Norcal 40A 30A..that's "30" for tonight.. (Update)

Posting WB6JDH's 30 meter mods for the 40A. These are more comprehensive than W0CH's mods and will be the ones we pursue on our builds. Stay tuned.

30 Meter Mods Per WB6JDH
(1) Install 8 MHz crystals for X1-X6.
(2) Matched X1-X4.
(3) T1 is wound as follows:
   Pri 13T
   Sec 3T
(4) T2 is wound as follows:
   Pri 2T
   Sec 17T
(5) T3 is wound as follows:
   Pri 18T
   Sec 4T
(6) C6 is 22 pF NPO
(7) C9-C13 are 470 monos or 470 C0G or 470 NP0 if they fit
(8) C14 is 47 pF NP0
(9) C35 is around 151 pF (see notes below)
(10) C38 is 68 pF NP0
(11) C52 and C53 are 1500 Poly
(12) L4 is 10 uH
(13) L5 is 15 uH
(14) L6 is 24T
(15) L9 is 62T
(16) RFC1 = 15 uH
(17) R12 is 18-22 Ohms
(18) AGC Mute Circuit
   R4 is 4.7 MOhm
   R8 can be jumpered

Sanity Check Test Measurements
(1) U2 measurement:
   Pin 6 = 0.80 Vpp
(2) U4 measurements (on transmit):
   Pin 4 = 0.15 Vpp
   Pin 6 = 0.30 Vpp
(3) Q5 Measurements (on transmit):
  Source = 1.0 Vpp
(4) Q7 Measurements (on transmit):
   Base 2.5 Vpp
(5) Q8 Measurements:
   Source = 3.4 Vpp
   R23 on C7 side = 0.8 Vpp
   Rxvfo label = 0.8 Vpp

Regarding the oscillator circuit for U4, Dick was concerned because the drive to the base of Q7, the final transistor, was too low at 2.5 Vpp. At first, he thought it might be due to the crystal activity of X6 hanging off of pin 6. However, fishing through his stack of 8 MHz crystals and finding a substitution with more poop did not alter the drive that much.

Instead he proposed dropping the value of C35 hanging off of U4 pin 7 with something a little less than the 270 pF original. Dick tried a 150 pF NPO cap and reports that the power output for his 30m version was raised to just a shade under two watts. Recommend you try a temporary insertion until an optimum value is found. But be careful, however, as too low a value will swamp U4's oscillator.

Important Building Caveat
Q6 is the 2N222A driver and it requires a ferrite bead on the base. This is specified in the original NorCal 40A assembly manual as:

 FERRITE BEAD, 0.146" O.D., 0.138" long #64 material

The original assembly instructions tell you to "[after installing the ferrite bead on the base] push Q6 down onto the PC board so that its leads are as short as possible". Follow these instructions but be sure that the bead DOES NOT TOUCH the other two leads of Q6 or you will be in a world of hurt.

When I was doing the final tests on this, a mysterious 2.80 VDC voltage showed up on the collector of Q4 (the 8V TX keying circuit) and in the part of the circuit involving U4 (the transmit mixer) and Q5 (the buffer). This voltage turned on transmit and resulted in two tones (signal generator input and transmit side tone) and other general havoc. After trying to isolate Q4 from any other external influences like removing it (Q4), U4, and Q5, C29, and C30, the mysterious voltage still persisted.

Finally, I surmised that it must be Q6 and it was wicked out causing the voltage to disappear. After Q6 was correctly reinstalled with the ferrite bead insulated from the other two leads and all of the removed components were replaced things more or less returned to normal. Seems that some ferrite beads are made of materials that are conductive and caused a voltage to appear on the base of Q6 that leaked back into the transmit mixer circuit and played the hell described above.

..oh! And this note: Joe, W2KJ, sent me a PM and said correctly pointed out that the TO-18 (metal can) 2N2222A has a different pinout than the PN2222A. The former (looking at it with the metal tab on the left) is EBC left-to- right while the TO-92 PN2222A (looking at the flat side) is CBE left to right. But hey, PNP BJTs are kinda the same as MPF 109s or J310s, right?

Bottom line, I replaced Q6 with a PN2222A in lieu of the TO-18 2N2222A and that seems to work fine.

Beginning the Norcal 40A 30A

..historical post rescured from my old Right Hand of Zod Blog. Ignore the conteroraneous errors and enjoy!

O.K., this is really it! I am starting the NorCal 40A build -- except that I am building it for 30 meters since I already have a 40A in hand that I scored at TRW from a seller for a decent price. I tuned that one up and adjusted its output to 995 milliwatts so it could rightly work QRPp. Quite a few Qs for the few times it was used, actually. One of my faves was the Maritime Station at Bolinas Beach, KPH. The ham station 700 miles from my QTH, K6KPH, was worked twice and represented an exhilarating accomplishment for me.

Since then, I ordered a NorCal 40A from Bob Dyer at Wilderness Radio before he retired. That kit still awaits the soldering iron. But, in addition to the 40A kit and the KPC1 keyer and frequency enunciator unit, I ordered an additional labeled blue face plate for the original 40A as shown above.

Some time later, in conjunction with K7QO's QRP-Tech 25th Anniversary GOTA project, I ordered the boards from China and am, as we speak, beginning the 30m effort in order to document WB6JDH's effort. A couple of months ago, I had gone up to Dick's house to do some preliminary recon work..

..but had not dug into the project until now. Starting out without anyone looking over my shoulder, I had to take the bull by the tail, as it were, and look the problem squarely in the face. At first, I was going to build and test sections at a time but, after reviewing K7QO's videos on this, I decided to proceed with stuffing the "generic" (i.e., non-band-determining) parts and then do Chuck's basic tests before Dick and I got together to make notes on just how to get the radio on 30 meters.

When that is done, it will be written up here and constitute a rough tutorial on how to build the 30 meter version for anyone who has built a 40A before. So stay tuned.

Along the way, some discoveries and assumptions have been made. Basically:

• Wayne Burdick or Bob Dyer apparently had a barrel of 0.047 disk caps that he used liberally throughout the kit. Standard 0.1 caps can be used in lieu of these.
• Q1 is specified as a 2N4124 NPN transistor but, according to Jim Kortge, K8IQY, a 2N3904 is an acceptable substitute. (Note that a 2N2222 is not acceptable.)
• An MVAM 108 is an acceptable substitute for the called for MVAM 109.

Further bulletins as warranted.

At first, I thought about laying out all the parts on a Styrofoam board to inventory them. But since the project was behind the power curve, I just stuck them into the board figuring that was as good a way as any to see what went where and what was needed. Guess the results can be rightfully described as "the porcupine".

Here's a few shots of the work to date.

UPDATE: See the picture below.