 and L9, T50-6 core 8 turns #22 ga enameled wire
Install inductors L10 and L11, T50-6 core 9 turns #22 ga enameled wire
Install inductors L12 and L13, T50-2 core 12 turns #22 ga enameled wire
Install inductors L14, T50-2 core 17 turns #22 ga enameled wire
Install inductors L15 , T50-2 core 24 turns #22 ga enameled wire

Step 9:Locate and Install transformer T2.

Step 10: Locate and install inductor L5
Step 11: Locate and install transformer T1

L5 two turns black #18 ga wire.
T1 two turns blue #22 ga wire and two turns white #22ga wire

Step 12, 13 and 14: locate and install T3 the monster

T3 consists of 10 turns #27 ga enamal wire on both sides of a BN43-202 core
and one single turn of #22 ga wire through each side

Stopped Aug 30 5:35pm

Restarted Sep 06 2:00 pm

Step 15: Locate a the RG-316. Cut a 5" section and each end.

Step 16: If installing the QSK PCB set the coax jumper aside for later use
Skip to Section 13 the QSK PCB

~ ~ ~ ~ ~


Step 1: Locate and install four 1N4007 diodes at D401, D402, D403 and D404 on thr front side of the PCB.
Observe orientation

Step 2: Locate and install two SSN1N45BTA MOSFETS at Q401 and Q402 on the front side of the PCB
Observe orientation

Step 3: Locate and install two orange relays at RLY401 and RLY402 on the front side of the PCB
Must be mounted flush to the PCB.Observe orientation

Step 4: Locate and install 2 pin terminal blocks at RADIO and ANT locations. Observe orientation

Step 5: Locate and install two 2 pin headers at QSK-A and QSK-B Locate and install one 3 pin header at QSK-C

Step 6: Locate the RG-316 jumper prepared earlier. Insert the end prepared for the PCB in the RLY-OUT position


~ ~ ~ ~ ~


Stopped Sep 6 4:35pm

RESUMED 6:00AM 7 SEP2017

INVENTORIED the chassis pack

All items present or accounted for.

I'm using a little different procedure for the final assembly.

See the screw heads inside the PCB holes

A PAUSE 5:00 7 SEP 2017

RESUME 8:30 7 SEP 2017

Soldered the outer pin on each end of the outside row

Removed the front panel. See the dual row connector?

LM35 IS SITTING FLAT. Side view is a better look.

A PAUSE 10:45am 7 SEP 2017

RESUME 8:30pm 7 SEP 2017


The 47uh inductor L2 in the Q2 gate circuit
Was snicked when trimming the pins with flush cutters
The circuit is open I checked it with DMM.

Used Solder Wick to pick up the solder on L2
Then a scribe to pop L2 while reheating the L2
Then wicked up any remaining solder

(L) damaged L2, (C) L2 removed, (R) L2 replaced

A PAUSE 10:45pm 7 SEP 2017

RESUMING 9:00 14 SEP 2017

Heatsink compound allplied. AMP PCB remounted. see screw heads?

Power switch installed.

Front Panel installed and 20 pin connector alignment checked.

Power Pole connector installed on rear panel.

One 3" and one 6" going to install the ATU also.

6" coax on OUT 3" coax on IN

A PAUSE 4:15 pm 14 SEP 2017

RESUMED 7:30AM 15 SEP 2017

Installed QSK PCB

Hooked up the QSK PCB to the AMP PCB

Attached rear PCB. hooked up power cables

Connected QSK cables.


The actual AMPLIFIER construction is finished. Now what
remains is setting the Bias and check out in the
ALIGNMENT section.

I am waiting on a 47uh inductor replacement part to proceed.

~ ~ ~ ~ SO ~ ~ ~ ~

I jumped to the ATU build while waiting for the inductor.

Building The Hard Rock 50

~ ~ ~ ~ ~

The first thing is to inventory the kit to be certain everything is here.

The Hard Rock 50 ATU assembly is organized into the fowing subassemblies:


Inductors and Transformers

PCB Assembly

Amplifier Prep (only needed on older Amp)

Integration and final assembly

~ ~ ~ ~ ~

Now Inventory

Inventory complete.

