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Why we won't just "upgrade" *your* Siltronix VFO

nomadradio

Analog Retentive
Apr 3, 2005
6,935
11,055
698
Louisville, KY
www.nomadradio.com
A question I get asked a lot is "How much for you to modify my Siltronix VFO?"

I reply that we don't do it that way.

The reason?

Simple.

Risk.

A 45 year-old VFO is like a box of chocolates. You never know what you're going to get.

This one was from a batch I bought at the Dayton Hamvention. Most of them were perfectly rebuildable. Didn't think I could very well sell this one. How reliable it would be to "modify" and send back to a customer? Doesn't matter.

U4yGEr.jpg



This one got dropped onto its face. The big tuning knob took the impact, and this reduction gear is the one just behind the big knob. The mounting ear on each side has been pushed back, and the reduction mechanism was totaly wockerjawed. Lotsa side play after this happened. Good thing I had a good reduction-gear mech from the rusty unit to fix this one.

vy0WMW.jpg


The Siltronix VFOs were famous for drift problems. I suspect that's what this guy was trying to improve with the masking tape, hot glue and hot wax dripped all over the inside.

BgAg1Q.jpg


I suspect that the white wax is in fact proper candle wax, and not just canning paraffin from the grocery store. The black pit marks and corrosion visible suggest to me that the wax has a high content of stearic acid. It serves to make the candle more rigid. Not so good for plated steel, though.

HFKcpQ.jpg


Changing the frequency coverage is a popular modification. These VFOs were built to match the many different crystal frequencies used in 23-channel radios. Murphy says that if you don't know which "number" version is right for your radio, you will end up buying the wrong one. This mod is pretty extravagant. Can't imagine it was terribly stable.

UMdqQc.jpg


The output level from the Siltronix VFOs is famously anemic. And the band selector on the model 90 will cause the output level from the "HF" band to drop to half or less what it delivers from the "CB" band. Output-buffer circuits are popular, too.

This one just didn't work.

l0TgUS.jpg


I'm sure this guy's intentions were good, but we all know which road is paved with those.

This buffer should have never worked, but qualifies as abstract art, I think.

JiGjU1.jpg


In all fairness, only some of these that we buy are too screwed up to modify and "digitize" and work like they should afterwards. A few of this batch were clean enough to eat off of inside.

But only a few.

About that "risk" thing. Here's the worst case:

Someone ships me a VFO and it is damaged before it's packed, or gets beat up in shipping, he paid for about ten pounds of freight (postage) to send it. I'll charge for the time to unpack, diagnose, estimate and pack it back up when the customer hears the price we quote for the job (and says "no thanks"). Add to that the shipping cost for the return trip, and we're darn close to 80 or 90 bucks, unless he ships it from somewhere VERY close by.

That just seems like a lot of money for bad news alone.

Don't need the grief, so we just invite them to buy one, and consider his used VFO for trade-in value.

Much less risk of an unhappy customer. And that's the risk I work hardest to avoid.

73
 

The cabinet paint on these is famously poor. Got some static from Ebay tire-kickers about how nasty some of them looked. Yeah, I'm a geek. How it works is what impresses me. But how it looks has more influence on how it sells.

Decided to start painting the nastier specimens. Found some decent-quality Rust-Oleum that puts a texture on the finish. Seems to hide defects in the old paint surface.

But this one had a spot that just flaked off. The original finish just came away from a clean spot in the steel surface and took my new finish with it in that spot.

Bummer. Thought I'd be clever and just use paint stripper to remove the rest of the original "wrinkle" finish and paint the bare metal.

You could see some rust at one edge of the bare spot that had flaked away.

First application of the stripper looked promising.

17OTjk.jpg


Didn't remove as much as I expected, so I applied another layer of stripper. The first layer exposed a lot more rust than I would have expected to find UNDERNEATH the factory paint.

y3scsU.jpg


Now I got a look at the side surfaces.

Really not what I expected. Paint wasn't coming off of the sides.

Yet.

0HvNaS.jpg


Probably wasn't wise to sand it by hand. Sure did produce a lot of brown dust.

oKahuY.jpg


Finally got it painted today, once the skies cleared. Won't use spray paint inside the building.

Should look a lot better now.

73
 
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The cabinet paint on these is famously poor. Got some static from Ebay tire-kickers about how nasty some of them looked. Yeah, I'm a geek. How it works is what impresses me. But how it looks has more influence on how it sells.

Decided to start painting the nastier specimens. Found some decent-quality Rust-Oleum that puts a texture on the finish. Seems to hide defects in the old paint surface.

But this one had a spot that just flaked off. The original finish just came away from a clean spot in the steel surface and took my new finish with it in that spot.

Bummer. Thought I'd be clever and just use paint stripper to remove the rest of the original "wrinkle" finish and paint the bare metal.

You could see some rust at one edge of the bare spot that had flaked away.

First application of the stripper looked promising.

17OTjk.jpg


Didn't remove as much as I expected, so I applied another layer of stripper. The first layer exposed a lot more rust than I would have expected to find UNDERNEATH the factory paint.

y3scsU.jpg


Now I got a look at the side surfaces.

Really not what I expected. Paint wasn't coming off of the sides.

Yet.

0HvNaS.jpg


Probably wasn't wise to sand it by hand. Sure did produce a lot of brown dust.

oKahuY.jpg


Finally got it painted today, once the skies cleared. Won't use spray paint inside the building.

Should look a lot better now.

73

Klean Strip Prep & Etch... basically a gallon of phosphoric acid for $15 at Home Depot or Lowes.

http://www.homedepot.com/p/Klean-Strip-1-gal-Phosphoric-Prep-and-Etch-GKPA30220/100406369
 
Way cool!

Makes me wonder how much the're asking for it.

They're out there. Lost track of how many we have converted since I started putting the digital display inside.

In the 90s, we would just strap a Galaxy FC-390 to the top of the cabinet. Got complaints about the frequency drifting. Didn't consider that the display would cause the thing to rat itself out if the frequency became unstable.

Finally got fairly good at fixing drift problems, but the solution would screw up the accuracy of the dial markings. Then my idiot light came on, and we started removing the white-plastic dial altogether. Makes a neater package with the digits behind the window.

The latest incarnation is sexier.

6HBpuS.jpg


But the smaller LCD display works just fine, too.

73
 
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Reactions: 2AF409
Good looking VFO,
Do you just sell the buffer amplifer units ?
Would be awesome if the buffer amplifier board was sold separately so it can be installed at the QTH.
 
We originally sold the buffer set up to install inside the Mark 3 SSB transmitter.

Like this: http://www.sliderfaq.com/OldNomadWebPages/SBinstall/index.htm

Eventually a customer suggested putting in inside the Siltronix. Won't fit inside a Glenn, though. My idiot light came on, and that's where most of them have been installed since then.

Never did actively market the thing. At 40 bucks, the support headaches made it a money loser. Too many of the people who bought it just couldn't get the right wire in the right hole.

Go figure.

Instructions to put it inside a Siltronix were posted at the CB Tricks forum, but it's been down for 7 months.

I'll see if I can find the file for that and post it here. Requires drilling two mount holes in the rear panel of the VFO. A paper template is included. Needs to be a 'mirror image' to be correct on the outside of the cabinet. Settled for telling the installer to face the ink side of the template against he rear panel. The assembled board includes new filter caps for the VFO. Kinda silly to operate it with the old ones.

I should probably include suggestions for reducing drift, but that wasn't part of the buffer-install routine at first.

I'll try to track down the install instructions.

73
 
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