Siltronix Mod 90-1 VFO pearce Simpson Simba

[Zman]

Whats the way to get my 90-1 to work with my Simba base?

 

[Zman]

bump

 

[AudioShockwav]

I have never had a Siltronics VFO, but I did run some of the PAL VFO`s Back in the day.
There were several different models and each one basically replaced one crystal in the radio and allowed you to put your radio on one channel and then use the VFO to move around across a large frequency range.

Different Models would output different frequency's to match what ever the mixer scheme was used in each radio.
Have a look at this page.
http://www.firestik.com/Instl-Art/vfo-sheet.gif
That shows the ones that were made by Firestick ( back then it was PAL), see how there are different models to fit different radios.
Now, I do not know if the Siltronics was made JUST for the Siltronics radio`s, if they made different models, or if you can swap a crystal inside the unit, and re-tune for a different output frequency.
Hopefully some one that is more familiar with that VFO that can asnwr these questions.

( on Edit You can go to that main page http://www.firestik.com/Tech_Docs/Pal_Menu.htm
Scroll down to the PAL VFO/VCO section and see how they were installed and some more info for reading)


73
Jeff

 

[Atlasta]

As I recall the Simba used a model 90-5 and not a 90-1. Not sure what the difference was between all the different models, but they all pretty much installed the same way. Remove the crystal that controls channel 23 (that would be the 11.250 MHz crystal on the Simba) and connect the VFO wires to this now-empty slot.

More information on Siltronix VFOs here: http://www.cbtricks.com/miscellaneous/vco/siltronix/model_90/graphics/siltronix_vfo_model_90_om.pdf

Oh one other thing: Never turn the VFO off even when you shut down the rest of the system. Silkie VFOs are famous for drifting and turning them on and off will only make it worse. Also watch out for ground loops, characterized by a 'warbling' sound in your transmit audio on sideband.

Expect to have to retune the receiver to accept the broader receive frequency range. Radios that have high 'Q' tend not to broadband very well and this causes receiver function to drop off on the higher frequencies.

Have fun with it!

 

[unit_399]

Atlasta is correct.You need to use a 90-5 vfo for the Simba. The 90.5 is centered around a 11.100 output freq. The 90-1 is centered at 11.955.

 

[Zman]

can i mod my VFO to work with the Simba? If not then ill just keep it for another radio and look for a -5....

 

[Zman]

I found a -5 on EBay that im watching like a hawk... I also won one that will go well with my Lafayette Comstat 25a! Im gonna hang onto my -1 if i ever get a radio that needs that particular VFO..

 

[ghutch]

vfo-simba

i had a simba with a model 90 vfo in the 70's worked great but i cannot remember if it was a 1 or 5....radio was on channel 23 if i remember. was able to get 18watts out and covered the world.
saw a new in the box simba on ebay about a year or so back....sure wanted to bid ...the thing brought 300-350 ??not bad considering the age and the new old stock condition. great receiver on the old one i had...good luck with the mods

 

[grimace]

can i mod my VFO to work with the Simba?

yes Siltronix VFO Model 90