IC's and SMT's are factory installed

~ ~ ~ ~ ~

I ordered the Prewound Torid_Kit So will be using them.

~ ~ ~ ~ ~


Carefull inspect the ATU PCB looking for poor soldering on the SMT components.
Look for unsoldered ferrite beads; they seem to be prone to re-flow issues


D/N/A The IC U1 and it's socket were replaced with SMT components

D/N/A The IC's U2 and U3 were replaced with SMT components

Relays RLY1 Thru RLY 17 installed

Installed toroidal inductors L1, LA, LB, LC, LD, LE, LF and LG

D/N/A Bottom of case is predrilled

D/N/A Bottom of case is predrilled

A 47uh inductor replacement has been received
and installed now I am able to bias the AMP

The next step is INTEGRATION after
the inductor is installed and AMP is aligned.

Mon 18 Sep 2017 Inductor has arrived and been installed

Now on to the Alignment procedure

Test 1: Set the DMM to read resistance. With power switch in the 'OFF' position.
Place the positive meter lead on the red powerpole contact and the negative lead
on ground. The reading may change as capacitors in the circuit charge but the final
resistance shoud be in excess of 100K ohms and may read of the scale on some DMMs

***reading was 431 ohms

Test 2:Place the power switch in the 'ON' position make the resistance measurement.
You should now see a resistance of at least 1.5K ohms. With QSK board installed you
should greater than 350 ohms.

*** reading was 0.L m

Test 3:Keep the negative lead on ground and measure the resistance of each of the
MOSFETS (Q1-Q4) gate pins (the gate pin is marked with a 'G' on the silkscreen). Each
of these should measure between 40 and 60 ohms. If the reading is higher than40-60
double check that VR1-VR4 are fully CCW

*** readings___ Q1_gate 56.6 ohms, Q2_gate 52.2 ohms, Q3_gate 53.1 ohms, Q4_gate 56.8 ohms

From Test1: and Test 2 results assume on/off swich backwards.

corrected switch wiring retested results were as desired.

Test 1:*** reading was 0.L m,p>
Test 2: ***reading was 431 ohms

It is now safe to apply power to the amplifier. When power is applied, the front panel LCD will display a row of
filled rectangles for a few seconds, followed by the firmware identifcation screen for 3 seconds then enter the
stand-by screen whick displays the keying mode, Band , Temperature and DC input voltage. If the display is
blank or difficult to read, adjust the contrast control, R111, on the control PCB

Step 1: power applied and checked 13.51VDC

step1: DCV set 13.51vdc
checked at DC POWER BLOCK 13.51VDC
display blank. LED blank. nothing clicks bleeps or bloops.

~ ~ ~ ~ ~   EMAILS   19 SEP 2017 ~ ~ ~ ~ ~  
to jim Veatch  step1: DCV set 13.51vdc
checked at DC POWER BLOCK 13.51VDC
display blank. LED blank. nothing clicks beeps or bloops.
Jim Veatch 12:14 PM (5 hours ago)
to me
Check the voltage test points on the control board.
Robert 'RC' Conley 
12:59 PM (5 hours ago)
to Jim
control board +5v  test point shows '0' vdc
control board +13.8 test point shows '13.44 vdc

Jim Veatch  2:23 PM (3 hours ago)
to me
Hmm. Well that indicated either a bad regulator, which was tested before it was sent to you;
could be something up with the display but I'm going to bet a ribbon cable issue. 
Completely remove the ribbon cable then see if the 5V comes up.
Robert 'RC' Conley 
2:38 PM (3 hours ago)
to Jim
Ribbon cable removed
rechecked control board
tests remain unchanged
Jim Veatch 4:43 PM (1 hour ago)
to me
What is the resistance from the 5V test point on the control board to ground with the power off?
Robert 'RC' Conley 
5:15 PM (48 minutes ago)
to Jim
Cen-Tech DMM meter #1 shows 0.5 ohms to gnd on chassis and control PCB gnd...
.. meter #1 lead resistance is also 0.5 ohms

Radio Shack AUTO-RANGE DMM meter #2 shows 3.5 ohms to gnd on chassis and control PCB gnd....
...meter #2 lead resistance is also 3.5 ohms
Jim Veatch 6:19 PM (14 minutes ago)
to me
I'm confused are you measuring from basically 0 ohms from the 5V test point and the control board to ground? 
If so there's a short and it's most likely in the 10 pin connector or the LCD connector.

