Thursday, December 30, 2010

NorCal S9 Signal Gen

NorCal S9 Signal Generator became available for a short while and I ordered on a few weeks ago.  It went together in a couple of hours and worked right away except for a few solder joints on the Xtals that needed to be redone.  If doing this again I would clean the leads on the Xtals and make sure the plated through holes are really plated through, as the connections to the circuit are on the top of the board.  The test oscillator reads right at S 8.5 or so (with a low battery) on all four frequencies on the FT-1000 Mk V.  Later I plan to do some measurements on the 3 DC receivers that I have here, using the MFJ attenuator that I purchased used to go with the test oscillator.

NorCal S9 Test Oscillator

Tuesday, December 21, 2010

Fisher 500 B

Fisher 500 B

This is a Fisher 500 B that my dad bought used out of the Washington Post classifieds in 1978.  I went with him to pick it up along with a pair of AR2a speakers and a Garrard Type 'A' Turntable.  He had it serviced at Audio Associates at Tyson's Corner and I have used it once in a while.  It still sounds great!  The On/Off switch failed when I tried it this year so I installed a 'jumper' and now it is on when plugged in.  About ten years ago these sold for $75 or so but now I have seen them for much recently after a good review in Stereophile magazine.  This review is actually for a 'C' but they are similar.  Some seem to prefer the earlier and simpler 400 models.

From the Stereophile Review

"A Fisher 500-C sold for $369 in 1964. That seems like chump change today, but in 1964, $2368 bought you a brand spanking new Ford Mustang (the 1964 New York Auto Show was the pony car's debut). Collector-condition Mustangs now trade for between $10,000 and $15,000. A mint, low-hours 500-C rarely goes for more than $600.
Where do you find a 500-C? Well, if it weren't for the Internet or a national marketplace (Pierre Omidar's eBay), these trusty old soldiers would be gathering yet more layers of dust in grandma's attic or the neighborhood thrift shop. But they're plentiful and shamefully affordable. Current market prices of functional 500-Cs run from $175 to $600. The top of the range is reserved for cosmetically mint and electronically restored units. But you'll be buying blind and deaf, so caveat emptor."

Palomar R-X Noise Bridge

Another Ham was looking for one of these.  I have had several and they work well for tuning antennas. Usually I have used them to tune mobile HF whips because you can hear the null in the Receiver.  They are often available and it can be a useful piece of test gear.

Friday, December 17, 2010

Bell 2122 Classic 6V6 Tube Amp

Bell 2122 Working Again!

When I was in 4th grade I listened to this amp playing classical hi-fi from a FM Tuner in Chatham NJ.  Years later I took it to college with me as a freshman.  The next year I upgraded to real stereo. The Bell worked until a few years ago when the power supply had the dreaded 'Hummmmm....' of a bad filter capacitor.  A quick Internet search led me to a post by someone else who had one and I acquired a nice copy of a 1948 Sams Photofax for the unit.  This year an internet search led me to Ampmonster, an Austin TX guitar amp company that had a good write up on restoration of the Bell.  With this site and the photofax I made a list of parts needed to redo the amp but when I opened it  up yesterday I tested the caps and found many of them to test close to value the electrolytics were bad though.  I took a 220uf and clip leaded it in parallel with the HV filter and the hum went away and the 2watt resistor connecting the two filter sections opened with some sparks and a small amount of escaping smoke.  An old replacement resistor was found and seemed to run cool so I wired the cap in for a more permanent temporary fix which will allow me to play with the amp a bit if desired.  Some DeOXit sprayed into the controls seemed to help and the tubes were tested and one bad 6SC7 (dual triode similar to the 12AX7 in a metal octal package) tube was replaced.

New Filter Cap in place

Sticker inside bottom plate

Rear panel

Pair of 6V6's