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Signal/One CX7A Restoration
Chassis Number 00025
How it got started

Since I have two Signal One CX7s I thought it would be a good idea to gather up some more spare parts. I intend to keep these transceivers on the air as long as I'm taking in air. I have a rather large collection of parts that I acquired during the 70s and early 80s. Now it's the 21st Century and you gotta luv good ole ebay. Chuck, N6FX, listed a "junker" CX7 with modules, case and the power transformer. Why not? Great way to add to the parts bin.

When the three boxes arrived I was very surprised. There was a complete set of modules and some extras. All the knobs and even a brand new front panel were included. The poor radio had been gutted. I will detail the extent of the destruction on other pages of this section. BUT, with the exception of a few minor and one not so minor parts this was a COMPLETE Signal One. The case and front panel are in great condition. I could not bear the thought of finishing off a CX7. Yes, I know, they are quirky radios but there is such a history behind them. Not to mention the link to the legendary Alpha Amplifier line. Paul Koller though that perhaps half of all CX7s built are still in existence. That would put the number at about 425. I hope Paul was right but from what I can find that number is a lot smaller.

So much for spare parts. I decided to rebuild this radio. One thing I found in my Signal One documents is the factory Final Checkout Procedure. 35 pages! Since I will essentially be "building" a CX7 this procedure is going to be invaluable.

Meanwhile, back at the ranch, another batch of CX7 parts shows up on ebay listed by a ham in British Columbia. OK, now I gotta have these as well.

This radio has number 00025 on the rear chassis panel . The serial number information I have indicates the Florida radios started at 00100 so this must have been an internal control number. Otherwise, starting serial numbers at 00100 is an error. The chassis has 00025 in black numbers in the area that would have been covered by the rear label. This radio must never have had a serial number label on it since #025 is written on the original manual in Bob Dunten's handwriting and there is no evidence of a label having ever been on the radio.

In early 1970 a ham in Corpus Christi, Bob Dunten (SK), bought a CX7 from Douglas Electronics. After several years Bob finally decided this radio wasn't worth the trouble it was to keep it on the air. Ric Hoffman, K5SBU paid him $125 for the rig. Ric and I have been friends since the early 70s. During a move from Alpine, Texas back to Corpus Christi the dumb-ass movers put a box of powered soap above one of Ric's Signal Ones. Of course the soap came open and went inside the radio. Ric sent both of these radios to Paul Koller who, after much discussion with Ric, decided to repair his S/N 00125 using parts from C/N 00025. Paul was to keep 00025 to use for spare parts. After Paul passed away, Chuck, N6FX, acquired some of his spare parts. As mentioned above, I bought Chuck's remaining spare parts in 2005 on ebay. What "clicked" and made me realize what radio I had was when Ric gave me several Signal One manuals. One of these was the original manual Bob got with his CX7 and on the cover, in Bob's handwriting, is "Bob Dunten #025".

So, this radio went from Bob to Ric to Paul to Chuck and finally to me - right back in Corpus Christi. I'm very glad to have this radio back on the air even if many of the modules are not original. Actually, as early as this radio is, it's probably good that many of the prototype boards are NOT in it.