We programed the microprocessor with the firmware before we shipped you the amp kit. 
If there were a short between 5V on ground somewhere on the PCB itself, the programmed 
would have failed and the board would have been rejected.

If you can't find the short, you may need to send me the amp.

Robert 'RC' Conley 
6:32 PM (1 minute ago)
to Jim
Jim I measured from the 5V test point on the control PCB to the ground point on the PCB 
and from the 5V test point to a chassis ground and measured the test lead resistance on 
two different meters  a Cen-tech DMM from Harbor Freight and my old trusty Radio Shack 
Auto-Ranging DMM..

Jim I have no problem boxing both the AMP and ATU to you via USPS PRIOITY MAIL. 
As it stands now I'm just about out of my element.

~ ~ ~ ~ ~    EMAILS   23 SEP 2017 ~ ~ ~ ~ ~  
Hi RC,

Your amp arrived here today thank you for paying for the return postage. I've had it up on the bench for the last few hours. 
The short on the 5V line was caused by solder bridges on the header that connects the LCD to the control board one of 
which was on the backlight pins shorting 5V to ground.

The power switch was melted pretty badly and had 'mushy' action as well as being unreliable so I replaced it.
 They melt very easily, I'm always replacing them.

I brought it up and it had no output on 160 or 80M which I traced to one of the relays installed backwards. 
That has been corrected and now the amp makes 50+ watts 160 to 10M with 2-3W drive and over 40W on 6M
 with 5W drive just like it should.

A routine inspection of the ATU revealed several unsoldered pins which I took care of and I'm ready to install 
and test the ATU. I hope to have it done tomorrow and in the mail on Monday possibly Tuesday if tomorrow is really busy.

Robert 'RC' Conley 
8:41 PM 
to Jim
It is only right that I provide the return postage. I'd also like to  pay you for the time you spent on it.
It looks like I'm going to have to stop building if I missed all of that. I've enjoyed building so very 
much through a dozen Elecraft transceivers over the last 10+ years. Even some for the local guys. 

Your Hard Rock 50 ought to make my 5 watt KX2 and a wire sound  BIG.
Thank you Jim letting me know what I did wrong.
Jim Veatch
~ ~ ~ ~ ~  EMAILS   24 SEP 2017 ~ ~ ~ ~ ~ 	
2:00 PM 

Hi Robert,

There's a lot to building a HR50 to keep you on your toes. I'd say that overall you did a pretty good job, 
use less solder and a little more time to heat the pads so it flows thoroughly. The ATU came up dead and 
I that traced to reversed red and yellow wires on the power cable. I wish I had checked for this before 
I powered it up because I put 12V on one of the microprocessor leads and it's protection diode dumped 
12V on the 5V line which pretty much took out every active component in the tuner, and even if there's 
a part that isn't bad there's a good chance it'll fail early. I guess I should add a series resistor to eliminate 
that as a potential problem.

But we are in luck since we recently made a design change to the ATU and I built a pair of prototype 
units to verify that the new design was OK. So if you open the case you'll see that the ATU board is 
green rather than blue but it's a 100% operating and tested build by yours truly.

Your amp is now working 100% and setup for automatic band switching with the KX2/KX3 series radio. 
ATU tunes 5-500 ohms 80-10M with a bit less range on 160 and 6 which is perfectly normal.

We do not charge anything to get amps up and running. 
A working amp/atu is included with the purchase price.

Looks like it'll be there on Wednesday.


After having been returned I wanted to see inside.

Opened out. you can see the front panel (L), The Amp(T), The ATU(B), The Rear panel(R).

A better view of the AMP PCB (L). Also the ATU PCB(R).

A better view of the Front Panel PCB (L). Also the Rear Panel PCB(R).