Many Accessories were made and sold with the Swan and Siltronix labels. Here are some of those "goodies" we have seen with Siltronix labels. If you have something to add, snap a picture and send it in. If you want to remain unknown, just ask us not to list your as source credit. There were some Swan and Siltronix products which are the same circuit, just different cosmetics. Have a look at the below pics and check back soon. We'll be adding many more as they come in.
The much sought after FD-1011 frequecy display only required AC line power and one cable to the radio. Actual frequency counter operation provided only a relative indication of the "window frequency." Mode offsets for SSB and AM were not provided. Over time, the operator learned the relative position of the operating frequency window vs the actual display value. Not the best, but it worked well and was real cool looking. The Red LED display segments often burned out with time. They can be replaced by most good techs in the know. One other display model(I have one) also included a CB Channel number display window along side the frequency display, driven by internal proms across the bcd lines. Quite a novel circuit... The 25.500MHz display appeared if you didn't have the unit plugged in and reading a radio vfo.
This is what it looked like inside. Just a batch of common TTL type dip chips, generating lots of 5vdc heat. The time base of this counter was specific to the Swan/Siltronix rig frequency generation schemes. It probably wont work on many other brand radios. The PC board is a well made glass epoxy type.
The counter rear panel, dc operation was possible. I believe the Siltronix Radio would run on one of the Swan DC Supplies, but I never bothered with such a big monster in in my small car. The transceiver cost way to much to leave overnight in a used 66 Chevy Impala.
The much prized SP-1011 speaker... Tech types liked to build projects, amplfiers and power supplies inside this External Speaker Box. The speaker didn't sound that hot unless you put some type of baffle behind the speaker. Both sides of the speaker cone are exposed and very easy to hear at the same time... lots of acoustic canceling and low fidelity audio happened without a pillow/baffel block in place. As supplied the speaker served more for show than real listening function. Watch them quickly sell to collectors for the big bucks on Ebay.
The very un impressive Sure 444 mic supplied with a dynamic low Z cartrige and the Siltronix name on the front. Sell it, keep it for show but don't use it. The Siltronix has a high Z input impedance and just loves a non-powered Astatic Brand, D-104 Mic (with the crystal cart mic head). It'll sound so much better vs the 444 and people will actually hear you. I built up a powered D-104 with a small limiter circuit which brings up my average level of modulation. A Major difference when the limiting is not over done. Enough audio is great... too much audio compression/limiting is trouble. I never understood why so many people missed the boat and used low Z dynamic mics on this rig.
Just below you see a picture of the Siltronix LA-550 mono band amplifier, a dual
stage sweep tube (8950's) type similar to the higher drive LA-600, LA 660 and
Swan 1200x "multi-band" Amateur versions. They are all classic TV Sweep Tube
Amplifiers using tubes like the 8950 or 6LQ6/6JE6 labels. The LA-600 and Swan
1200 were the ham tranceiver drive level versions for higher output exciters.
The LA-550 was a low drive unit (4 watts in, mono band "for use with a converted
cb on 10 Meters"),it has a low and high power setting, one grid driven 8950 stage
and four 8950 tubes in grounded grid final operation.
Current year 2001 Amplifier Technology has produced many traditional circuit modifications which can improve overall RF Amplifier stability/preformance. They are not always required for every and all circuits but they're well worth checking into. You don't want to buy any quanity of NOS tubes before you have too, so be careful using your sweep tube amplifiers. Go back to the Sonic Server Amateur Radio Page and look at my Dentron GLA-1000 Cathode Current Cut-Off Mod for typical amplifier upgrade information if your a technical type. Some of the most current amplifier update ideas and thoughts are layed out and presented in the article text. Sweep tube design is an amplifier science unto itself... please be careful.
Last Update: 04/28/04